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 various factors affecting the plant, including water supply, the effect of which has not been fully characterized. The effects of different periods of water stress during reproductive stages on the seed yield and seed physiological quality were investigated in field studies for 3 yr (1991, 1992, and 1993) at Brain-sur-l'Authion, France, on a Mollisol, Rendoll, eutrochreptic soil. Irrigation during seed filling (IDSF) and irrigation during the period from the start of flowering to the start of seed filling were compared with a non-irrigated (NI) and a season-long, irrigated-as-needed (WI) treatment. The physiological quality of pea seeds was assessed by germination percentage and the conductivity and cold tests. The germination percentage averaged 98% and was not modified by water stress. In 1993, rainfall during the reproductive stages was high, and there were no differences in seed yield or quality between treatments. In 1991 and 1992, the rainfall was much lower, and the NI treatment showed the lowest seed yield and quality as far as the conductivity test and cold test were concerned. The WI treatment showed the best yields. Water stress during the flowering period did not reduce seed quality more than WI, and reduced seed yield only slightly. Water stress during seed filling decreased seed yield but the effect on seed quality was not significant. Individual seed weight was higher and less variable in IDSF treatments than in WI treatments. Changing irrigation strategies for pea seed production by irrigating during seed filling may improve the physiological quality of the seedlots without decreasing the seed yield.