Effects of Genotype, Seed Age and KNO3 on Germination of Radicchio (Cichorium intybus L.) and Endive (Cichorium endivia L.) Seed

After purchasing seed it often happens that all the seed is not used during one season, but they are stored for a couple of years. The aim of this study was to examine whether germination of radicchio and endive is still high enough after longer storage. We also wanted to define seed vigor in relation to the year of production and variety, and whether pretreatment with KNO3 could improve germination of older seed of radicchio and endive. The seed of three varieties of radicchio (‘Pallarossa’, ‘Verona’ and ‘Pandizucchero’) and three varieties of endive (‘Dječja glava’, ‘Pankalierka’ and ‘Escariol žuta’), from five seasons of certification (06/07, 07/08 08/09, 09/10 and 10/11) was tested. The following seed traits were analyzed: 1000 seed weight, moisture, germination rate, standard germination test, seed electrical conductivity, and the amount of absorbed water per gram of seed for 24 hours. Seed was germinated in two soaking treatments: in tap water with cooling pre-treatment, and KNO3. Based on the results, it was concluded that treatment with KNO3 significantly increases the standard germination of radicchio, as compared with water, and does not improve the germination of endive seed, but on the contrary, it has a negative effect. In both plant species, conductivity does not increase with seed age, because the oldest seed did not show the highest EC. In order to fully assess the impact of aging on seed vigor in tested plant species it is necessary to conduct further research

Monitoring of GM Soybean in High Categories of Seed on the Croatian Seed Market

Croatia has a long tradition in seed production for domestic use and for export. As an EU candidate country Croatia has harmonized its legislation with EU directives and therefore no GM soybean is authorized for cultivation. So far there is no record of introduction of GM soybean into Croatian environment; however there are earlier records of growing genetically modified soybean in the region. Aim of this study is to monitor current position in domestic seed market regarding genetically modified soybeans through substantial PCR screening for three lines: GTS 40-3-2 (Roundup Ready, RRS), A2704-12 (Liberty Link, LL) and MON89788 soybean (RR2). Screening was performed on high category soybean seed that was certified for Croatian market in season 2010/2011. Total of 18 different varieties of soybean seed were tested and all resulted negative for the presence of the tested GM lines. This is the first such screening of Croatian seed market

Usporedba u proizvodnji etanola iz kukuruza (Zea mays L.) između HTF hibrida i hibrida iz hrvatskih oplemenjivačkih programa

The aim of this study was to determine the differences in grain and ethanol yields between hybrids obtained from breeding programs in the Republic of Croatia and introduced HTF (High Total Fermentable) maize hybrids. The trial was conducted at three sites (Osijek, Beli Manastir and Zagreb) for two consecutive years (2012 and 2013) in three plant densities (60,000, 70,000 and 80,000 plants/ha). Pioneer HTF hybrids for the ethanol production were used as controls to assess the productivity of ethanol of hybrids from the Agricultural Institute Osijek and Bc Institute d.d. The study of ethanol production was carried out by using the Lemuz method. According to ANOVA statistical analysis, statistically significant differences in grain and ethanol yields were not found between HTF hybrids and hybrids of domestic breeding companies. Statistically significant difference was found in ethanol yield by sites (P<0.05) with highest average ethanol yield determined at Beli Manastir and the lowest in Osijek. Site × year × plant density interaction showed statistically significant difference in ethanol yield between hybrids and the most productive was the OS378 hybrid. Ethanol production of hybrids designated for this purpose did not produce higher ethanol yields than domestic hybrids from the same amount of grain.Cilj istraživanja bio je utvrditi razliku u proizvodnji zrna i etanola iz kukuruza između domaćih hibrida kukuruza koji se uobičajeno koriste za proizvodnju zrna i uvezenih HTF (High Total Fermentable) deklariranih hibrida za proizvodnju etanola. Poljski pokus je postavljen na 3 lokacije (Osijek, Beli Manastir, Zagreb) dvije godine uzastopno (2012, 2013) u tri gustoće sklopa (60,000, 70,000 i 80,000 biljaka/ha). Hibridi tvrtke Pioneer, deklarirani kao “HTF” hibridi za proizvodnju etanola iz zrna kukuruza korišteni su kao kontrola za procjenu produktivnosti etanola iz domaćih hibrida Poljoprivrednog instituta Osijek i Bc Instituta d.d. Laboratorijska proizvodnja etanola utvrđena je Lemuz metodom. Sukladno ANOVA statističkoj analizi nisu utvrđene statistički značajne razlike u prinosu zrna i etanola između HTF hibrida i hibrida domaćih oplemenjivačkih kuća. Statistički značajna razlika utvrđena je u prinosu etanola po lokalitetima (P<0.05) gdje je prosječno najveći prinos etanola ostvaren u Belom Manastiru, a najmanji u Osijeku. Interakcija lokalitet × godina × gustoća biljaka imala je statistički značajan utjecaj na prinos etanola između hibrida, a najproduktivniji je bio hibrid OS378. Deklarirani namjenski hibridi za proizvodnju etanola nisu proizveli više etanola u odnosu na domaće hibride iz iste količine zrna kukuruza

Effects of Genotype, Seed Age and KNO3 on Germination of Radicchio (Cichorium intybus L.) and Endive (Cichorium endivia L.) Seed

After purchasing seed it often happens that all the seed is not used during one season, but they are stored for a couple of years. The aim of this study was to examine whether germination of radicchio and endive is still high enough after longer storage. We also wanted to define seed vigor in relation to the year of production and variety, and whether pretreatment with KNO3 could improve germination of older seed of radicchio and endive. The seed of three varieties of radicchio (‘Pallarossa’, ‘Verona’ and ‘Pandizucchero’) and three varieties of endive (‘Dječja glava’, ‘Pankalierka’ and ‘Escariol žuta’), from five seasons of certification (06/07, 07/08 08/09, 09/10 and 10/11) was tested. The following seed traits were analyzed: 1000 seed weight, moisture, germination rate, standard germination test, seed electrical conductivity, and the amount of absorbed water per gram of seed for 24 hours. Seed was germinated in two soaking treatments: in tap water with cooling pre-treatment, and KNO3. Based on the results, it was concluded that treatment with KNO3 significantly increases the standard germination of radicchio, as compared with water, and does not improve the germination of endive seed, but on the contrary, it has a negative effect. In both plant species, conductivity does not increase with seed age, because the oldest seed did not show the highest EC. In order to fully assess the impact of aging on seed vigor in tested plant species it is necessary to conduct further research

Kemijske komponente kvalitete zrna sh2 genotipova kukuruza šećerca (Zea mays L. saccharata Sturt.) u ovisnosti o roku berbe

