Reproductive response of two morphologically different pea cultivars to drought

Water use by semi-leafless peas (Pisum sativum L.) is usually less than that of conventional peas because of their reduced surface leaf area, suggesting that semi-leafless peas would be less sensitive to drought because drought develops later. This work aimed to study the reproductive response of peas cv. Solara (semi-leafless) and cv. Frilene (conventional) subjected to similar controlled soil drought during the critical period occurring between flowering and initial seed filling. Plants were subjected to drought by watering with a fraction of water used in the evapotranspiration of control plants. Soil, pod and seed water contents, leaf water status parameters, dry matter (DM) partitioning, seed yield, yield components and water use efficiency (WUE) were measured. Although soil water content decreased in a similar way in both cultivars, leaf Psi(w) and RWC only decreased significantly in Solara. Well-watered Frilene plants produced higher shoot and pod DM, but lower seed DM. Well-watered Solara plants produced lower pod DM and higher seed DM than Frilene. Under drought, Frilene increased partitioning of total plant DM to vegetative organs, particularly roots, and decreased DM allocation to pods and seeds increasing flower abortion. By contrast, droughted Solara interrupted vegetative growth and increased leaf senescence but maintained similar partitioning of total plant DM to pods and seeds as in well-watered conditions. For both cultivars there was a close relationship between the percentage of total DM partitioned into seeds and WUE, (water use efficiency on seed yield basis). Results demonstrate that when plants suffered 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 Science B.V. All rights reserved.