Studies of the Physiological Basis for Yield Differences. II. Variations in Dry Matter Distribution Among Aerial Organs for Several Dry Bean Varieties1

Abstract

The extent of variation in distribution of accumulated dry matter among aerial organs at maturity was compared for 11 varieties of Phaseolus vulgaris L., representing marrow, red kidney, yelloweye, and pea types of dry bean. The lowest percentages of aerial dry weight present as fruit (seed and pod wall) were exhibited by the red kidney and pea bean varieties. ‘Charlottetown’ yelloweye exhibited the highest percentage as fruit and the highest harvest index (percentage of aerial dry weight as seed), but it had the lowest seed yield because of early maturity and accompanying low dry matter accumulation. The second highest harvest index was exhibited by ‘Cornell 7–16’ which regularly out‐yielded all other varieties. Harvest indices of the varieties varied from 53% to 67%. The high seed yield and harvest index of 7–16 were accompanied by the highest ratio for seed weight divided by pod wall weight. Harvest index was not correlated with time to maturity nor with determinate and indeterminate growth habits. In addition to harvest indices the varietal expressions of leaf‐area, leaf‐area ratio, relative growth rate, relative leaf growth rate, and net assimilation rate are discussed. This information on genetic variability and the inter‐relationships of these many factors provides improved understanding of the physiology of yield differences in beans. It also provides a physiological basis for formulating a program of breeding higher yielding dry bean varieties.