Kernel water (KW) and total soluble sugars (TSS) are major components of sweet corn taste, while total carotenoids (TC), total phenols (TP) and antioxidant activity (AA) contribute to its health benefits. Main objective was to determine the effect of genotype, harvest date and year on chemical components of kernel quality in shrunken (sh2) sweet corn. Nine sh2 genotypes were harvested at 3-day intervals from 20 to 32 days after pollination (DAP) over two years. Growing season significantly affected TC and TP only. Significant differences among genotypes were found for KW (75.3 - 77.4%), TTS (282.4 - 343.2 mg/g), TC (9.3 - 15.7 µg/g), TP (243.6 - 289.4 mg GEA/100 g) and AA (74.6 - 83.6 % inhibition). Effect of harvest date and genotype by harvest date interaction was significant for all traits. Compared to the 20 DAP, KW and TSS decreased, while TC, TP and AA tended to increase with later harvest dates. Based on KW, genotypes OS 5Esh and Overland extended harvest window up to 29 DAP. In contrast, optimum harvest window for genotype OS 244sh finished at 20 DAP. Extended harvest window for genotype Overland resulted in significant increase of TC (62.8%), TP (12.1%) and AA (12.4%).Voda u zrnu (KW) i ukupni topivi šećeri (TSS) su glavne komponente okusa kukuruza šećerca, dok ukupni karotenoidi (TC), ukupni fenoli (TP) i antioksidacijska aktivnost (AA) doprinose njegovim zdravstvenim benefitima. Glavni cilj bio je utvrditi utjecaj genotipa, rokova berbe i godine na kemijske komponenete kvalitete zrna shrunken (sh2) kukuruza šećerca. Devet sh2 genotipova brano je u trodnevnim intervalima od 20. do 32. dana nakon oplodnje (DAP) kroz dvije godine. Vegetacijska sezona značajno je utjecala samo na TC i TP. Utvrđene su značajne razlike između genotipova za KW (75.3 - 77.4%), TTS (282.4 - 343.2 mg/g), TC (9.3 - 15.7 µg/g), TP (243.6 - 289.4 mg GEA/100 g) i AA (74.6 - 83.6% inhibicije). Utjecaj roka berbe i interakcije genotipa s rokom berbe, bio je značajan za sva svojstva. U odnosu na 20. DAP, KW i TSS su se smanjili, dok su TC, TP i AA imali tendenciju porasta u kasnijim rokovima berbe. Na osnovu KW, genotipovi OS 5Esh i Overland su produžili rokove berbe do 29. DAP. Nasuprot tome, optimalni rok berbe za genotip OS 244sh završio je na 20. DAP. Produženi period berbe za genotip Overland rezultirao je značajnim povećanjem TC (62.8%), TP (12.1%) i AA (12.4%)

Chemical composition of su1 and sh2 hybrids of sweet corn at various stages of kernel development

