Kernel quality, germination rate and seedling performance of eight wheat varieties produced under three different irrigation regimes

The effects of three different irrigation treatments were tested on kernel quality (i.e. kernel size), germination rate and seedling performance of eight wheat varieties. The irrigation treatments used were as follows: (i) rainfed treatment with 262.8mm annual rainfall received during the growing season, (ii) partial irrigation (PSI) treatment receiving 482.8 mm of water (262.8mm rainfall + 220mm irrigation at anthesis) and (iii) continuous supplementary irrigation (CSI) receiving 640 mm water (262.8 mm rainfall + 377.2 mm supplementary irrigation at 2-3 weeks interval). Seven durum wheat varieties (Sham1, Omqais, Acsad65, Bani Suef6, Bani Suef4, Horani Nawawi, Dairalla6) and one bread wheat variety (Ammon) were included in this study. Split-plot design was used with three replications. The main plots were the irrigation treatments, while the sub-plots were varieties nested within irrigation treatments. Kernels weight was recorded under different irrigation treatments in addition to the germination rate parameters (mean germination time and the time to attain 10% and 50% of complete germination percentage) and seedling attributes (shoot length, maximum seminal root length, coleoptile length, shoot fresh weight and seminal root fresh weight). The thousand kernel weight (TKW) was maximum under PSI (46.21g), followed by CSI (43.20g) and rainfed treatment (41.70g). TKW was maximum in Cham1 (45.37g) and BaniSuef6 (45.22g), while the minimum TKW was recorded in Ammon bread wheat variety (39.19g). Smaller wheat kernels released under rainfed condition were notoriously faster to germinate as compared with kernels released under CSI and PSI, and consequently smaller kernels would be desirable to accelerate the time required from sowing to seedling emergence. Hourani Nawawi and DairAlla 6 gave a more vigorous seedling with longer seminal roots and larger seedling biomass, which might indicate their high adaptability to early drought. In conclusion, smaller kernels were faster in germination, which minimize the time required from germination to emergence for a good stand establishment, while heavy kernels would have seedlings with a more vigorous root system which may help the crop to withstand early drought