Seed Production in Leafless and Conventional Phenotypes of Pisum sativum L. in Relation to Water Availability Within a Controlled Environment

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Abstract
Water requirements in relation to seed production was studied in near-isogenic lines of leafless (afafstst) and conventional (++++) pea plants (Pisum sativum). The plants were grown to seed maturity in pots in a controlled environment under conditions of high, medium and low irrigation levels. When each genotype was irrigated independently and on demand and the soil moisture content maintained at 65–80 per cent of full capacity there was no significant phenotypic difference in water use efficiency (WUE), defined as g d. wt seed per kg H2O utilized. There existed genotypically-controlled upper and lower limits to yield between which the total dry weight of seed per plant can be determined by water availability. There was no significant differential effect of genotype or of irrigation treatment on the number of pods, number of seed, unit seed dry weight and biological yield per plant. There was significant interaction on stem length, and leaf area at specified nodes. When the water actually required in relation to the water available was taken into account, the leafless phenotype consistently utilized 33–38 per cent less water and produced a correspondingly lower total dry weight of seed than the conventional counterpart. Independently of regime the total dry weight seed per phenotype remained a near constant proportion of the above-ground biomass.