U usporedbi s kukuruzom standardnog tipa, kemijski sastav zrna kukuruza šećerca karakterizira povećani sadržaj šećera i smanjeni sadržaj škroba. Dosadašnja istraživanja u svijetu pokazuju da kemijski sastav zrna kukuruza šećerca prvenstveno ovisi o tipu mutacije endosperma, dok u Hrvatskoj nije bilo ovakvih istraživanja. Stoga su glavni ciljevi ovog doktorskog rada bili istražiti promjene kemijskog sastava zrna tijekom dozrijevanja domaće germplazme kukuruza šećerca koja obuhvaća hibride tipa sugary (su1) i shrunken (sh2) mutacija kao i utjecaj okolinskih čimbenika (vegetacijske sezone i roka sjetve). Dva pokusa (1. i 2.) provedena su na pokusnom polju Poljoprivrednog instituta Osijek u Osijeku (PIO) uz primjenu standardnih agrotehničkih mjera za proizvodnju kukuruza šećerca. U pokusu 1., tijekom dvije vegetacijske sezone (2008. i 2009.) uzgojeno je devet hibrida kukuruza šećerca tipa sugary mutacije endosperma, a koji su kreirani na PIO. Sedam hibrida priznato je u Hrvatskoj (OS 250su, OS 254su, OS 253su, OS 255su, OS 256su, OS 247su, OS 258su) dok su dva hibrida eksperimentalni (Alpos su i OS 332su exp). U pokusu 2. tijekom vegetacijske sezone 2011., u tri roka sjetve posijano je pet sugary hibrida (OS 254su, OS 255su, OS 256su, OS 247su i OS 258su) izabranih na osnovu prethodnog dvogodišnjeg istraživanja, te pet shrunken hibrida i to Superslatki (Bc Institut za oplemenjivanje i proizvodnju bilja d.d.), jedan priznati (OS 244sh) i tri eksperimentalna (OS exp 1sh, OS exp 2sh, OS exp 3sh) hibrida PIO. Tijekom istraživanja na svim biljkama provedena je kontrolirana (ručna) oplodnja i uzeti uzorci za kemijske analize u pet stadija zrelosti zrna i to 17., 19., 21., 23. i 25. dan nakon oplodnje (DNO). Na uzorcima pokusa 1. utvrdio se sadržaj vode, saharoze, glukoze, fruktoze, ukupnih šećera, vodotopivih polisaharida, škroba, te parametri boje (L* i b*) u promatranim stadijima zrelosti zrna. Na uzorcima zrna iz pokusa 2. dodatno su utvrđeni ukupni fenoli i antioksidacijska aktivnost. U pokusu 1. optimalni stadij zrelosti zrna za berbu su1 hibrida nastupio je unutar istraživanog perioda zrelosti zrna, a hibridi su se međusobno razlikovali u dinamici otpuštanja vode tijekom dozrijevanja. Najdulji optimalni period za berbu obzirom na sadržaj vode u zrnu imao je hibrid OS 250su. Unutar optimalnih stadija zrelosti zrna za berbu, određene hibride poput OS 250su, OS 253su i OS 254su karakterizirao je i najveći sadržaj saharoze i ukupnih šećera. U pokusu 2. svi hibridi sh2 tipa mutacije imali su značajno viši sadržaj ukupnih šećera i značajno niži sadržaj vodotopivih polisaharida u zrnu u odnosu na su1 hibride. Kod su1 skupine mutanata najveći sadržaj ukupnih šećera utvrđen je za hibrid OS 256su, a kod sh2 skupine za hibrid OS 244sh. Najveći sadržaj ukupnih fenola unutar su1 skupine imao je hibrid OS 258su, a unutar sh2 skupine hibrid OS exp 2sh. Hibride sh2 mutacije karakterizirao je veći porast antioksidacijske aktivnosti u kasnijim stadijima zrelosti zrna u odnosu na su1 hibride. Vegetacijska sezona je značajno utjecala na većinu istraživanih svojstava su1 hibrida kukuruza šećerca. U usporedbi sa 2008., u toplijoj i sušnijoj 2009. vegetacijskoj sezoni utvrđen je značajno veći sadržaj pojedinačnih i ukupnih šećera te parametara boje (žutoća i intenzitet) zrna, dok je reakcija za sadržaj vode, vodotopivih polisaharida i škroba bila obrnuta. U pokusu 2. utvrđen je i značajan utjecaj roka sjetve na većinu kemijskih svojstava zrna istraživanih su1 i sh2 hibrida kukuruza šećerca. Rezultati višegodišnjih istraživanja jasno ukazuju da se hibridi domaće germplazme kukuruza šećerca međusobno značajno razlikuju po svim kemijskim svojstvima zrna tijekom dozrijevanja i da na specifičnu reakciju hibrida mogu utjecati i okolinski čimbenici (vegetacijska sezona i rok sjetve).Introduction: Sweet corn (Zea mays L. var. saccharata Sturt.) is an important vegetable crop. Although it is grown on much smaller areas than field corn, recently the production and consumption of sweet corn has been growing both in Europe and in the Republic of Croatia. The main reason for its popularity and growing consumers interest is conditioned by the pronounced trend of healthy human nutrition, and sweet corn is characterized by numerous highly nutritious properties. In comparison to field corn, sweet corn endosperm is characterized by an increased content of sugars and decreased content of starch. Previous studies are showing that the chemical content of kernels mostly depends on the type of endosperm mutation, but also on the genetic basis. In Croatia there is no comprehensive research in this area. Consequently, the main objective of this dissertation was to study domestic germplasm of sweet corn which includes hybrids of su1 (sugary-1) and sh2 (shrunken-2) types. Differences in chemical composition of kernels were assessed between and within groups of sugary and shrunken types of sweet corn hybrids based on three year field research. In trials with controlled pollination the content of water, sucrose, glucose, fructose, total sugars, water-soluble polysaccharides, starch, total phenols content in kernels, antioxidant activity and colour of kernels at various stages of kernel development were determined. In addition, the influence of environmental factors, year and sowing date, on kernel chemical composition of su1 and sh2 sweet corn hybrids during various stages of kernel development have been evaluated. Materials and methods: Field trials were on the experimental fields of the Agricultural Institute Osijek in Osijek (45°33'N, 18°41'E) during 2008, 2009 and 2011. During growing seasons, standard agricultural measures were applied. The first trial was set up over two years (2008 and 2009) and nine maize hybrids with sugary endosperm mutation (standard sugar) were sown. Hybrids in the trial are created at the Agricultural Institute Osijek. Seven hybrids are registered in the Republic of Croatia, and two hybrids are new, experimental hybrids, translated hybrids of the standard kernel type. Registered hybrids are OS 250su, OS 254su, OS 253su, OS 255su, OS 256su, OS 247su, OS 258su, and the two experimental hybrids are Alpos su and OS 332su. The trials were sown by hand, basic plot of each treatment was sown in two rows with a row spacing of 0.7 m and a length of 6.0 m. Controlled pollination was performed on all plants of the basic plot. It was ensured that sampling is done on certain days after pollination. Samples for chemical analysis of kernels were harvested five times during various stages of kernel development, on the 17th, 19th, 21st, 23rd and 25th day after pollination (DAP). Samples were harvested early in the morning, not later than 8 am and delivered to the laboratory at maximum of 10-15 min after harvest to avoid sugar loss. The content of water, sucrose, glucose, fructose, total sugars, water-soluble polysaccharides and starch were determined on a sample of five ears. Preparation of samples for chemical analysis began immediately upon reception of harvested ears. Kernels of sweet corn were separated from the cob by cutting with a sharp knife from the top to bottom of ear. A sample of 100 g of kernels was prepared, frozen, and frozen sample lyophilized. Lyophilization lasted for 48 h. Lyophilized samples were stored at -20 °C and used to determine starch content. The rest of the separated kernels were crushed and homogenized using a stick mixer, blender. Homogenized sample was used to determine content of water, sugar and water-soluble polysaccharides. Determination of water content was carried out by drying of homogenized sample weighing 5 g in an oven at 105 °C to constant weight. Sugars and water-soluble polysaccharides extractions were conducted with ultrapure water according to a modified method (Sturm et al., 2003). Determination of sugars and water-soluble polysaccharides was performed on a high-performance liquid chromatographic system (HPLC) series 200. The standard solution consisted of sucrose, glucose, galactose (internal standard) and fructose. Sugars from the water extract were identified by their retention times and quantified by the peak area by the method of internal standard. Total sugars are expressed as the sum of sucrose, glucose and fructose. Other peaks on the chromatograph were used to calculate water-soluble polysaccharides. The content of sugars and water-soluble polysaccharides is expressed in % in dry matter. The starch content was determined in a lyophilized sample by the polarimetric method according to Ewers (1997). The parameters of colour (L* and b*) in the ground samples were determined according to the CIELAB method (CIE, 1976) with a three-filter colorimeter Chroma meter Konica Minolta CR-400. Colours are described through three components. L* (luminance) represents the colour intensity (brightness) and the coordinates a* and b* colours. In this study, values of the L* and b* (ratio of yellow and blue colour) components were monitored. Second trial was set up in 2011. Five sugary hybrids (selected on the basis of a previous two-year study) and five shrunken hybrids (supersweet sweet corn) were sown in three sowing dates. Selected sugary hybrids were selected based on the results of chemical analyses but also on the base of real needs of producers and the possibility of commercialization of selected hybrids. Selected sugary hybrids were OS 254su, OS 255su, OS 256su, OS 247su and OS 258su. Shrunken hybrids represented in the trial were one registered hybrid of Agricultural Institute Osijek (OS 244sh), one registered hybrid of Bc Institute Zagreb (SUPERSLATKI) and three experimental hybrids of Agricultural Institute Osijek (OS exp 1sh, OS exp 2sh, OS exp 3sh). The first sowing date was 14th April and this sowing date reflects the optimal sowing date in most years in the area where the trial was conducted. The second sowing period was two weeks after the first sowing period and two weeks before the third sowing period. These sowing dates were selected as the optimal sowing days to be applied in production of sweet corn with a distance between sowing dates sufficient to ensure successive harvesting and chemical analysis in the laboratory. Second trial was sown as Trial 1 and controlled pollination was performed on all plants of the basic plot as in Trial 1. Samples for chemical analysis of kernels were harvested five times during various stages of kernel development. Beside the parameters analysed in Trial 1, the chemical analysis of the kernel included the analyses of total phenols and the antioxidant activity. As in Trial 1 after receiving the samples, colour of kernels was determined on the ear and sample was prepared for chemical analysis. Sample of 100 g of kernels was frozen and lyophilized. Lyophilized samples were stored at -20 °C and used for determination of starch, total phenols and antioxidant activity. The content of total phenols in kernel of sweet corn was determined spectrophotometrically by modified semimicro method according to Singleton and Rossi (1965). The concentration of total phenols was calculated from a standard curve with gallic acid as standard and expressed as gallic acid equivalent in dry matter (mg GAE/100 g DW). Total antioxidant activity was determined spectrophotometrically by DPPH method according to Brand-Williams et al. (1995) and expressed as gallic acid equivalent in dry matter (mg GAE/100 g DW). The GENSTAT 7.2 program was used to process the results. Results and conclusions: The results of this research show that relatively small changes in the water content in the kernel during the observed stages of kernel development are associated with significant changes in the chemical composition of kernel. The decrease in water content in kernel during maturation is significantly associated with a decrease in the content of single and total sugars (from r=0.61 to r=0.72) as well as a decrease in the content of total phenols (r= 0.50). The decrease in kernel water content during kernel development is significantly associated with an increase in water soluble polysaccharides (r=-0.70), starch (r=-0.76), antioxidant activity (r=-0.43) and kernel colour (r=-0.39). During the observed maturation period, the metabolic processes in the kernel are very intensive, so the harvesting of sweet corn in the appropriate stage of kernel development is crucial to ensure high nutritional quality. For all observed characteristics, significant differences were found between the tested hybrids, where the type of endosperm mutation is the most important factor for the content of sucrose, total sugars, water soluble polysaccharides and starch in kernel. The change in water content, single and total sugars, water-soluble polysaccharides and starch during kernel development is greater in su1 hybrids compared to sh2 hybrids. Greater increase in antioxidant activity during maturation was found for sh2 hybrids compared to su1 hybrids. Significant differences were found between hybrids of the same type of mutation in content and dynamics of change of content during kernel development for all observed characteristics. Considering the duration of the optimal harvest period, sugar content and reduction of sugar content by kernel development, and the lowest starch content hybrids OS 254su and OS 256su can be distinguished as the best in the group of su1 hybrids, The new sh2 hybrid OS exp 2sh had a slightly lower initial content of total sugars compared to the standard hybrid OS 244sh, while in the hybrid OS exp 2sh the content of total sugars did not change significantly during the optimal harvest period and had a significantly higher sugar content at the last stage of maturity compared to other sh2 hybrids. For the OS exp 2sh hybrid, very little variation was found between different sowing dates both in the content of total sugars and in the change of total sugars during maturation, which is very important considering that the selection of a hybrid for commercial production depends on the stability of its performance through environments. The results of this research for total phenol content and antioxidant activity show a high part of genotype × maturity stage x sowing date interaction in total variability. Although significant differences were found between the examined hybrids for both characteristics, the dynamics of change during kernel development as well as the variation between sowing dates prevent the emphasis of hybrid with potentially higher functional value. In any case, the identified differences between genotypes indicate that research needs to be continued in a way to include more genotypes and involve more groups of bioactive compounds (especially carotenoids) in order to isolate hybrids with potentially higher health benefits

