Effects of water stress applied at different phenological phases on yield components of dwarf bean (Phaseolus vulgaris L.)

Abstract

Drought treatments were applied to seven sets of dwarf bean plants in pots. Each was subjected to water stress during one of the seven phenological phases, ranging from bud stage to grain filling. Treatments consisted of withhold- ing irrigation until 80 % of the available water capacity was used. Evidence of differential effects of water stress accord- ing to the phase of application was obtained by tagging all the floral organs (buds or pods) present during the phase. Fallen tags indicated how many organs had aborted before physiological maturity. Periods of flowering (pl: bud, p2: flower opening, p3: fruiting set) were more sensitive than pod elongation (p4 and p5) and grain filling (p6 and p7) phases. Bud abortion rate was 50 % in non-stressed plants and 70 % in stressed ones. The final pod number was 53 % lower in plants stressed during the p1 period (the most sensitive period) than in controls. Pod number was generally much more sensitive to drought than the seed number per pod, which was only 13 % lower than in controls for plants stressed dur- ing the p1 period. ( © Inra/Elsevier, Paris.) Phaseolus vulgaris / yield component / water stress / phenological phase Rsum -Effet d'un stress hydrique appliqu diffrentes phases phnologiques sur les composantes du rende- ment du haricot nain (Phaseolus vulgaris L.). Nos essais ont pour but d'tudier l'effet d'un stress hydrique de mme intensit appliqu diffrentes phases phnologiques de la priode de reproduction, sur les composantes du rendement exprimes en nombre, du haricot nain (Phaseolus vulgaris L, varit Coco de Prague). Afin d'viter le phnomne de chevauchement des diffrents organes fructifres, la priode de reproduction est divise en sept phases phnologiques, de la phase bouton floral la phase de fin remplissage des gousses. Chaque phase subit une seule fois le stress durant tout le cycle vgtatif. Ce stress correspond un dficit de consommation en eau gal un taux de tarissement en eau du sol en fin de stress de 80 % de la rserve utile (RU). Le marquage systmatique de la priode laquelle les organes