Role of Seed Mineral Content in the Occurrence of Transverse Cotyledon Cracking of Snap Bean

Abstract

Abstract Seed calcium, magnesium, and potassium contents of 4 snap bean cultivars (Phaseolus vulgaris L. ‘Spartan Arrow’, ‘Astro’, ‘Avalanche’, and ‘Early Gallatin’) were studied in relation to degree of susceptibility to transverse cotyledon cracking (TVC). TVC index numbers ranged from a minimum of 13 (resistant) to a maximum of 111 (extremely susceptible). To determine whether seed Ca is related causally to TVC, seed Ca content was altered through foliar application of calcium polycarboxylate. Without supplemental Ca sprays, the seed Ca contents of the 4 cultivars varied from 17.3 to 24.7 μ eq/g. Calcium sprays increased seed Ca contents by up to 18%. In some instances, changes in the amounts of seed Ca were as great as the initial varietal differences in seed Ca content. The TVC indices of the cultivars remained unchanged, however, and multiple regression analyses indicated that seed Ca content was not significantly correlated with TVC (R2 = 0.014). In addition, no significant correlations were found between TVC and seed K contents or Ca to Mg ratios. On the other hand, a significant negative correlation occurred between seed Mg contents and degree of TVC (R2 = 0.298). This correlation, however, depended largely upon varietal differences in seed Mg content and may not represent a causal relationship with TVC. Varietal characteristics other than seed mineral content apparently account for differences in susceptibility to TVC.