determination of yield and yield components response of soybean (glycin max l.) to swing date, temperature and sunshine hours

this research was done to study the effect of swing date, temperature, and sunshine hours on the yield and yield components of soybean in aliabad katool area (golestan provience), iran in 2012 year. in order to this purpose different soybean fields with different swing date had been remarked in vast area of soybean fields of katool aliabad area. entirely, in this study 30 soybean fields of katool (d.p.x) cultivar and 30 soybean fields of sari (j.k) cultivar had been chosen. to assessment of the studied traits (the length of different phonological periods, yield, and yield components) into each of field, 5 plots in zigzag pattern (∑) had been chosen and in each field, the studied traits had been measured and the average of them was recorded for each field. results showed that sowing date affected on all traits of two cultivars except trait of number of pod per square meter in sari cultivar and reduced significantly. between the trait of seed yield and delay of sowing date (days from 20th june) were a significant relationship and 79 and 53 percentage of the variation in the katool and sari cultivars justified, respectively. according to the slope of the regression equation indicates that delay of sowing date (days from 20th june) reduced seed yield in katool and sari cultivars equal to 50.61 kg.ha-1 and 37.48 kg.ha-1 per day, respectively. relationship of the delay of sowing date (days from 20th june) and different durations of growth (vegetative growth duration, reproductive growth duration and total growth duration) was negative significant at the 0.01 level of significance. also, traits of soybean yield components were affected by average temperature and summation of sunshine hours during flowering and grain filling and increased.