Chemical composition of su1 and sh2 hybrids of sweet corn at various stages of kernel development

U usporedbi s kukuruzom standardnog tipa, kemijski sastav zrna kukuruza šećerca karakterizira povećani sadržaj šećera i smanjeni sadržaj škroba. Dosadašnja istraživanja u svijetu pokazuju da kemijski sastav zrna kukuruza šećerca prvenstveno ovisi o tipu mutacije endosperma, dok u Hrvatskoj nije bilo ovakvih istraživanja. Stoga su glavni ciljevi ovog doktorskog rada bili istražiti promjene kemijskog sastava zrna tijekom dozrijevanja domaće germplazme kukuruza šećerca koja obuhvaća hibride tipa sugary (su1) i shrunken (sh2) mutacija kao i utjecaj okolinskih čimbenika (vegetacijske sezone i roka sjetve). Dva pokusa (1. i 2.) provedena su na pokusnom polju Poljoprivrednog instituta Osijek u Osijeku (PIO) uz primjenu standardnih agrotehničkih mjera za proizvodnju kukuruza šećerca. U pokusu 1., tijekom dvije vegetacijske sezone (2008. i 2009.) uzgojeno je devet hibrida kukuruza šećerca tipa sugary mutacije endosperma, a koji su kreirani na PIO. Sedam hibrida priznato je u Hrvatskoj (OS 250su, OS 254su, OS 253su, OS 255su, OS 256su, OS 247su, OS 258su) dok su dva hibrida eksperimentalni (Alpos su i OS 332su exp). U pokusu 2. tijekom vegetacijske sezone 2011., u tri roka sjetve posijano je pet sugary hibrida (OS 254su, OS 255su, OS 256su, OS 247su i OS 258su) izabranih na osnovu prethodnog dvogodišnjeg istraživanja, te pet shrunken hibrida i to Superslatki (Bc Institut za oplemenjivanje i proizvodnju bilja d.d.), jedan priznati (OS 244sh) i tri eksperimentalna (OS exp 1sh, OS exp 2sh, OS exp 3sh) hibrida PIO. Tijekom istraživanja na svim biljkama provedena je kontrolirana (ručna) oplodnja i uzeti uzorci za kemijske analize u pet stadija zrelosti zrna i to 17., 19., 21., 23. i 25. dan nakon oplodnje (DNO). Na uzorcima pokusa 1. utvrdio se sadržaj vode, saharoze, glukoze, fruktoze, ukupnih šećera, vodotopivih polisaharida, škroba, te parametri boje (L* i b*) u promatranim stadijima zrelosti zrna. Na uzorcima zrna iz pokusa 2. dodatno su utvrđeni ukupni fenoli i antioksidacijska aktivnost. U pokusu 1. optimalni stadij zrelosti zrna za berbu su1 hibrida nastupio je unutar istraživanog perioda zrelosti zrna, a hibridi su se međusobno razlikovali u dinamici otpuštanja vode tijekom dozrijevanja. Najdulji optimalni period za berbu obzirom na sadržaj vode u zrnu imao je hibrid OS 250su. Unutar optimalnih stadija zrelosti zrna za berbu, određene hibride poput OS 250su, OS 253su i OS 254su karakterizirao je i najveći sadržaj saharoze i ukupnih šećera. U pokusu 2. svi hibridi sh2 tipa mutacije imali su značajno viši sadržaj ukupnih šećera i značajno niži sadržaj vodotopivih polisaharida u zrnu u odnosu na su1 hibride. Kod su1 skupine mutanata najveći sadržaj ukupnih šećera utvrđen je za hibrid OS 256su, a kod sh2 skupine za hibrid OS 244sh. Najveći sadržaj ukupnih fenola unutar su1 skupine imao je hibrid OS 258su, a unutar sh2 skupine hibrid OS exp 2sh. Hibride sh2 mutacije karakterizirao je veći porast antioksidacijske aktivnosti u kasnijim stadijima zrelosti zrna u odnosu na su1 hibride. Vegetacijska sezona je značajno utjecala na većinu istraživanih svojstava su1 hibrida kukuruza šećerca. U usporedbi sa 2008., u toplijoj i sušnijoj 2009. vegetacijskoj sezoni utvrđen je značajno veći sadržaj pojedinačnih i ukupnih šećera te parametara boje (žutoća i intenzitet) zrna, dok je reakcija za sadržaj vode, vodotopivih polisaharida i škroba bila obrnuta. U pokusu 2. utvrđen je i značajan utjecaj roka sjetve na većinu kemijskih svojstava zrna istraživanih su1 i sh2 hibrida kukuruza šećerca. Rezultati višegodišnjih istraživanja jasno ukazuju da se hibridi domaće germplazme kukuruza šećerca međusobno značajno razlikuju po svim kemijskim svojstvima zrna tijekom dozrijevanja i da na specifičnu reakciju hibrida mogu utjecati i okolinski čimbenici (vegetacijska sezona i rok sjetve).Introduction: Sweet corn (Zea mays L. var. saccharata Sturt.) is an important vegetable crop. Although it is grown on much smaller areas than field corn, recently the production and consumption of sweet corn has been growing both in Europe and in the Republic of Croatia. The main reason for its popularity and growing consumers interest is conditioned by the pronounced trend of healthy human nutrition, and sweet corn is characterized by numerous highly nutritious properties. In comparison to field corn, sweet corn endosperm is characterized by an increased content of sugars and decreased content of starch. Previous studies are showing that the chemical content of kernels mostly depends on the type of endosperm mutation, but also on the genetic basis. In Croatia there is no comprehensive research in this area. Consequently, the main objective of this dissertation was to study domestic germplasm of sweet corn which includes hybrids of su1 (sugary-1) and sh2 (shrunken-2) types. Differences in chemical composition of kernels were assessed between and within groups of sugary and shrunken types of sweet corn hybrids based on three year field research. In trials with controlled pollination the content of water, sucrose, glucose, fructose, total sugars, water-soluble polysaccharides, starch, total phenols content in kernels, antioxidant activity and colour of kernels at various stages of kernel development were determined. In addition, the influence of environmental factors, year and sowing date, on kernel chemical composition of su1 and sh2 sweet corn hybrids during various stages of kernel development have been evaluated. Materials and methods: Field trials were on the experimental fields of the Agricultural Institute Osijek in Osijek (45°33'N, 18°41'E) during 2008, 2009 and 2011. During growing seasons, standard agricultural measures were applied. The first trial was set up over two years (2008 and 2009) and nine maize hybrids with sugary endosperm mutation (standard sugar) were sown. Hybrids in the trial are created at the Agricultural Institute Osijek. Seven hybrids are registered in the Republic of Croatia, and two hybrids are new, experimental hybrids, translated hybrids of the standard kernel type. Registered hybrids are OS 250su, OS 254su, OS 253su, OS 255su, OS 256su, OS 247su, OS 258su, and the two experimental hybrids are Alpos su and OS 332su. The trials were sown by hand, basic plot of each treatment was sown in two rows with a row spacing of 0.7 m and a length of 6.0 m. Controlled pollination was performed on all plants of the basic plot. It was ensured that sampling is done on certain days after pollination. Samples for chemical analysis of kernels were harvested five times during various stages of kernel development, on the 17th, 19th, 21st, 23rd and 25th day after pollination (DAP). Samples were harvested early in the morning, not later than 8 am and delivered to the laboratory at maximum of 10-15 min after harvest to avoid sugar loss. The content of water, sucrose, glucose, fructose, total sugars, water-soluble polysaccharides and starch were determined on a sample of five ears. Preparation of samples for chemical analysis began immediately upon reception of harvested ears. Kernels of sweet corn were separated from the cob by cutting with a sharp knife from the top to bottom of ear. A sample of 100 g of kernels was prepared, frozen, and frozen sample lyophilized. Lyophilization lasted for 48 h. Lyophilized samples were stored at -20 °C and used to determine starch