Physiological Impacts Caused by Gamma Irradiation and Different Sowing Dates and Their Effects on Yield of Snap Bean

摘要

Seeds of snap beans (Phaseoulus vulgaris. L) cv. Paulista were irradiated with 0, 20 or 30 Gy ofgamma radiation in seasons 2011 and 2012 prior to sowing using caesium as a radiation source. Early wintersowing dates investigated in this trial were 1st, 8th and 15th of October. The experiment was laid out in a factorialarrangement of three replicates in a randomized complete block design where snap bean seeds were sown 5 cmapart on the top of 60 cm wide rows in the experimental field of NCRRT, Nasr City, Cairo, Egypt. Concentrationsof chlorophyll, carbohydrates, total soluble phenols and proline were determined in the fourth expanded upperleaf, 45 days after sowing while the concentrations of gibberellins, auxins and abscisic acid were recorded30 days after sowing. Shoot fresh weight and dry weight were also determined 45 days after planting. At harvesttime, pods were harvested at maturity stage, total sugars and total proteins were determined and different yieldcomponents where recoded. Delayed sowing generally resulted in increased chlorophyll, total soluble phenolsand proline and reduced carbohydrates, gibberellins and auxins in leaves and among the sowing datesinvestigated, Oct. 8th was superior in regards of local exportable and total yield. On the other hand, investigatedirradiation doses generally increased carbohydrates, total soluble phenols and proline and endogenousgibberellins and auxins in leaves. It also increased total pod sugars and proteins. Moreover, the 20 Gy doseproved to be useful in regards of local, exportable and total yield.