Comparison of total phenolic content and composition of individual phenolic acids in testae and testa-removed kernels of 15 Valencia-type peanut (Arachis hypogaea L.) genotypes

A successful peanut breeding to obtain genotypes with greater phenolic content requires information on type and content of phenolic compounds in parental peanut genotypes. The aim of this study was to investigate the total phenolic contents and phenolic acid profiles of 15 Valencia-type peanut genotypes both in peanut testae and testa-removed kernels (cotyledons and embryonic axes). Total phenolic content and phenolic acid profiles were analyzed using Folin-Ciocalteu method and high-performance liquid chromatography (HPLC),  respectively. The total phenolic contents of testae and testa-removed kernels varied from 2.47 ± 0.96 to 84.53 ± 5.57 and 0.07 ± 0.01 to 0.12 ± 0.01 mg gallic acid equivalent (GAE)/g dry weight, respectively. Testae of  KK4 and ICG14710 genotypes had the greatest and least total phenolic content, respectively. The peanut  testae with pink color (NM044, NM071, ICG15042 and KK4) had significantly greater phenolic content than those with gray (ICG397 and ICG14710) and yellow (NM001) colors. The present study demonstrates that  p-coumaric and vanillic acids were the two predominant phenolic acids in the testae of nearly all peanut  genotypes tested, except for KK4 genotype whose predominant phenolic acid in its testa was  p-hydroxybenzoic acid. All the testa-removed kernels tested contained significantly greater amount of  p-coumaric acid than other identified phenolic acids. These results would be useful for peanut breeding to  obtain peanut genotypes with greater phenolic acid and other favorable traits.Key words: Valencia peanuts, peanut testae, phenolic acids, p-coumaric acid, vanillic acid

Simple sequence repeat (SSR)-based genetic variability among peanut genotypes different in specific leaf weight and relative water content

The objective of this study was to compare if simple sequence repeat (SSR) markers could correctly identify peanut genotypes with difference in specific leaf weight (SLW) and relative water content (RWC). Four peanut genotypes and two water regimes (FC and 1/3 available water; 1/3 AW) were arranged in factorial randomized complete block design with six replications. The data were recorded for specific leaf weight (SLW) and relative water content (RWC), and 256 SSR markers were used to detect genetic difference. 89 SSR markers could detect polymorphism among peanut genotypes (48.9%). The numbers of alleles ranged from 1 to 6 with a mean of 2.7 alleles per locus. The polymorphic information content (PIC) values varied from 0.38 to 0.75 with a mean of 0.48. The genetics relationship among peanut genotypes was estimated. KK 4 was clustered distinct from the others genotypes, whereas ICGV 98324 and ICGV 98303 were grouped in the same cluster furthest from the KK 4. The results from this study could be useful as a source of variation for development of mapping population for drought tolerance in peanut breeding program.Keywords: Drought, water regime, polymorphism, genetic relationship, SSR markersAfrican Journal of Biotechnology Vol. 12(26), pp. 4053-4064, 26 June, 201

Gibberellic acid effect on tuber dormancy of Jerusalem artichoke under greenhouse conditions

Tuber dormancy of Jerusalem artichoke (Helianthus tuberosus L.) is an important factor hindering breeding progress and production as Jerusalem artichoke tubers do not germinate uniformly and environmental conditions greatly affect germination. Freshly-harvested tubers are normally used for planting of a subsequent crop, and low germination is a problem. The experiments were conducted in greenhouses at Khon Kaen University, Thailand and at Iowa State University, USA to explore other innovative methods to improve germination of Jerusalem artichoke seed tubers. The objective of this study was to determine the effects of Gibberellic acid (GA) on the dormancy of Jerusalem artichoke seed tubers. GA at all concentrations increased germination percentage, shoot length and shoot dry weight of seed tubers. All the varieties of Jerusalem artichoke germinated uniformly under various GA treatments between 4.5 and 8.0 days after planting. The highest rate of germination was noted for GA at a concentration of 1%

Relationship between chlorophyll density and spad chlorophyll meter reading for Jerusalem artichoke (Helianthus tuberosus L.)