content. The rest of the separated kernels were crushed and homogenized using a stick mixer, blender. Homogenized sample was used to determine content of water, sugar and water-soluble polysaccharides. Determination of water content was carried out by drying of homogenized sample weighing 5 g in an oven at 105 °C to constant weight. Sugars and water-soluble polysaccharides extractions were conducted with ultrapure water according to a modified method (Sturm et al., 2003). Determination of sugars and water-soluble polysaccharides was performed on a high-performance liquid chromatographic system (HPLC) series 200. The standard solution consisted of sucrose, glucose, galactose (internal standard) and fructose. Sugars from the water extract were identified by their retention times and quantified by the peak area by the method of internal standard. Total sugars are expressed as the sum of sucrose, glucose and fructose. Other peaks on the chromatograph were used to calculate water-soluble polysaccharides. The content of sugars and water-soluble polysaccharides is expressed in % in dry matter. The starch content was determined in a lyophilized sample by the polarimetric method according to Ewers (1997). The parameters of colour (L* and b*) in the ground samples were determined according to the CIELAB method (CIE, 1976) with a three-filter colorimeter Chroma meter Konica Minolta CR-400. Colours are described through three components. L* (luminance) represents the colour intensity (brightness) and the coordinates a* and b* colours. In this study, values of the L* and b* (ratio of yellow and blue colour) components were monitored. Second trial was set up in 2011. Five sugary hybrids (selected on the basis of a previous two-year study) and five shrunken hybrids (supersweet sweet corn) were sown in three sowing dates. Selected sugary hybrids were selected based on the results of chemical analyses but also on the base of real needs of producers and the possibility of commercialization of selected hybrids. Selected sugary hybrids were OS 254su, OS 255su, OS 256su, OS 247su and OS 258su. Shrunken hybrids represented in the trial were one registered hybrid of Agricultural Institute Osijek (OS 244sh), one registered hybrid of Bc Institute Zagreb (SUPERSLATKI) and three experimental hybrids of Agricultural Institute Osijek (OS exp 1sh, OS exp 2sh, OS exp 3sh). The first sowing date was 14th April and this sowing date reflects the optimal sowing date in most years in the area where the trial was conducted. The second sowing period was two weeks after the first sowing period and two weeks before the third sowing period. These sowing dates were selected as the optimal sowing days to be applied in production of sweet corn with a distance between sowing dates sufficient to ensure successive harvesting and chemical analysis in the laboratory. Second trial was sown as Trial 1 and controlled pollination was performed on all plants of the basic plot as in Trial 1. Samples for chemical analysis of kernels were harvested five times during various stages of kernel development. Beside the parameters analysed in Trial 1, the chemical analysis of the kernel included the analyses of total phenols and the antioxidant activity. As in Trial 1 after receiving the samples, colour of kernels was determined on the ear and sample was prepared for chemical analysis. Sample of 100 g of kernels was frozen and lyophilized. Lyophilized samples were stored at -20 °C and used for determination of starch, total phenols and antioxidant activity. The content of total phenols in kernel of sweet corn was determined spectrophotometrically by modified semimicro method according to Singleton and Rossi (1965). The concentration of total phenols was calculated from a standard curve with gallic acid as standard and expressed as gallic acid equivalent in dry matter (mg GAE/100 g DW). Total antioxidant activity was determined spectrophotometrically by DPPH method according to Brand-Williams et al. (1995) and expressed as gallic acid equivalent in dry matter (mg GAE/100 g DW). The GENSTAT 7.2 program was used to process the results. Results and conclusions: The results of this research show that relatively small changes in the water content in the kernel during the observed stages of kernel development are associated with significant changes in the chemical composition of kernel. The decrease in water content in kernel during maturation is significantly associated with a decrease in the content of single and total sugars (from r=0.61 to r=0.72) as well as a decrease in the content of total phenols (r= 0.50). The decrease in kernel water content during kernel development is significantly associated with an increase in water soluble polysaccharides (r=-0.70), starch (r=-0.76), antioxidant activity (r=-0.43) and kernel colour (r=-0.39). During the observed maturation period, the metabolic processes in the kernel are very intensive, so the harvesting of sweet corn in the appropriate stage of kernel development is crucial to ensure high nutritional quality. For all observed characteristics, significant differences were found between the tested hybrids, where the type of endosperm mutation is the most important factor for the content of sucrose, total sugars, water soluble polysaccharides and starch in kernel. The change in water content, single and total sugars, water-soluble polysaccharides and starch during kernel development is greater in su1 hybrids compared to sh2 hybrids. Greater increase in antioxidant activity during maturation was found for sh2 hybrids compared to su1 hybrids. Significant differences were found between hybrids of the same type of mutation in content and dynamics of change of content during kernel development for all observed characteristics. Considering the duration of the optimal harvest period, sugar content and reduction of sugar content by kernel development, and the lowest starch content hybrids OS 254su and OS 256su can be distinguished as the best in the group of su1 hybrids, The new sh2 hybrid OS exp 2sh had a slightly lower initial content of total sugars compared to the standard hybrid OS 244sh, while in the hybrid OS exp 2sh the content of total sugars did not change significantly during the optimal harvest period and had a significantly higher sugar content at the last stage of maturity compared to other sh2 hybrids. For the OS exp 2sh hybrid, very little variation was found between different sowing dates both in the content of total sugars and in the change of total sugars during maturation, which is very important considering that the selection of a hybrid for commercial production depends on the stability of its performance through environments. The results of this research for total phenol content and antioxidant activity show a high part of genotype × maturity stage x sowing date interaction in total variability. Although significant differences were found between the examined hybrids for both characteristics, the dynamics of change during kernel development as well as the variation between sowing dates prevent the emphasis of hybrid with potentially higher functional value. In any case, the identified differences between genotypes indicate that research needs to be continued in a way to include more genotypes and involve more groups of bioactive compounds (especially carotenoids) in order to isolate hybrids with potentially higher health benefits

