فصلنامه علوم زراعی ایران
سال بیستم شماره 4 (پیاپی 80، زمستان 1397)

To evaluate nitrogen use efficiency in intercropping replacement ratios of maize and bean, an experiment was conducted during two successive cropping years of 2014-2015 and 2015-2016 at Agricultural Research Station, Ferdowsi University of Mashhad, Mashhad, Iran. Experimental factors were arranged as split plots in randomized complete block design with three replications. The main plots consisted of sole culture of maize and bean, row intercropping with ratios of 50%:50%, 67%:33% (2 rows of maize: 1 row of bean) and 33%: 67% (1 row of maize: 2 rows of bean). Application and no-application of nitrogen (N) fertilizer (55 kg.ha-1) were assigned to sub plots. The results showed that different ratios of maize and bean intercroppings and application of nitrogen fertilizer had significant effects on grain yield and biomass as well as nitrogen use efficiency indices (such as uptake, utilization and productivity). Maximum grain yield and biomass of bean (3462.1 and 10124.5 kg.ha-1 respectively) and maize (5974.1 and 18321 kg.ha-1, respectively) were obtained from sole cropping of bean and maize. In both crops, N utilization efficiency was higher in all treatments when nitrogen productivity was calculated using grain yield. In nitrogen application treatment, the row intercropping ratio of 50:50 of bean and maize had higher nitrogen uptake efficiency for both crops. Also, the ratio of planting 1 maize: 1 bean (50% maize: 50% bean) had the highest total land equivalent ratio (1.10) using grain yield, nitrogen uptake efficiency (2.30) and nitrogen productivity efficiency (using grain yield (1.98) and biological yield (2.02)). Therefore, it can be concluded that the use of maize and bean row intercropping is an environmental friendly cfrop management pratctice to reduce nitrogen losses and improve its uptake efficiency, and to prevent the excessive use of chemical fertilizers and improve the productivity of these inputs in agroecosystems.

To estimate gene action and genetic parameters of seed yield and some morphological traits, six variety and lines of chickpea as well as seed derived from their diallel crosses were evaluated in a randomized complete block design with four replications in 2016-17 at Gerizeh research station of Sanandaj, Iran. Significant differences were identified among genotypes for all traits. Genotypic variances were partitioned into additive and non-additive genetic components using Hayman method. Additive genetic component were significant for all traits excluding one-hundred seed weight. Non-additive component was significant for all traits at 1% probability level. The highest and lowest degrees of dominance were observed for plant height and number of seed per pod, respectively. Mean of dominance ratio revealed genes partial dominance for days from sowing to flowering and seeds per pod, and over dominance for other traits. Broad-sense heritability estimates ranged from 0.91 for number of pod per plant to 0.68 for seed weight. Highest and lowest values of narrow-sense heritability were estimated from 0.73 for days to flowering to 0.06 for seed yield, respectively. Graphical analysis of Wr /Vr indicated that there was a complete dominance for days from sowing to flowering, 100 seed weight and seed yield. For days from sowing to maturity, number of seed per pod, intercept was positive, and controlled by partial dominance gene action. On the other hand, for number of pods per plant and plant height, the intercept was negative and the gene action was over dominance. For seed yield, except ILC 482, the parents were close to the origin of the coordinate axis and contained more dominant alleles. It is concluded that crossing cv. Azad with high yield potential cultivars can be more suitable, and for this purpose the parents that were located farther from intercept in Wr /Vr diagram are preferred.

Wild relatives of safflower are considered a useful source of desirable genes to develop improved cultivars for important agronomic and physiologic traits such as drought and salinity tolerance as well as increasing seed yield. Among wild species, cross compatible species are highlighted to obtain high genetic gain in next generations. In the present study, Carthamus tinctorius, C. palaestinus and C. oxyacanthus were crossed with each other and three segregating populations were developed. Single plant selection (SPS) and stress tolerance index (STI) were jointly employed in F4 and F5 generations for these three populations. Genetic gain was obtained under both water stress and non-stress conditions for several traits including seed yield. Genotypes from A and D groups of the three-D plots in F4 generation were repeated exactly in the same groups in the three-D plots of F5 generation indicating a very high selection efficiency. Response to selection in different interspecific populations under water stress and non-stress conditions identified suitable criteria for improving seed yield. High response to selection plus high broad sense heritability for several traits indicated the contribution of genetic variation more than environmental factors. Number of seed per capitulum, capitulum diameter, capitulum weight, 100-seed weight and number of branches had high narrow-sense heritability, and could be suggested as important and key traits for safflower breeding programs in water limited conditions. It is concluded that combining STI with SPS method in safflower interspecific breeding may efficiently identify superior genotypes in the early segregating generations under water stress and non-stress conditions.

