نشریه نهال و بذر
سال سی و هشتم شماره 2 (تابستان 1401)

The aim of the present study was to evaluate and interpret the genotype × environment interaction for advanced rainfed lentil lines. Fifteen advanced rainfed lentil lines (genotypes) along with two commercial cultivars (cv. Gachsaran and cv. Sepehr) as check were evaluated using randomized complete block design with three replications in Gachsaran, Moghan, Khorramabad and Ilam field stations in Iran in 2019-20 and 2020-21 cropping seasons. The mean seed yield of trials was 891 kg ha-1. Genotype 10 with 1031 kg ha-1 had the highest mean seed yield, and genotype 16 (cv. Gachsaran) with 728 kg ha-1 had the lowest. Since genotype × environment interaction was significant, yield stability analysis was performed. Evaluation of the seed yield stability of genotypes by rank method showed that genotypes 12 and 10 had high seed yield and yield stability. In addition, yield stability analysis using WAASB index, as a multivariate method, was also performed. The seed yield × WAASB index biplot showed that most of the lentil genotypes had higher seed yield and yield stability than the check cultivars (cv. Gachsaran and cv. Sepehr). Genotypes 12, 13, 11, 10 and 1 had higher seed yield and yield stability than the superior check cultivar (cv. Sepehr). Considering the equal contribution for mean seed yield and yield stability in the calculation of WAASBY index, genotypes 10, 13, 11, 12, 1 were ranked as the most desirable genotypes for target environments.

Evaluation of the Dickson quality index (DQI) is an efficient but destructive and time-consuming method for prediction of the quality of different seedlings. Fast and low-cost prediction of the quality and vigor of fruit tree seedlings at harvest time using DQI which has shown to be highly correlated with morphological characteristics, is necessary. In this study, grafted sour cherry and sweet cherry bare-root seedlings of 17 commercial cultivars with three replications from 10 nurseries in four provinces in Iran were harvested during the transplanting seasons of 2020 and 2021. The seedlings were selected from two types of certified and non-certified grafted sour cherry and sweet cherry on the seedling and clonal rootstocks, respectively. Seedling height, diameter above grafting line (DAGL), root length, number of roots and branches, fresh and dry weight, height to diameter ratio, and DQI were assessed, and simple correlation coefficients between them were calculated. Path analysis method employed to estimate direct and indirect effects of variables. The results showed that the average DQI for non-certified seedlings was 15.6. The higher values of DQI were observed in areas with more than 3400 accumulated growing degree-days. For certified seedlings, DQI decreased to 12 which is likely to be the effect of using SL64 semi-dwarf rootstock. Based on the results of the path analysis for DQI, the highest direct effect was related to DAGL. DAGL was determined as the most efficient morphological characteristic for characterization of quality categories of grafted sour cherry and sweet cherry seedlings due mainly to its highest correlation with the DQI and most of the other morphological characteristics.

To study the effect of different levels of nitrogen and potassium fertilizers on grain yield and quality properties of durum wheat cultivars, a field experiment was carried out in the research filed of the Seed and Plant Improvement Institute in Karaj, Iran, in 2019-20 and 2020-21 cropping seasons. Split plot arrangements in randomized complete block design with three replications was employed to assess the effect of nitrogen and potassium fertilizers levels on grain yield and quality properties of two durum wheat cultivars. Two durum wheat cultivars (Hana and Sana) were assigned to main plots, and different levels of urea and potassium sulfate fertilizers (control, 200, 300, 400 kg ha-1 urea (N) and each level of nitrogen fertilizer with 100 and 200 kg.ha-1 potassium sulfate (K)) were randomized in sub-plots. The results showed that the effect of year and different fertilizer levels on grain yield was significant (P ≤ 0.01). The grain yield increased by increasing nitrogen and potassium fertilizer levels. It was notable that the simultaneous application of these two fertilizers showed greater effect on grain yield. Therefore, grain yield at 300 kg ha-1 of urea fertilizer plus 200 kg ha-1 of potassium sulfate fertilizer was higher than sole 400 kg ha-1 urea fertilizer. Quality properties included; hectoliter weight, grain protein content, zeleny sedimentation volume, grain hardness index, grain wet gluten content, gluten index, SDS sedimentation height, semolina extraction rate and grain yellow berry percentage. The combined analysis of variance showed that there was significant differences among different fertilizer levels for all grain quality properties, and between years for wet gluten content, grain hardness, semolina extraction rate and grain yellow berry percentage. Wet gluten content, grain hardness and semolina extraction rate in 2019-20 were higher than in 2020-21 cropping season. Whereas, grain yellow berry percentage was higher in 2020-21 cropping season. In General, increasing the rate of fertilizers application increased all quality properties except grain yellow berry percentage that decreased by 76% at 400 kg ha-1 urea plus 200 kg ha-1 potassium sulfate as compared with control. It is concluded that application of 400 kg ha-1 urea plus 200 kg ha-1 potassium sulfate could be sufficient for optimizing grain yield and quality properties of durum wheat in Karaj region.