Chemical composition of su1 and sh2 hybrids of sweet corn at various stages of kernel development

U usporedbi s kukuruzom standardnog tipa, kemijski sastav zrna kukuruza šećerca karakterizira povećani sadržaj šećera i smanjeni sadržaj škroba. Dosadašnja istraživanja u svijetu pokazuju da kemijski sastav zrna kukuruza šećerca prvenstveno ovisi o tipu mutacije endosperma, dok u Hrvatskoj nije bilo ovakvih istraživanja. Stoga su glavni ciljevi ovog doktorskog rada bili istražiti promjene kemijskog sastava zrna tijekom dozrijevanja domaće germplazme kukuruza šećerca koja obuhvaća hibride tipa sugary (su1) i shrunken (sh2) mutacija kao i utjecaj okolinskih čimbenika (vegetacijske sezone i roka sjetve). Dva pokusa (1. i 2.) provedena su na pokusnom polju Poljoprivrednog instituta Osijek u Osijeku (PIO) uz primjenu standardnih agrotehničkih mjera za proizvodnju kukuruza šećerca. U pokusu 1., tijekom dvije vegetacijske sezone (2008. i 2009.) uzgojeno je devet hibrida kukuruza šećerca tipa sugary mutacije endosperma, a koji su kreirani na PIO. Sedam hibrida priznato je u Hrvatskoj (OS 250su, OS 254su, OS 253su, OS 255su, OS 256su, OS 247su, OS 258su) dok su dva hibrida eksperimentalni (Alpos su i OS 332su exp). U pokusu 2. tijekom vegetacijske sezone 2011., u tri roka sjetve posijano je pet sugary hibrida (OS 254su, OS 255su, OS 256su, OS 247su i OS 258su) izabranih na osnovu prethodnog dvogodišnjeg istraživanja, te pet shrunken hibrida i to Superslatki (Bc Institut za oplemenjivanje i proizvodnju bilja d.d.), jedan priznati (OS 244sh) i tri eksperimentalna (OS exp 1sh, OS exp 2sh, OS exp 3sh) hibrida PIO. Tijekom istraživanja na svim biljkama provedena je kontrolirana (ručna) oplodnja i uzeti uzorci za kemijske analize u pet stadija zrelosti zrna i to 17., 19., 21., 23. i 25. dan nakon oplodnje (DNO). Na uzorcima pokusa 1. utvrdio se sadržaj vode, saharoze, glukoze, fruktoze, ukupnih šećera, vodotopivih polisaharida, škroba, te parametri boje (L* i b*) u promatranim stadijima zrelosti zrna. Na uzorcima zrna iz pokusa 2. dodatno su utvrđeni ukupni fenoli i antioksidacijska aktivnost. U pokusu 1. optimalni stadij zrelosti zrna za berbu su1 hibrida nastupio je unutar istraživanog perioda zrelosti zrna, a hibridi su se međusobno razlikovali u dinamici otpuštanja vode tijekom dozrijevanja. Najdulji optimalni period za berbu obzirom na sadržaj vode u zrnu imao je hibrid OS 250su. Unutar optimalnih stadija zrelosti zrna za berbu, određene hibride poput OS 250su, OS 253su i OS 254su karakterizirao je i najveći sadržaj saharoze i ukupnih šećera. U pokusu 2. svi hibridi sh2 tipa mutacije imali su značajno viši sadržaj ukupnih šećera i značajno niži sadržaj vodotopivih polisaharida u zrnu u odnosu na su1 hibride. Kod su1 skupine mutanata najveći sadržaj ukupnih šećera utvrđen je za hibrid OS 256su, a kod sh2 skupine za hibrid OS 244sh. Najveći sadržaj ukupnih fenola unutar su1 skupine imao je hibrid OS 258su, a unutar sh2 skupine hibrid OS exp 2sh. Hibride sh2 mutacije karakterizirao je veći porast antioksidacijske aktivnosti u kasnijim stadijima zrelosti zrna u odnosu na su1 hibride. Vegetacijska sezona je značajno utjecala na većinu istraživanih svojstava su1 hibrida kukuruza šećerca. U usporedbi sa 2008., u toplijoj i sušnijoj 2009. vegetacijskoj sezoni utvrđen je značajno veći sadržaj pojedinačnih i ukupnih šećera te parametara boje (žutoća i intenzitet) zrna, dok je reakcija za sadržaj vode, vodotopivih polisaharida i škroba bila obrnuta. U pokusu 2. utvrđen je i značajan utjecaj roka sjetve na većinu kemijskih svojstava zrna istraživanih su1 i sh2 hibrida kukuruza šećerca. Rezultati višegodišnjih istraživanja jasno ukazuju da se hibridi domaće germplazme kukuruza šećerca međusobno značajno razlikuju po svim kemijskim svojstvima zrna tijekom dozrijevanja i da na specifičnu reakciju hibrida mogu utjecati i okolinski čimbenici (vegetacijska sezona i rok sjetve).Introduction: Sweet corn (Zea mays L. var. saccharata Sturt.) is an important vegetable crop. Although it is grown on much smaller areas than field corn, recently the production and consumption of sweet corn has been growing both in Europe and in the Republic of Croatia. The main reason for its popularity and growing consumers interest is conditioned by the pronounced trend of healthy human nutrition, and sweet corn is characterized by numerous highly nutritious properties. In comparison to field corn, sweet corn endosperm is characterized by an increased content of sugars and decreased content of starch. Previous studies are showing that the chemical content of kernels mostly depends on the type of endosperm mutation, but also on the genetic basis. In Croatia there is no comprehensive research in this area. Consequently, the main objective of this dissertation was to study domestic germplasm of sweet corn which includes hybrids of su1 (sugary-1) and sh2 (shrunken-2) types. Differences in chemical composition of kernels were assessed between and within groups of sugary and shrunken types of sweet corn hybrids based on three year field research. In trials with controlled pollination the content of water, sucrose, glucose, fructose, total sugars, water-soluble polysaccharides, starch, total phenols content in kernels, antioxidant activity and colour of kernels at various stages of kernel development were determined. In addition, the influence of environmental factors, year and sowing date, on kernel chemical composition of su1 and sh2 sweet corn hybrids during various stages of kernel development have been evaluated. Materials and methods: Field trials were on the experimental fields of the Agricultural Institute Osijek in Osijek (45°33'N, 18°41'E) during 2008, 2009 and 2011. During growing seasons, standard agricultural measures were applied. The first trial was set up over two years (2008 and 2009) and nine maize hybrids with sugary endosperm mutation (standard sugar) were sown. Hybrids in the trial are created at the Agricultural Institute Osijek. Seven hybrids are registered in the Republic of Croatia, and two hybrids are new, experimental hybrids, translated hybrids of the standard kernel type. Registered hybrids are OS 250su, OS 254su, OS 253su, OS 255su, OS 256su, OS 247su, OS 258su, and the two experimental hybrids are Alpos su and OS 332su. The trials were sown by hand, basic plot of each treatment was sown in two rows with a row spacing of 0.7 m and a length of 6.0 m. Controlled pollination was performed on all plants of the basic plot. It was ensured that sampling is done on certain days after pollination. Samples for chemical analysis of kernels were harvested five times during various stages of kernel development, on the 17th, 19th, 21st, 23rd and 25th day after pollination (DAP). Samples were harvested early in the morning, not later than 8 am and delivered to the laboratory at maximum of 10-15 min after harvest to avoid sugar loss. The content of water, sucrose, glucose, fructose, total sugars, water-soluble polysaccharides and starch were determined on a sample of five ears. Preparation of samples for chemical analysis began immediately upon reception of harvested ears. Kernels of sweet corn were separated from the cob by cutting with a sharp knife from the top to bottom of ear. A sample of 100 g of kernels was prepared, frozen, and frozen sample lyophilized. Lyophilization lasted for 48 h. Lyophilized samples were stored at -20 °C and used to determine starch