Effect of environmental conditions on productivty and seed quality of soybean

Two field experiments were conducted at the Agricultural Experiments and Researches Station, Faculty of Agriculture, Cairo University, Giza, Egypt during 2009 and 2010 seasons. The objectives of this study were to investigate the response of some recen local soybean cultivars to seasonal changes, cropping systems and seeding rates and the effects of these factors on soybean growth, grain yield and its components. Two cropping systems, as solid soybean and intercropping of 4 soybean ridges alternate with 2 corn ridges, were adopted. Giza 21, Giza 35 and Giza 111 soybean Egyptian cultivars were used. The seeding rates were 210 000, 175 000 and 140 000 seeds/ per Feddan (Fed =4200 m²). Out of the studied soybean yield and yield component traits, 7 traits were significantly affected by seasonal (S) variations. Air temperature and relative humidity (RH) during the growing periods indicated that the 2010 season was characterized by higher temperatures and RH. Cropping systems (CS) significantly affected soybean plant height (PIHt), seed yield / plant (SY/P) and harvest index (HI). However, the (S x CS) interaction was insignificant for all traits. Seeding rates (PD) significantly affected seed yield / plot (SY /plot) and seed index (SI). The interaction of PD with other studied factors, recorded significant variances due to CS x PD interaction for days to flowering onset (DF) and seed index (SI). Mean squares due to soybean cultivars varied significantly for DF, days to maturity (DMAT), HI, and SI. Such cultivars performed differently from season to another for DF, DMAT, pods and seed yield /plant (SY/P). The studied soybean cultivars varied for stability in performance only for environmentally highly and moderately affected traits. It may be concluded that performance of soybean traits is differently influenced by the environmental conditions and could be classified in this respect to sensitive, moderate and tolerant to environmental conditions. This variation in performance of soybean traits should be taken into considerations in soybean yield trials in attempting to improve the level of stability of soybeans. Seasons (S) is a significant (or highly) source of variation for all studied soybean traits, except days to flowering onset (DF), branches / plant and seed index (SI). Seasonal (unpredictable effects) plus cultural practices changes (predictable environmental effects) greatly affected the soybean traits. However, genotypic differences were significant for DF, HI and SI.