Leaf Abscission in Varieties ofPhaseolus vulgaris(L. ) andGlycine max(L. ) Merrill/emdash a—Correlation with Propensity to Produce Adventitious Roots

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Abstract
In field trials of Phaseolus vulgaris large differences were observed between varieties in the rate at which the leaves abscised. Similar differences were found in the rate of decline of the chlorophyll content of excised leaf discs. A grafting experiment showed that the differences in leaf abscission depended on the genotype of the scion and on that of the rootstock. Scion and stock effects of each genotype were similar, and additive. Rootstock/scion combinations which conferred enhanced leaf retention produced greater yields of seed and of seed nitrogen. When shoots of delayed-senescence genotypes of P. vulgaris were held in water they produced more adventitious roots than did shoots of rapid-senescence genotypes. This relationship between senescence pattern and adventitious rooting was also observed among varieties of Glycine max, and between isogenic lines of G. max differing in the leaf abscission alleles Ab/ab. These results are discussed in relation to current theories of leaf senescence, abscission, and the production of yield.