Rising temperature as consequences of climate change could affect on the various processes such as photosynthesis, respiration, partitioning of assimilates and ultimately grain yield of agricultural crops. The present experiment was conducted to simulate the impacts of climate change on maize grain yield under two future climate change scenarios (RCP4.5 and RCP8.5) using APSIM model in three counties of Kermanshah province (Kermanshah, Kangavar and Eslamabad Gharb). Future climate data were projected by using long-term climatic data for the baseline period of 1980-2010 and AgMIP methodology for the mid-future (2040-2070). The results showed that, on average, the mean temperature increased up to 11 and 23 percent under RCP4.5 and RCP8.5 scenarios when compared to the baseline, respectively. The maximum and minimum grain yields in the baseline were obtained in Kangavar (14399 kg.ha-1) and Kermanshah (7741 kg.ha-1), respectively. Simulation results also showed that average temperature during growing season rised (0.5 and 2 ˚C under RCP4.5 and RCP8.5, respectively) and length of growing season decreased (5 and 6 percent under RCP4.5 and RCP8.5, respectively) which resulted in a reduction in maize grain yield from 69 to 90 percent under RCP4.5 and RCP8.5, respectively. Results illustrated that under climate change conditions, flowering of maize may coincide with high temperatures and this may reduce maize grain yield, therefore, it can be suggested that changing the sowing dates in the target regions prevents the coincidence of the critical flowering stage with heat stress.

Improvement of rice characteristics of Iranian traditional and high-yielding cultivars is very important in rice breeding programmes for sustainable rice production in Iran. Therefore, a total of seven advanced promising breeding lines of rice were tested for their adaptability and genotype × environment interaction in 2014 to 2016 and four locations at Amol, Babol, Behshahr and Tonekabon, Iran. Results of analysis of variance showed significant differences among these promising breeding lines and their parents as well as check cultivars for important characteristics such as grain yield, plant height, panicle number per plant, grain per panicle most of environments. It's found that promising breeding line G1 (AN74), originated from Alikazemi × Nemat, was significantly early maturity as compared with other lines, and was similar to Tarom-Mahalli, a local variety. Combined analysis of variance indicated that year, year × location, genotypes × location and year × location × genotype interaction effects were significant on grain yield. According to the adaptability analysis for grain yield, we found that two promising breeding lines; AN74 (G1) with bi=0.62 and an average yield of 6500 Kg/ha showed specific adaptation in central Mazandaran, while genotype TS84 (G7) with bi=0.89 and average yield of 8089 kg.ha-1 with higher yield and yield stability in most of the environments. Analysis of genotype × environment interaction through AMMI method showed that two first components of interaction (IPCA1 and IPCA2) were significant explained 36.8 and 26.1 percent of the variation in grain yield, respectively. The promising breeding line AN74, of Ali-Kazemi background, with an average of 97 days to 50 percent flowering, plant height of ~85 cm and intermediate amylose content (20~24 %) was identified as a suitable promising breeding line for centeral areas of Mazandaran. Another suitable promising breeding line with Tarom background, TS84, was well adapted to rice growing areas in Mazandaran. Therefore, these two promising breeding lines; AN74 and TS84 can be considered for further verifications on farmers’ fields for being released as new rice cultivars.

Ten SSR morkers linked to different genes and QTLs responsible for the salinity tolerance in rice, including Saltol QTL which located between zero to 8 CM of the genes, were used to validate their co-segregation with salinity tolerance. Fifty nine diverse rice genotypes including local and improved cultivars mostly from Iran and few exotic rice genotypes were tested during 2009-2011 at Rice Research Institute of Iran, and data were collected on several important traits such as salinity tolerance, seedling height, root dry matter, shoot dry matter and leaf relative water content (RWC). The treatments were: a. control with an electrical conductivity of 0.9 dS.m-1 and b. salinity stress with EC = 12 dS.m-1 for all rice genotypes at seedling stage. Molecular screening for 10 SSR linked marker showed that they amplified 60 alleles among rice genotypes. We identified four SSR markers which significantly co-segregated with at least one trait that was involved in salinity tolerance including; RM315 with seedling height, RM223 with root dry weight and seedling height, RM3627 with root dry weight, seedling height and RWC; and RM8094 with root dry weight and RWC. Molecular data clustering through UPGMA method and Yule coefficient also classified rice genotypes into five major clusters with tolerance to susceptible reactions. As three aforementioned SSR markers; RM315, RM3627 and RM8094 are located on chromosome 1, closely linked to Saltol QTL, and co-segreated with different traits in this experiment, they could be employed to differentiate salinity tolerant rice genotypes in rice breeding programs in Iran.