Chlorophyll is an indicator of crop health and productivity. Measuring chlorophyll is usually done directly and requires significant time and resources. Indirect measurement of chlorophyll density using a handheld portable chlorophyll meter can reduce time. However, this information is very limited for Jerusalem artichoke. The objectives of this study were to examine the stability of chlorophyll density and SPAD chlorophyll meter reading (SCMR) and to evaluate the relationships between chlorophyll density and SCMR for different plant genotypes, at different plant ages and planting dates. Three Jerusalem artichoke varieties were evaluated for chlorophyll density and SCMR in a greenhouse at 13 planting dates from September to March in 2008/09 and repeated in 2009/10. The treatments were replicated four times. The chlorophyll density and SCMR evaluation were carried out at 30, 60 and 90 days after transplanting (DAT). Differences among planting dates were observed for chlorophyll density and SCMR. Evaluation at 30 DAT could best discriminate the differences in chlorophyll density and SCMR among Jerusalem artichoke genotypes. High and consistent association between chlorophyll density and SCMR was found across planting dates. SCMR can be used as a surrogate trait for chlorophyll density to screen a large number of accessions in Jerusalem artichoke breeding program for high levels of chlorophyll density

Types of gene effects governing the inheritance of oleic and linoleic acids in peanut (Arachis hypogaea L.)

Oleic and linoleic acids are major fatty acids in peanut determining the quality and shelf-life of peanut products. A better understanding on the inheritance of these characters is an important for high-oleic breeding programs. The objective of this research was to determine the gene actions for oleic acid, linoleic acid, the ratio of oleic to linoleic acids (O/L ratio) and percentage oil (% oil) in peanut. Georgia-02C, SunOleic 97R (high-oleic genotypes) and KKU 1 (low-oleic genotypes) were used as parents to generate P1, P2, F2, F3, BC11S and BC12S. The entries were planted in a randomized complete block design with four replications in the rainy season (2008) and the dry season (2008/2009). Gas liquid chromatography (GLC) was used to analyze fatty acid compositions. The data were used in generation means analysis to understand gene effects. The differences in season, generation and generation X season interactions were significant for oleic acid in the crosses Georgia-02C X KKU 1 and SunOleic 97R X KKU 1. Additive, dominance and epistasis gene effects were significant for oleic acid, linoleic acid, O/L ratio and % oil. Initial selection can be carried out in early segregating population, and final selection in late generations.Keywords: Breeding, gene actions, generation mean analysis, groundnut, oil qualit

Root responses of Jerusalem artichoke genotypes to different water regimes

The objective of this study was to determine effects of drought on selected root growth parameters and develop relationships between root parameters and tuber yield for selected Jerusalem artichoke (JA) genotypes. Three water regimes (Field capacity, 50% available soil water (AW) and 25% AW) and five JA varieties (JA 60, JA 125, JA 5, JA 89 and HEL 65) were planted with factorial treatments in a randomized complete block design with four replications. Data on root dry weight (RDW) and root: shoot ratios (RSR) were measured manually. Root diameter (RD), root length (RL), root surface area (RSA) and root volume (RV) were collected at harvest. Drought tolerance indices (DTI) were calculated for all root parameters. Drought reduced all root parameters and DTI but increased RSR in JA 60, JA 125, JA 5, and HEL 65. JA 125 had high values for all root traits and DTI of these traits under drought stress. JA 60 had high DTI of RDW, RD and RSR under mild and severe water stress. JA 5 had high DTI of RDW, RD, RL, RSR and RV under drought conditions. JA 89 and HEL 65 performed well for RDW, RD, RL and low DTI of all root characteristics. DTI for root parameters were positively correlated with tuber dry weight under mild and severe water stress. The JA 5, JA 60 and JA 125 varieties showed high DTI for some root traits, indicating that better root parameters contributed to higher tuber yield under drought stress

Photoperiod and growing degree days effect on dry matter partitioning in Jerusalem artichoke

The effect of photoperiod and growing degree days (GDD) on dry matter and dry matter partitioning in Jerusalem artichoke was investigated during 2008-09 and 2009-10. Three Jerusalem artichoke genotypes (CN-52867, JA-89 and HEL-65) were planted in 15 day-intervals between with thirteen different dates (September 20 to March 20) at Khon Kaen University, Thailand. Jerusalem artichoke genotypes responded differently to varying planting dates for harvest index, shoot dry weight, leaf area, number of tubers and tuber size. Two genotypes, CN-52867 and JA-89, were significantly more productive on the planting date of 20 September and they also performed well on planting dates of 5 October to 20 March. Plant grown in long photoperiod with a higher number of GDD produced shoot dry weight rather than greater number of harvestable tubers, while short photoperiod induced high partitioning of assimilates to harvestable tubers. Jerusalem artichoke plants grown during short photoperiod were smaller and produced larger tubers than those grown during long photoperiod. Tuber yield was relatively unchanged across planting dates. Since Jerusalem artichoke during short photoperiod had smaller plants, growing Jerusalem artichoke at higher plant population with optimum density is highly recommended to increase tuber yield. The information obtained in this study is extremely important for Jerusalem artichoke production and breeding in the tropical agro-climatic conditions such as Thailand