content. The rest of the separated kernels were crushed and homogenized using a stick mixer, blender. Homogenized sample was used to determine content of water, sugar and water-soluble polysaccharides. Determination of water content was carried out by drying of homogenized sample weighing 5 g in an oven at 105 °C to constant weight. Sugars and water-soluble polysaccharides extractions were conducted with ultrapure water according to a modified method (Sturm et al., 2003). Determination of sugars and water-soluble polysaccharides was performed on a high-performance liquid chromatographic system (HPLC) series 200. The standard solution consisted of sucrose, glucose, galactose (internal standard) and fructose. Sugars from the water extract were identified by their retention times and quantified by the peak area by the method of internal standard. Total sugars are expressed as the sum of sucrose, glucose and fructose. Other peaks on the chromatograph were used to calculate water-soluble polysaccharides. The content of sugars and water-soluble polysaccharides is expressed in % in dry matter. The starch content was determined in a lyophilized sample by the polarimetric method according to Ewers (1997). The parameters of colour (L* and b*) in the ground samples were determined according to the CIELAB method (CIE, 1976) with a three-filter colorimeter Chroma meter Konica Minolta CR-400. Colours are described through three components. L* (luminance) represents the colour intensity (brightness) and the coordinates a* and b* colours. In this study, values of the L* and b* (ratio of yellow and blue colour) components were monitored. Second trial was set up in 2011. Five sugary hybrids (selected on the basis of a previous two-year study) and five shrunken hybrids (supersweet sweet corn) were sown in three sowing dates. Selected sugary hybrids were selected based on the results of chemical analyses but also on the base of real needs of producers and the possibility of commercialization of selected hybrids. Selected sugary hybrids were OS 254su, OS 255su, OS 256su, OS 247su and OS 258su. Shrunken hybrids represented in the trial were one registered hybrid of Agricultural Institute Osijek (OS 244sh), one registered hybrid of Bc Institute Zagreb (SUPERSLATKI) and three experimental hybrids of Agricultural Institute Osijek (OS exp 1sh, OS exp 2sh, OS exp 3sh). The first sowing date was 14th April and this sowing date reflects the optimal sowing date in most years in the area where the trial was conducted. The second sowing period was two weeks after the first sowing period and two weeks before the third sowing period. These sowing dates were selected as the optimal sowing days to be applied in production of sweet corn with a distance between sowing dates sufficient to ensure successive harvesting and chemical analysis in the laboratory. Second trial was sown as Trial 1 and controlled pollination was performed on all plants of the basic plot as in Trial 1. Samples for chemical analysis of kernels were harvested five times during various stages of kernel development. Beside the parameters analysed in Trial 1, the chemical analysis of the kernel included the analyses of total phenols and the antioxidant activity. As in Trial 1 after receiving the samples, colour of kernels was determined on the ear and sample was prepared for chemical analysis. Sample of 100 g of kernels was frozen and lyophilized. Lyophilized samples were stored at -20 °C and used for determination of starch, total phenols and antioxidant activity. The content of total phenols in kernel of sweet corn was determined spectrophotometrically by modified semimicro method according to Singleton and Rossi (1965). The concentration of total phenols was calculated from a standard curve with gallic acid as standard and expressed as gallic acid equivalent in dry matter (mg GAE/100 g DW). Total antioxidant activity was determined spectrophotometrically by DPPH method according to Brand-Williams et al. (1995) and expressed as gallic acid equivalent in dry matter (mg GAE/100 g DW). The GENSTAT 7.2 program was used to process the results. Results and conclusions: The results of this research show that relatively small changes in the water content in the kernel during the observed stages of kernel development are associated with significant changes in the chemical composition of kernel. The decrease in water content in kernel during maturation is significantly associated with a decrease in the content of single and total sugars (from r=0.61 to r=0.72) as well as a decrease in the content of total phenols (r= 0.50). The decrease in kernel water content during kernel development is significantly associated with an increase in water soluble polysaccharides (r=-0.70), starch (r=-0.76), antioxidant activity (r=-0.43) and kernel colour (r=-0.39). During the observed maturation period, the metabolic processes in the kernel are very intensive, so the harvesting of sweet corn in the appropriate stage of kernel development is crucial to ensure high nutritional quality. For all observed characteristics, significant differences were found between the tested hybrids, where the type of endosperm mutation is the most important factor for the content of sucrose, total sugars, water soluble polysaccharides and starch in kernel. The change in water content, single and total sugars, water-soluble polysaccharides and starch during kernel development is greater in su1 hybrids compared to sh2 hybrids. Greater increase in antioxidant activity during maturation was found for sh2 hybrids compared to su1 hybrids. Significant differences were found between hybrids of the same type of mutation in content and dynamics of change of content during kernel development for all observed characteristics. Considering the duration of the optimal harvest period, sugar content and reduction of sugar content by kernel development, and the lowest starch content hybrids OS 254su and OS 256su can be distinguished as the best in the group of su1 hybrids, The new sh2 hybrid OS exp 2sh had a slightly lower initial content of total sugars compared to the standard hybrid OS 244sh, while in the hybrid OS exp 2sh the content of total sugars did not change significantly during the optimal harvest period and had a significantly higher sugar content at the last stage of maturity compared to other sh2 hybrids. For the OS exp 2sh hybrid, very little variation was found between different sowing dates both in the content of total sugars and in the change of total sugars during maturation, which is very important considering that the selection of a hybrid for commercial production depends on the stability of its performance through environments. The results of this research for total phenol content and antioxidant activity show a high part of genotype × maturity stage x sowing date interaction in total variability. Although significant differences were found between the examined hybrids for both characteristics, the dynamics of change during kernel development as well as the variation between sowing dates prevent the emphasis of hybrid with potentially higher functional value. In any case, the identified differences between genotypes indicate that research needs to be continued in a way to include more genotypes and involve more groups of bioactive compounds (especially carotenoids) in order to isolate hybrids with potentially higher health benefits

