Weed management in soybean with a special focus on the control of purple nutsedge (Cyperus rotundus)

Purple nutsedge (Cyperus rotundus L.) is globally an important perennial weed. Infestations from this species lead to significant losses in yield and quality of crop production. A field study was conducted at Kopaida region in Greece, to evaluate the efficacy of different herbicides for the weed management in soybean. The evaluation of the herbicides was based on the efficacy against purple nutsedge and the effect on soybean biomass production and crop seed yield. Treatments included an untreated control, two pre-emergence applications (with S-metolachlor and pendimethalin), as well as three post-emergence applications (with trifloxysulfuron, bentazone and pyrithiobac sodium). A single application of S-metolachlor maintained the density of purple nutsedge at 15 plants per m2 in soybean and allowed the crop to compete adequately with the weed. S-metolachlor also resulted in a seed yield of 3.26 tn ha-1 , a value 52% higher than the untreated control and 38–45% higher than the other herbicides. The results from this study demonstrated that a combination of high seed density in soybean and effective application of herbicides like S-metolachlor can lead to economically acceptable yields

The effect of nitrogen fertilization on root characteristics of Camelina sativa L. in greenhouse pots

Climate change has made mandatory the introduction of new crops in Greece, such as the cultivation of camelina [Camelina sativa (L.) Crantz]. Nitrogen (N) and the development of root system are two important factors affecting crop growth and yield. Camelina has been studied mainly for its composition and oil. In the present study, root development of camelina crop was thoroughly investigated; mainly in terms of Nitrogen fertilization. Therefore, a camelina greenhouse experiment was established in Western Greece, in the region of Agrinio, in March 2019 in completely randomized design with four treatments, (control 0 ppm N, 30 ppm N, 60, ppm N and 90 ppm N). The N rates had statistically significant affected root density and root surface from 40 to 120 days after treatment (DAT) with highest values at 100 DAT and 90 ppm N, 52.54 cm of root 100 cm-3 and 27.59 cm2 of root 100 cm-3 , respectively. The root volume was significantly affected by N fertilizer from 40 to 100 DAT and highest value was 13.18 cm3 of root 100 cm-3 soil in the 90 ppm at 120 DAT. The plant leaf area was significantly affected by the highest rate of N. Yield per plant had not statistically significant difference with the 60 and with the 90 and highest weight per plant 292.25 g plant-1 in 90 ppm. In conclusion, Ν fertilization significantly affected growth or camelina’s root system after 40 DAT. Plant growth was significantly affected by fertilization and the highest yield and 1,000 seed weight were recorded with the highest amount of N

Seed and Saponin Production of Organic Quinoa (Chenopodium quinoa Willd.) for different Tillage and Fertilization

Field experiment was conducted to determine the effects of tillage systems and fertilization on growth, yield and quality of quinoa crop (Chenopodium quinoa Willd.). The experiment was laid out in a split-plot design with four replicates, two main plots [conventional tillage (CT) and minimum tillage (MT)] and three sub-plots (fertilization treatments: control, cow manure and compost). The soil porosity (45.5-49.75%) and total nitrogen (0.144-0.173%) were higher in soils subjected to MT system than under CT. In soil porosity, an interaction between fertilization and tillage system was found. The highest leaf area index (4.47-5.03), dry weight (8650-9290 kg ha-1) and root density (1.03-1.21 cm cm-3) were also found in MT. Moreover, there were significant differences between the organic fertilization treatments concerning the LAI, dry weight and root density. The highest seed yield (2485-2643 kg ha-1) and saponin content (0.42-0.45%) were found in cow manure and compost treatments. Also, the highest saponin yield (7.70-12.05 kg ha-1) was found in the MT system. Saponin yield had positive and significant correlation with total N (r=0.866, p<0.001). In quinoa measurements, an interaction between fertilization and tillage system was not found. The present results indicated that MT and organic fertilization increase saponin yield of quinoa

Effects of cropping system (organic and conventional) on the fiber quality index, spinning consistency index and multiplicative analytic hierarchy process of cotton (Gossypium hirsutum L.)

Markets for organically produced high quality cotton (Gossypium hirsutum L.) are projected to increase. Field experiments were conducted in Palamas, Karditsa in Central Greece, to compare the effects of two cropping systems on fiber quality of three cotton cultivars. The experiments, conducted during three years, were laid out in a split plot design with four replicates, two main plots (organic and conventional system) and three sub-plots (cotton cultivars). Findings suggest that fiber quality index (FQI), spinning consistency index (SCI) and multiplicative analytic hierarchy process (MAHP) are three indices that could be integrated in a useful protocol for the evaluation of different cropping systems for cotton cultivation. In particular, our results indicate that in general there was not any superiority of conventional compared to the organic cropping system regarding fiber quality as shown by the above mentioned indices. Regarding the length of the cotton fiber, this was positively correlated with micronair and the uniformity index of the cotton fiber. The organic system resulted to higher values of SCI than the ones of the conventional (1547.9 and 1522.3, respectively). The present 3-years study shows that organic cultivation of cotton can ensure high fiber quality and this was clearly confirmed by means of the several important indices

Effect of Tillage System and Rimsulfuron Application on Weed Flora, Arbuscular Mycorrhizal (AM) Root Colonization and Yield of Maize (Zea mays L.)