Genotypic variability for tuber yield, biomass, and drought tolerance in Jerusalem artichoke germplasm

Jerusalem artichoke could be an alternative feedstock for bioenergy during times when there are shortages of other raw materials for the ethanol industry. However, insufficient water under rainfed conditions is a major cause of Jerusalem artichoke losses. Genetic variation for drought tolerance is an essential prerequisite for the development of Jerusalem artichoke cultivars with improved drought tolerance. The objectives of this study were to determine the effects of drought stress on tuber dry weight and biomass and to investigate the genotypic variability in Jerusalem artichoke germplasm. The line-source sprinkler technique was used to compare moisture responses of a range of 40 Jerusalem artichoke genotypes grown using 3 water levels. Experiments were conducted on a Yasothon soil series in Northeast Thailand during 2010/11 and 2011/12 and included extended dry periods. Drought reduced tuber dry weight and biomass, and the reductions in tuber dry weight and biomass were greater under severe drought than moderate drought conditions. Over both seasons, CN 52867, HEL 53, HEL 231, HEL 335, JA 76, HEL 65, and JA 102 × JA 89 (8) had consistently high tuber dry weight (1.3 to 4.5 t ha-1) and HEL 53, HEL 61, HEL 231, HEL 335, JA 76, JA 15, JA 89, HEL 65, HEL 256, and JA 102 × JA 89 (8) had consistently high biomass (2.0 to 6.8 t ha-1). These Jerusalem artichoke genotypes are promising parents in breeding for drought tolerance

Pre-chill with gibberellic acid overcomes seed dormancy of Jerusalem artichoke

Jerusalem artichoke is a valuable source of inulin, a polysaccharide. Inulin is a sustainable source of dietary fiber that enhances the immune system in humans. Although Jerusalem artichoke can be propagated vegetatively, breeders use cross-fertilization to produce novel varieties and hybrids with higher inulin yields. Seed dormancy can hinder the breeding progress because dormancy reduces the number of generations a breeder can obtain in one year. Current methods for breaking seed dormancy are time-consuming, and usually involve removing or pin-pricking the seed coat of these very small seeds, or using several weeks of seed vernalization or several months of storage. Breeders thus require better methods that are less time-consuming and achieve higher germination percentages. Here we studied germination, dormant seed, dead seed and the seedling growth rate of different Jerusalem artichoke genotypes and seed lots after seeds were treated with different methods to break seed dormancy. We evaluated fresh and stored seed lots using the following treatments: seed samples were planted on top of media moistened with either potassium nitrate, gibberellic acid or distilled water as control. Two identical sets of samples were planted: one set was germinated in a chamber at alternate 15−25 °C for 28 days, while the second set was prechilled at 5 °C for 14 days, before moving the samples to the alternate 15−25 °C chamber for 14 days. Our findings reveal that the highest germination percentage up to 85.3% was obtained when applying pre-chill with gibberellic acid. This novel dormancy-breaking treatment was thus effective in promoting fresh seed germination

Influence of planting date and temperature on inulin content in Jerusalem artichoke (Helianthus tuberosus L.)

Abstract Lower temperatures during the dry season in tropical regions might affect inulin content and inulin yield of Jerusalem artichoke. The objective of this study was to determine the effect of planting dates during low temperature on inulin yield and content of Jerusalem artichoke. Two pot experiments were conducted during the dry seasons 2008/09 and 2009/10. Three genotypes were grown at seven planting dates. Planting Jerusalem artichoke during lower temperature periods (10-16 °C) reduced total dry weight and inulin content, whereas inulin content increased when planted during warmer periods (21-31°C). Jerusalem artichoke could be grown in all planting dates, but the most appropriate planting dates were in March. November to January should be avoided because the plants showed severe stunting with these planting dates. Moderate relationships between temperature sums and inulin content were observed in 2008/09 (r = 0.64; P < 0.01) and 2009/10 (r = 0.61; P < 0.01). The results revealed that temperature was important for producing high tuber yield having high inulin during the dry season in tropical regions