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Physiological, Morphological, and Agronomic Responses of Two Groundnut (Arachis hypogaea L.) Genotypes to Drought During the Reproductive Stage
Dissertation Abstract:
Two experiments were conducted at the experiment station of the University of the Philippines Los Baños during the dry season of 2004 and 2005 to study the effect of drought of varying duration imposed at different reproductive phases on yield and yield components, dry matter partitioning, and root distribution of two groundnut genotypes (Biyaya 10 - Spanish type and CLSU super peanut - Virginia bunchy type) differing in canopy structure and maturity under field and greenhouse conditions.
In the field, the pod yield of Biyaya 10 was significantly affected only when drought was imposed for 20 days regardless of reproductive phase whereas CLSU super peanut did not show significant differences across drought durations. Regardless of genotype, the 10-day drought during pegging and pod filling phases significantly decreased pod yield whereas the differences associated with reproductive phase when drought was imposed 15 and 20 days were insignificant. In the greenhouse, Biyaya 10 had significantly lower pod yield when drought was imposed during the pod filling phase for 15 and 25 days. CLSU super peanut showed different response--that is, pod yield was significantly lower when drought was imposed for 15 days during the pod filling phase than during the flowering phase and also significantly lower when drought was imposed during the flowering phase for 25 days. Harvest index and number of pods per plant were significantly affected by two- and three-factor interactions both under field and greenhouse conditions. Significant differences in various dry matter partitioning indices like leaf weight ratio, stem weight ratio, root weight ratio, peg weight ratio, pod weight ratio, and root biomass distribution with soil depth were attributed to various two-factor interactions under greenhouse conditions. Further studies are needed to confirm genotypic differences in terms of preferential partitioning of dry matter and remobilization of assimilates stored in the stem under drought during the reproductive stage. Plant characters that are directly contributing to pod yield under drought during the reproductive stage should also be identified.