WATER-STRESS DURING REPRODUCTIVE STAGES AFFECTS SEED QUALITY AND YIELD OF PEA (PISUM-SATIVUM L)

Physiological quality of pea (Pisum sativum L.) seed depends on variou s factors affecting the plant, including water supply, the effect of w hich has not been fully characterized. The effects of different period s of water stress during reproductive stages on the seed yield and see d physiological quality were investigated in field studies for 3 yr (1 991, 1992, and 1993) at Brain-sur-l'Authion, France, on a Mollisol, Re ndoll, eutrochreptic soil. Irrigation during seed filling (IDSF) and i rrigation during the period from the start of flowering to the start o f seed filling were compared with a non-irrigated (NI) and a season-lo ng, irrigated-as-needed (WI) treatment. The physiological quality of p ea seeds was assessed by germination percentage and the conductivity a nd cold tests. The germination percentage averaged 98% and was not mod ified by water stress. In 1993, rainfall during the reproductive stage s was high, and there were no differences in seed yield or quality bet ween treatments. In 1991 and 1992, the rainfall was much lower, and th e NI treatment showed the lowest seed yield and quality as far as the conductivity test and cold test were concerned. The WI treatment showe d the best yields. Water stress during the flowering period did not re duce seed quality more than WI, and reduced seed yield only slightly. Water stress during seed filling decreased seed yield but the effect o n seed quality was not significant. Individual seed weight was higher and less variable in IDSF treatments than in WI treatments. Changing i rrigation strategies for pea seed production by irrigating during seed filling may improve the physiological quality of the seedlots without decreasing the seed yield.