Prediction of growth stages of soybean cultivars and lines using climatologic parameters of photoperiod and temperature in karaj region

Soybean development Reproductive stage were predicted by climatic parameters as daylength and temperature. Therefore، fifteen soybean lines and cultivars as name as Williams، Zane، M4، M12، S. R. F، Miandoab، A3935، A3237، L17، Union، Grangelb، Clark، Tns95، Elf، Calland were studied in four planting dates. Soybean genotipes were used in a RCBD in each planting dates. Daylength and temperature effect were evaluated by planting dates levels. Flowering occurance and development Reproductive stage duration were fitted growth degree days، photoperiod and photothermal units in a Multiple Regression Method. The results indicated that photoperiod had significant effect on Maturity in all of lines and cultivars. But photothermal had positive significant effect in Williams. Therefore It caused to delay in Maturity if It was increased. Photothermal was calculated from growth degree days by photoperiod in each days. But the photoperiod was more effective than gdd in time of Maturity. Growth degree days affected on time of Maturity by photothermal and caused to promote it. Reproductive development duration of Elf was affected by gdd.