Iranian Journal of Crop Sciences
Year:2018 | Volume:20 | Issue:3|Papers Count:6

Terminal heat sterss considered as one of the major challenges of winter production of potato in warm areas of the country including the south of Kerman provience. To determine the suitable strategy for mitigating terminal heat stress injury, a split-split plot experiment based on randomized complete block design with three replications was conducted in South Kerman Agricultural Research and Education Center (Jiroft), Iran, for 2 years (2013 and 2014). The main factor was heat stress: normal (on time planting; Dec. 31) and terminal heat stress (late planting; Feb. 4) and three potato cultivars; Satina, Sante and Milva and four calcium applications; (without calcium nitrate application, foliar application of 2500 mg. l-1 calcium nitrate in two and three stages and soil application of 75 kg. ha-1 calcium nitrate in two stages) were in sub and sub-sub plots, respectively. Results showed that heat stress reduced marketable yield and the weight and number of marketable tubers per plant. Sante and Satina cultivars produced the highest marketable tuber yield in normal condition (47. 15 and 44. 9 ton. ha-1, respectively), but under heat stress conditions, the difference between marketable tuber yield of those cultivars was not significant. The application of calcium nitrate improved marketable, non-marketable and total tuber yield and its components in potato cultivars and soil application of 75 kg. ha-1 of calcium nitrate was significantly suprior than the other treatments. The interaction effect of terminal heat stress and calcium nitrate applications on marketable and total tuber yield, mean weight and number of marketable and non-marketable tuber was significant. Soil application of calcium nitrate (75 kg. ha-1) increased marketable tuber yield of potato cultivars under normal and terminal heat stress conditions (10. 5 and 24. 5%, respectively) that revealed the mitigating effect of calcium nitrate on terminal heat stress in potato cultivars. It concluded that soil application of calcium nitrate seems to be an appropriate method to reduce the adverse effects of terminal heat stress in winter potato production.

To determine the best sowing time and cultivar of forage sorghum in summer cropping as a substitute for maize under water deficit conditions in the temperate region of Koohdasht, Lorestan, Iran, a split plot experiment in randomized complete block design layout was conducted with four replications and four planting times (June 25 and 2th, 9th and 16th July) (after wheat harvest) and two forage sorghum cultivars (Pegah and Speedfeed) in main and sub plots, respectively, in the summer of 2013 and 2014 at Lorestan Agricultural and Natural Resources Research and Education Center, Khorramabad, Iran. Results showed that delayed planting reduced dry matter accumulation and crop growth rate (CGR) and Pegah cultivar performed better than Speedfeed cultivar. Maximum plant height was achieved in Speedfeed cultivar in second planting time in first and second years (173. 3 and 211. 6 cm, respectively). Pegah cultivar had better performance than Speedfeed in leaf area index and stem diameter in most planting times. Pegah cultivar in first planting time had highest fresh forage yield (94. 0 and 110. 2 ton. ha-1 in first and second years, respectively) and delay planting reduced dry and fresh forage yield. It concluded that the maximum dry and fresh forage yield of sorghum (cv. Pegah) could be produced in June seed sowing and seems to be more suitable for temperate regions like Koohdasht, Lorestan, Iran.

Salinity stress is one of the important abiotic stresses affects crop production worldwide. To identify barley lines with stable and acceptable grain yield under salinity stress, field experiments were conducted in Isfahan, Birjand and Yazd, Iran, at salt affected Agricultural Research stations (totaly at six environments) using 18 barley promising lines along with two checks (Khatam cultivar and MBSYT91-8 line) in 2014-2016 cropping seasons. Results of combined analysis variance for grain yield showed that the effect of genotype and year×location, genotype×year and genotype×year×location were highly significant. Results of non-parametric and AMMI analysis showed that the lines; 1, 6 and 8 were superior lines according to yield mean, yield standard deviation, rank mean, rank standard deviation and yield index ratio. According to the results of AMMI analysis, using IPCAs score, AMMI stability value and proposed genotypes for each environment the lines; 6 and 8 were identified as stable lines with acceptable grain yield. In AMMI analysis two first IPCAs were significant and explained 46. 2% and 22. 1% of the total grain yield variation, respectively. According to the results of the two methods, line 8, showed general compatibility for studied sites and similar regions and line 6 showed specific compatibility for Birjand and Isfahan and line 19 for Yazd.

