IRANIAN JOURNAL OF DRYLAND AGRICULTURE
Year:2017 | Volume:5 | Issue:2|Papers Count:7

Given the importance of wheat in human nutrition and its cultivation in large-area under rainfed in Iran, this study was aimed to evaluate the efficiency of artificial neural networks and linear multiple regression models to predict biomass and grain yields of wheat (cv. Sardari), in two-year study. In two stations (Koohrang and Ardal), 202 sampling points were selectedin the various hillslopes includes summit, shoulder, back slope, foot slope and toe slope. Atthe harvesting stage, the soil and plant samples were collected. Primary and secondary terrain attributes were extracted from digital elevation models, and meteorological data were used in two regions. Topography, 54 different soil characteristics, rainfall and management as the inputs as well as biomass and grain yields were considered as the outputs of both models. Artificial neural networks and multiple linear regression models, respectively, accounted for 84% and 15% of variations (R2) in grain yield prediction, and 76% and 6% in prediction of biomass yield. The root mean square error (RMSE) of the models also were equal to 0.033 and 0.092 to predict grain yield, and 0.037 and 0.102 to predict the biomass based on artificial neural network and multiple linear regression models, respectively. The results showed a better ability of artificial neural networks in comparison with multiple linear regression to estimate grain and biomass yields of wheat in the target areas.

This study was aimed to investigate the effects of sowing dates and weed interference on some qualitative and quantitative seed characteristics of chickpea cultivars. The experiment carried out as factorial split plot in randomized complete block design (RCBD) with three replications at research station of Kurdistan University in 2012-13. Sowing dates (autumn, Entezari and spring) and chickpea cultivars (Arman, Azad, Pirouz, ILC482 and Kaka) assigned to main plots as factorial and weed interferences (weeding and non-weeding) as subplots. Results showed that planting dates had significant effects on all studied traits. Weed competition resulted in severe reduction of seed number. In autumn sowing, weed interference reduced seed number by 78%. The reduction of seed numbers were77 and 99% in Entezari and spring sowing dates, respectively. Weed interference increased 100 seed weight as compared to weed free treatment.The highest seed yield observed in Entezari. ILC482 cultivar produced the highest seed yield (132.4 g/m-2). Under weed interference conditions, Kaka was the best grain yield. There was a significant difference between the cultivars for all seed quality traits, but ash, crude fiber and zinc content. The amount of phenolic compounds increased as growth period prolonged. The autumn and Entezari sowing dates were affected not only by cold stress but also encountered with more intense weed interference. Kaka had the highest amount of tannin.

Safflower (Carthamus tinctorius L.) is one of the valuable agricultural and industrial crops which cultivates in many parts of world. This study was aimed to evaluate the genetic variation of 31 spiny and spineless safflower genotypes provided from Dryland Agricultural Research Institute based on agronomic and morphological characteristics in cold rainfed conditions of Maragheh. Genotypes were evaluated in randomized complete blocks design with three replications. Descriptive statistics manifested the existence of genetic variability in the studied germplasm and the least amount of genetic diversity was belong to days to 50% flowering and days to maturity. Using principal component analysis showed that 6 components explained 91 percent of total variation. Biplot based on principal component analysis and dendrograms of cluster analysis revealed that all genotypes were classified into 2 groups. Maximum value of Mahalanobis distance between groups was 5.05. It can be concluded that there is remarkable genetic variability among safflower genotypes in cold rainfed conditions, which could be utilized in the screening of desirable parents and genotypes for safflower breeding programs.

In order to evaluate drought tolerance of lentil landraces at flowering stage, one split plot experiment in randomized complete block design with four replicates was conducted in agricultural faculty of Islamic Azad University of Tabriz in 2012-2013. Combined variance analysis showed genotype × drought stress interaction was significant in all investigated traits except to greening date, flowering date and plant height, which indicates different response of genotypes to drought stress for the studied traits. Three way interaction (year×genotype×drought stress) was not significant in all investigated traits, which indicates that drought stress for studied traits was similar in two years. Comparison of yield mean for genotype × drought interaction showed that all genotypes under drought stress had significant yield reduction in comparison with non-stress conditions, however, Shavi Varzeghan genotype in stress and non-stress conditions, showed better response than other genotypes. The drought tolerance indices (MP, GMP, HARM and STI) had positive and significant correlation with grain yield in stress and non-stress conditions in both two years. Based on these indices, Kalaybar, Garadagh, Horand Danehriz, Dagh Qayeh Gishlagy, Shavi Varzighan was identified tolerant genotypes to drought stress.