Field experiments were conducted to determine the effects of tillage system and rimsulfuron application on weed flora and growth of maize (Zen mays L. Mitic F1) at a site with no history of pesticide use for the last 5 years. A randomized complete block design was employed with three replicates per treatment (conventional tillage without rimsulfuron application (control), no-tillage with rimsulfuron application (NT+Rim) and conventional tillage with rimsulfuron application (CT+Rim)). The lowest leaf area index, dry weight and yield of maize were recorded in NT+Rim plots. In addition, the highest soil bulk density was determined in NT+Rim plots. Moreover, the rimsulfuron application resulted in significant reduction in the root growth and arbuscular mycorrhizal (AM) colonization. The lowest root biomass, root length density, root surface and AM root colonization was found in CT+Rim plots. The lowest weed number and biomass was also observed at CT+Rim plots. Sustainability yield index (SYI) shown that the maize crop is more stable under conventional tillage compared with no-tillage. Our results indicated that root growth was reduced significant by rimsulfuron application but statistically significant lower maize yield was obtained in no-tillage system

Effects of nitrogen fertilizers with two different inhibitors (urease and nitrification) on the survival and activity of earthworms (Octodrilus complanatus)

Earthworms are among the most important species of the soil macrofauna. However, they are very sensitive to inorganic fertilization, more specifically to urea, which makes them a well-known bio-indicator. The objective of this study was to test if a fertilizer with inhibitors could be less destructive to earthworms than urea. In two consecutive years, we studied how new type fertilizers with urea (urea + urease inhibitor, urea + nitrification inhibitor and urea + urease inhibitor + nitrification inhibitor) can differ from urea applied alone and be closer to control (no fertilizer) in terms of the impact on earthworms, verified on different days after application. The measurements concerned earthworms’ mortality, casts and weight. Moreover, some soil properties which are affected by earthworms’ activity, such as exchangeable Ca, cation exchange capacity (CEC) and soil CO2 respiration, were studied. The inhibitors that were used comprised nitrification inhibitor, dicyandiamide (DCD), urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT), and double inhibitors, both urease and nitrification inhibitor. The study revealed how a fertilizer with inhibitors could be less destructive to earthworms than urea. Urea with urease inhibitor and urea with urease inhibitor and nitrification inhibitor had the least negative impact on earthworms’ activities. In contrast, urea and urea with nitrification inhibitor caused higher mortality among earthworms than the other fertilizers used

Energy inputs, output and productivity in organic and conventional maize and tomato production, under mediterranean conditions

Maize (Zea mays L.) and tomato (Solanum lycopersicum L.) are two important crops in Mediterranean countries. The objectives of this study were to evaluate the differences and similarities in energy flow between conventional and organic tomato and maize crops. Our results indicated that the total energy input in the conventional system was higher than in organic system and for individual crops was 25.90 and 29.34% higher for tomato and maize, respectively, than the organic system. Of the inputs for the different operations, fertilizers consumed the bulk of the energy for all crops. In maize crop, human labour had little impact on total energy use both in organic and conventional system. In addition, seed inputs in maize production had corresponded to 11.44% of the total energy requirement. Concerning the pesticides inputs, there were significant difffferences between organic and conventional systems. In both crops, the pesticides energy input was higher in conventional production compared to organic system. Moreover, irrigation inputs were 13-23% of the total energy use in the organic system and 12-20% in the conventional system. In both crops, the energy output and energy productivity were also higher in conventional production compared to organic system. Our study shows that the adoption of organic cultural system could reduce energy inputs

Efficacy and selectivity of pre- and post-emergence herbicides in chia (Salvia hispanica L.) under mediterranean semi-arid conditions

In the present study, the selectivity and efficacy of several post and pre-emergence herbicides in chia (Salvia hispanica L.) were examined. Field experiments were conducted at two locations with different soil types and environmental conditions. Our results showed that the pre-emergence application of pendimethalin, oxyfluorfen and linuron reduced total weed density by 71-74%, 74-82% and 53-55%, respectively. Despite their high effectiveness against specific weed species, the abovementioned herbicides had a negative effect on plant density and biomass yield. In addition, herbicides bentazon and fluazifopp- butyl which applied post-emergence did not affect significantly plant height and biomass yield. In conclusion, the herbicides linuron, pendimethalin and oyxfluorfen do not seem to be a viable option for weed control in chia crop, whereas the postemergence applied herbicides did not affect significantly plants' growth. Further evaluation of chia tolerance to herbicides is needed under different application rates in order to make safe suggestions for chemical control of weeds. © 2018 Academic Press