the effect of different sowing dates on physiological characteristics of faba bean (vicia faba l.) varieties in khouzestan ramin

introduction determining the proper time for planting under different climate depends on the factors such as rainfall, temperature and length of day which are the most important aspects of crop production. its importance is because of the severity of these effects on different genotypes to achieve potential production. because different genotypes respond differently to planting delays. sowing date usually interacts with other agricultural management. the goal of this study is to find the perfect time to plant so that environmental factors occurring be favorable for germination, seedling establishment and maintenance of the plant and as far as possible, the plant is faced with a decent condition at any stage of growth. in general, higher growth and higher performance is linked to early sowing date.appropriate integration of crops and varieties are desirable in order to achieve maximum performance. in general, due to the potential capacity for bean cultivation in the khuzestan region and lack of adequate information concerning the proper sowing date in the area, this research focuses on the effect of delayed sowing dates on physiological features of bean cultivars (vicia faba l.) in khuzestan. materials and methods the experiment was conducted in 2013-2014 at the research center of agriculture and natural resources university of ramin in khuzestan. the region located on 31 degrees 36 minutes north and 48 degrees 53 minutes east, and with a height of 20 meters above sea level and is considered as arid and semi-arid areas. the average rainfall is 169 mm. the experiment was conducted as split-plot arrangement based on randomized complete block design with four replications. treatments included five sowing dates as the main factor (october 10, october 25, november 10, november 25 and december 10) and two faba bean varieties (hystal and saraziry) was considered as sub plots. to determine the functional components, 10 plants were randomly marked out of each plot and yield components including grains per pod, number of pods per plant and hundred grain weight were measured. results and discussion the results showed that all features apart from the number of grain per pod were significantly influenced by sowing dates. also, the two varieties showed significant differences in terms of the number of grain per pod, number of pods per plant, grain weight and grain nitrogen. significant differences were found through the interaction of treatments for the features of grain yield, cell membrane stability and chlorophyll-b. the highest grain yield was obtained by second and third sowing date, with an average of 3979.3 and 3849.4 kg per hectare respectively, and the lowest yield was shown at the fifth planting date (1806.2 kg per hectare). conclusions it can be deduced from the results that the sowing dates october 25 and december 10 seem more productive in features like grain weight, number of pods per plant, grain yield and chlorophyll due to the better adaption to climate conditions. meanwhile, late sowing date caused to decrease the number of pods per plant, grain weight, grain yield, relative water content, cell membrane stability and chlorophyll. comparing different types of bean revealed that hystal cultivar had better yield with the highest number of grain per pod, grain weight, and a grain per yield of 4345.7 kg/ha. in general, present study showed that the best planting date is november 10 for hystal cultivar, and october 25 for saraziry.