Wheat, as a major crop in Iran and in the world, is considered an important crop for human consumption. Identification of allelic variations at loci that control vernalization requirements and cold tolerance, provides valuable information for determining adaptability of wheat genotypes to target environments. At molecular level, vernalization in wheat (Triticum aestivum L.) is determined mainly by three VRN-1, VRN-2 and VRN-3 loci. In hexaploid wheat, dominant alleles Vrn-A1, Vrn-B1 and Vrn-D1 are responsible for spring growth habit and recessive allels with epistatic interactions determine the winter growth habit. In this study, allelic variations among 50 wheat genotypes were studied using 9 primer pairs specific to VRN-1 and VRN-B3 loci. Dominant alleles at Vrn-B1, Vrn-D1 and Vrn-B3 loci were detected with the frequency of %58, %24 and %90, respectively. Recessive alleles vrn-B1, vrn-D1 and vrn-B3 had a frequency of %42, %76 and %10, respectively. At Vrn-A1 locus, different alleles were detected with the frequency of Vrn-A1c (58%), Vrn-A1b (26%), Vrn-A1a (14%) and vrn-A1 (2%). Our finding revealed a considerable level of variations at gene loci controlling vernalization and cold tolerance in dryland wheat genotypes. Data provided here may be used for producing new wheat cultivars adapted to the target environments.

The effect of supplementary irrigation on mycorrhizal symbiosis of Triticum aestivum L. cv.Azar-2 at variable end season rain interruption (spring), was assessed by a 2-year factorial experiment based on randomized complete block design in three replications at West Azarbaijan Agricultural and Natural Resources Research Center in two years (2014 and 2015). Treatments included rain interrupted (30 May, 13 June and 27 June), mycorrhizal symbiosis (non-mycorrhizal plants and inoculation with G.intraradices) and irrigation (rainfed and one supplementary irrigation). Results indicated that the supplementary irrigation increased forage quality (phosphorus and calcium) and grain nutrients (phosphorus) of wheat in comparison with rainfed condition. The highest seed protein content (22%) and seed yield (1327 kg/ha) was observed in irrigated mycorrhizal plants with precipitation interrupted on 30 May and 27 June, respectively. Generally in rainfed, forage and grain quality was improved by supplementary irrigation regardless interrupted precipitation. However, mycorrhizal symbiosis enhanced the wheat quality and yield (15% in supplementary irrigation and 10% in rainfed). It can be concluded that under drought conditions, appropriate water resources management and biofertilizers application would result in better water use efficiency and plants growth, and biofortification as well as sustainable agriculture.

In order to evaluation and screening of drought tolerant sunflower inbred lines, an experiment was conducted in randomized complete block design (RCBD) with six replications at Khoy agriculture and natural resources station during 2014 and 2015. Twenty sunflower lines were evaluated in favored and limited irrigation conditions. Drought stress was imposed by water withholding in R4-R6 stages. The result showed that drought stress reduced plant height and stem diameter, seed weight, head diameter, growth duration and grain yield. Significant differences were observed among lines for these traits. Mean comparison showed that the highest seed yield was belonged to RGK55, BGK375 and BGK1 in non-stressed; and BGK1 and BGK375 in stressed conditions. For evaluation of drought stress tolerance indices such as mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), tolerance index (TOL), stress sensitivity index (SSI), harmonic mean of productivity (HARM), yield stability index (YSI), sensitive drought index (SDI), stress susceptibility percentage index (SSPI), relative drought index (RDI), modified stress tolerance index in optimum irrigation (K1STI), modified stress tolerance index in moderate and severe stress (K2STI) were used.According to these indices and simple correlation, STI, MP, GMP and HARM were the most suitable indices for selection of genotypes under stress and non-stress conditions. Based on the results, BGK1 and BGK375 were determined as the most drought tolerant lines where as RGK23 and RGK26 had the lowest yield and most sensitive to drought stress.