Tolerance to deficit irrigation and related mechanisms are very important characteristics of seedling and clonal pear rootstocks for successful commercialization. In this study, seedling rootstocks, Dargazi and Pyrus betulifolia Bunge, and clonal Pyrodwarf, OH×F69 and OH×F87 rootstocks for tolerance to deficit irrigation as well as enzymatic anti-oxidative mechanisms in response to the stress was evaluated under greenhouse conditions at temperate fruits research center, Horticultural Science Research Institute, Karaj, Iran, in 2018. The deficit irrigation stress applied at three levels: control, mild and severe by irrigation at 100, 75 and 50 percent of field capacity (FC), in greenhouse during 60 days. Rootstock heights, generation of hydrogen peroxide (H2O2), electrolyte leakage and the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (POX) were assessed at 30 and 60 days following the application of deficit irrigation stress. The results showed that Pyrodwarf rootstock had greater tolerance to deficit irrigation stress, even at 50% FC. The generation of H2O2 was between 23.7 μM g-1 of fresh weight in OH×F87 and 32.5 in P. betulifolia Bunge. However, as the deficit irrigation stress severity and duration increased, the H2O2 level enhanced to its maximum of 81.3 μM g-1 of fresh weight, and was highly correlated (r = 0.734**) with electrolyte leakage. In addition, the calculated correlation coefficients confirmed the order of increase in the activity of SOD and then CAT in response to the increase in the intensity of deficit irrigation stress. Based on the results of this study, tolerance mechanisms to deficit irrigation stress in pear rootstocks is partly attained by converting superoxide into hydrogen peroxide (H2O2), followed by preventing its accumulation.

To assess root and white sugar yield stability of 11 spring sugar beet genotypes together with three check cultivars, a field experiment was carried out using randomized complete block design with four replications in six agricultural research stations; Toroq (Mashhad), Zarghan, Khoy, Kermanshah Miandoab, and Karaj, Iran, in 2020 and 2021. Combined analysis of variance showed that genotype × environment interaction was significant (P < 0.01), and genotypes had different performance in different environmental conditions. Based on regression coefficient, deviation from regression, Shukla’s stability variance, Wrick's ecovalence, and coefficient of determination, GB-6 and GB-10 genotypes were identified with high root and white sugar yield and yield stability. Although the number of genotypes with yield stability increased by using superiority measure and coefficient of variation, three genotypes including; GB-11, GB-10, and GB-2 showed the highest yield stability for root and white sugar yield, respectively. Using GGE biplot method, GB-11, GB-10, GB-2 and GB-6 were identified with higher root and white sugar yield, than average of all genotypes, and higher yield stability, respectively. Considering the results of this research, GB-6, GB-11, GB-2, and GB-10 were identified as high-yielding genotypes with high yield stability.

To quantify the role of crop management practices on seed yield of soybean in Gorgan, 120 soybean farmers’ fields with different sowing dates and different management practices were randomly selected in Gorgan region in the north of Iran, in 2016, 2017 and 2018. Qualitative information was transformed to quantitative data. By using stepwise regression analysis a seed yield model was selected with two parameters including; delay in sowing date and number of irrigation during soybean growing season. The selected model explained 81% of the variation for seed yield. The model showed the importance of sowing date and irrigation for increasing seed yield of soybean in farmers’ fields in Gorgan region. There was negative significant linear relationship between biological and seed yield with delay in sowing date that explained 64% and 70% of the variation for these two characteristics, respectively. Each day delay in sowing date from May 22, biological and seed yield decreased 130 and 56 kg ha-1, respectively. The mean seed yield of farmers’ fields, with 0, 1, 2, 3, 4, 5 and 6 irrigation during growing season, was 955, 883, 1066, 1995, 1990, 2665 and 3769 kg ha-1, respectively. In Goragan region, soybean is planted usually from late may following harvest of winter crops such as wheat and canola. Under these environmental conditions, optimum crop management practices are required in soybean farmers’ fields to achieve high seed yield and sustainable production.