Reproductive response of two morphologically different pea cultivars to drought

Water use by semi-leafless peas (Pisum sativum L.) is usually less than tha t of conventional peas because of their reduced surface leaf area, suggesti ng that semi-leafless peas would be less sensitive to drought because droug ht develops later. This work aimed to study the reproductive response of pe as cv. Solara (semi-leafless) and cv. Frilene (conventional) subjected to s imilar controlled soil drought during the critical period occurring between flowering and initial seed filling. Plants were subjected to drought by wa tering with a fraction of water used in the evapotranspiration of control p lants. Soil, pod and seed water contents, leaf water status parameters, dry matter (DM) partitioning, seed yield, yield components and water use effic iency (WUE) were measured. Although soil water content decreased in a simil ar way in both cultivars, leaf Psi(w) and RWC only decreased significantly in Solara. Well-watered Frilene plants produced higher shoot and pod DM, bu t lower seed DM. Well-watered Solara plants produced lower pod DM and highe r seed DM than Frilene. Under drought, Frilene increased partitioning of to tal plant DM to vegetative organs, particularly roots, and decreased DM all ocation to pods and seeds increasing flower abortion. By contrast, droughte d Solara interrupted vegetative growth and increased leaf senescence but ma intained similar partitioning of total plant DM to pods and seeds as in wel l-watered conditions. For both cultivars there was a close relationship bet ween the percentage of total DM partitioned into seeds and WUE, (water use efficiency on seed yield basis). Results demonstrate that when plants suffe red the same level of drought in the soil, the reproductive response of the two cultivars was linked to differences in their WUE. (C) 1999 Elsevier Sc ience B.V. All rights reserved.