Effects of soil moisture stress on floral and pods abortion, reproductive efficiency and grain yield in soybean genotypes (Glycine max (L) Merrill)

Abstract

Experiments were conducted at Ilorin, Nigeria to evaluate the effects of soil moisture stress at different growth stages (vegetative, flowering and pod filling) on floral and pods abortion, reproductive efficiency and grain yields of ten soybean genotypes (TGX 923-2E, TGX 1440-1E, Samsoy- 2, TGX 536 02D, TGX 1019-2E, TGX 1448-2E, TGX 1844-18E, TGX 1830-2DE, TGX 1740-2F and TGX 1817-12E). A regularly watered (control) treatment was included in all the replicates. There were significant variations (p < 0.001) in flower and pods abortions, yield components and grain yields of the genotypes, as well as in the moisture stress treatments. Reproductive efficiency was, however, not significantly affected by any of the two factors. Grain yield was highest with TGX 1844-18E due to high number of flowers and pods produced. Similarly moderate floral and pods abortions, as well as high pod and biomass yields were recorded in the variety. Grain yield was lowest in TGX 1817-12E resulting from lower number of flowers and pods produced, high floral and pods abortions and low pod and biomass yields. Soil moisture stress, especially when it occurred at the vegetative and flowering stages significantly reduced flower and pods production, biomass yield, and slightly increased floral and pods abortions. Conclusively, reductions in grain yields as a result of moisture stress at any growth stage was due to reduction in sink sites where dry matter is to be stored. This occurs because of reduction in the ability to translocate more photosynthates to the sites during pod filling. Results of this study showed Samsoy-2 and TGX 1817-12EN to be the most tolerant genotypes to soil moisture stress, while TGX 1019-2EN and TGX 536-02D, the least tolerant.

Keywords: Floral and pod abortion; reproductive efficiency; soybean genotype; moisture stress

Moor Journal of Agricultural Research Vol. 7 (1&2) 2006 pp. 9-14