Endosperm Type, Inbred Background, and Leakage of Seed Electrolytes During Imbibition in Sweet Corn

Abstract

Endosperm mutants of maize often exhibit poor seed quality, as indicated by poor germination and seedling vigor. The measurement of seed leachate electrolyte conductivity (SLEC) is a rapid method of evaluating seed quality. Generally, high SLEC indicates poor seed quality. Other endosperm types in addition to sugary (su) are becoming important in the sweet corn industry. To facilitate the conversion of inbreds to new endosperm types and maintain acceptable levels of seed quality, it would be useful to determine the relationship between endosperm type and SLEC. The objective of this study was to determine the effects of inbred background, endosperm type, and inbred × endosperm interactions on SLEC and to determine the relationship between seed weight and SLEC. Ten seed weight and SLEC of six near-isogenic lines differing for 10 endosperm types were measured. