CARBOHYDRATE AND PROTEIN ACCUMULATION IN THE DEVELOPING FIELD PEA SEED

Abstract

Changes in quality factors during seed maturation were examined in yellow smooth-seeded field peas (Pisum sativum L. ’Trapper’) under different nitrogen (N) regimes. Sucrose was the sole oligosaccharide (17% of dry weight) at 15 days post-anthesis, but at full seed maturity (80 days post-anthesis) had decreased to 2.2% of seed dry weight. At maturity, raffinose, stachyose, and verbascose content had reached concentrations of 0.6, 1.8, and 2.3%, respectively. Total oligosaccharide content remained constant regardless of variation in seed protein concentration, and was unaffected by applications of N fertilizer. Seed protein (%) was found to be variable and positively correlated with N fertilizer treatments. Seed protein (dry basis) decreased during seed maturation. This decrease was most evident in the absence of added N fertilizer. Symbiotic fixation (acetylene reduction) was low in all treatments and made little contribution to plant N content. Fixation in the absence of added N was insufficient to maintain seed N at levels comparable to those observed in the high-N fertilizer treatments. The constancy of oligosaccharide content under the different fertilizer regimes indicated that the content of these components might be more amenable to genetic manipulation via selection rather than by varying management practices.