Monitoring of GM Soybean in High Categories of Seed on the Croatian Seed Market

Croatia has a long tradition in seed production for domestic use and for export. As an EU candidate country Croatia has harmonized its legislation with EU directives and therefore no GM soybean is authorized for cultivation. So far there is no record of introduction of GM soybean into Croatian environment; however there are earlier records of growing genetically modified soybean in the region. Aim of this study is to monitor current position in domestic seed market regarding genetically modified soybeans through substantial PCR screening for three lines: GTS 40-3-2 (Roundup Ready, RRS), A2704-12 (Liberty Link, LL) and MON89788 soybean (RR2). Screening was performed on high category soybean seed that was certified for Croatian market in season 2010/2011. Total of 18 different varieties of soybean seed were tested and all resulted negative for the presence of the tested GM lines. This is the first such screening of Croatian seed market

Effect of Harvest Date on Kernel Quality and Antioxidant Activity in <i>su1</i> Sweet Corn Genotypes

In order to achieve a high-quality product, sweet corn should be harvested at the optimal stage of maturity. The taste of sweet corn depends largely on the kernel moisture (KM) and total sugars (TS) content while its health properties are attributed to the content of total phenols (TPH) and antioxidant activity (AO). This study aimed to estimate quality in sugary (su1) sweet corn hybrids based on the maximum content of kernel chemical compounds and the content change during maturation. During two growing seasons, five harvests by year were made at 2-day intervals from 17 to 25 days after pollination (DAP). KM decreased among hybrids from 6.6% to 14% over an eight-day period, or 0.8% to 1.8% per day. TS content was the highest at 17 DAP (16.5–28.7 mg/g DW) and decreased during maturation from 27% to 67%. Hybrids differed significantly in TPH at 17 DAP (204.4–357.1 mg GAE/100 g DW). TPH change during maturation ranged from the no significant differences up to a 29.3% decrease. DPPH- radical scavenging activity ranged among genotypes from 52.5% to 74.9% inhibition at 17 DAP and significantly increased during maturation. A well-defined hybrid-specific harvest window is necessary to maintain kernel quality in su1 sweet corn