SOURCE-SINK RELATIONSHIP IN BEANS. l. LEAF REMOVAL EFFECT ON YIELD CHARACTERS

Abstract

The leaves are the main supply of photosynthates and constitute the source. Source size (leaf area) might be a limiting factor for seed yield in the common bean. The objective of the present research was to evaluate the effect of leaf removal on yield and its components in common beans. In this regard, greenhouse (I) and field (II) experiments were conducted at Iguala, Gro. (1986) and Chapingo, Méx. (1987) respectively, using Michoacán 12-A-3, an indeterminate bush bean cultivar. Leaflet removal treatments were given at the begining of the flowering stage and in the experiment I consisted of the removal of either 1 or 2 of the lateral leaflets
(33% and 66% of the leaf area) or all the leaflets from leaves located in the lower, middle and upper stratum of the plant. In the experiment II, treatments consisted of the removal of 66% of the leaf area in the first or second half of the flowering period. In both experiments, intact plants were used as controls. The removal of 66% and of all the leaves from either upper, middle or lower stratum significantly decreased seed yield per plant in comparison to the control and the removal of 33% of the leaf lamina.
The removal of 66% of the leaf area in the first o second half of the flowering period, significantly decreased pod number, seed number and seed yield. Removal of all the leaf lamina decreased seed yield by 95%, suggesting that petioles, stem and pericarps, might supply some photosynthates for seed yield.