To evaluate the effects of deficit irrigation and super absorbent application on physiological traits and seed yield of new sunflower hybrids, a field experiment was conducted in split plot factorial layout based on randomized complete block design with three replications in Agricultural Research Station of Islamabad-e-Gharb, Iran, during cropping seasons 2011 and 2012. Treatments were irrigation levels including; normal irrigation (irrigation at 25% soil moisture depletion of field capacity), irrigation at 50% soil moisture depletion of field capacity (moderate drought stress), irrigation at 75% soil moisture depletion of field capacity (severe drought stress) as main plots and sunflower hybrids (Farokh, Ghasem and Shams) along with super absorbent application (0, 100 and 200 kg. ha-1) as subplots, were arranged in factorial layout. Results of combined analysis of variance showed that the interaction effect of deficit irrigation hybrids on all plat traits and super absorbent hybrids on all plant trraits (except for osmotic adjustment and cell membrane stability) and deficit irrigation super absorbent o all plant traits (except for seed yield and cell membrane stability), were significant. Under severe drought stress condition, Farokh hybrid with 3071 kg. ha-1 was superior compare to Shams and Ghasem hybrids (with 2710 and 2601 kg. ha-1, respectively). Under severe drought stress codition, the application of super absorbent increased relative water content, free proline, proteins and soluble sugars content in sunflower hybrids, but reduced osmotic adjustment. It concluded that the application of super absorbent may relatively mitigate the adverse effects of drought stress on physiological traits of sunflower. Under drought stress condition, Farrokh hybrid along with application of super adsorbent (200 kg. ha-1) was superior in all plant traits compared to other hybrids.

To study the stability of seed yield of winter oilseed rape genotypes in target areas and to compare the types of stability parameters, experiments were conducted in randomized complete block design with 15 genotypes and a control cultivar (total of 16 genotypes) with three replications during the two growing seasons of 2015-2017 in four cold and semi cold locations (Kabutarabad-Isfahan, Torogh-Mashhad, Islamabad-e-Gharb, Karaj), Iran. Results of analysis of variance showed a significant difference between the oilseed rape genotypes in some locations. After confirming the homogeneity of variance of experimental errors in different environments, combined analysis of variance was performed with the assumption of the fix effect of genotypes and random effect of location and year. Results showed that the environment, genotype and genotype×environment effects were significant at 1% probability level and genotypes had different performance in different environments. The greatest contribution of the variations was related to the environmental effect (32. 83%). The statistical methods consisted of; environmental variation coefficient, stability variance, ecovalence, environmental variance, mean square deviations from regression line, coefficient of determination, regression coefficient Tai regression (Alpha and Lambda) and simultaneous selection index were used to determine the stable and high yielding genotypes. Although there was a possibility of selection for performance and stability by a functional criterion, but due to the existence of low and variable Spearman correlations between different types of indices, except for the simultaneous selection index and grain yield, a combination of different methods of stability was used and G4 (ES Alonso), G7 (Es Kamilo) and G16 (Okapi) genotypes were identified as stable and high yielding genotypes. It concluded that the selected genotypes could be used for cultivation in cold and mild cold regions of the country.

Improvement of forage quality is one of the important purposes of alfalfa breeding in order to develop cultivars with higher feeding values. The objective of this experiment was to evaluate of combining ability and heterosis for forage quality including; leaf to stem ratio, crude protein, soluble carbohydrate, ash, acid detergent fiber and neutral detergent fiber by GGE biplot graphical method. Selected partially inbred lines from the second generation selfing of eight alfalfa ecotypes were evaluated in a half-diallel cross design. Field experiments were performed in a randomized complete block design with three replications, included eight parents and 28 F1 at two locations, Karaj and Arak, Iran, during 2015-2016. Based on the results of Griffing method, mean square of GCA and SCA and SCA by environment interaction were significant for all the traits (p<0. 01) and GCA by environment interaction were significant for leaf to stem ratio (p<0. 05) and also for ADF and NDF (p<0. 01). GGE biplot graphical method showed the highest positive GCA for Silvana and the most negative GCA for Kozare and Rahnani for leaf to stem ratio, crude protein, soluble carbohydrate, ash. Nikshahri showed the highest positive GCA for acid detergent fiber and neutral detergent fiber as the unfavorable traits. SCA was the maximum for two specific parents; Ghahavand and Silvana for all the traits. Results revealed that there were proper diversity and heterosis for forage quality in alfalfa parents, so selfing and crossing between the partially inbreds (S2) could be possible by crossing between best single crosses to produce free hybrids to improve forage quality.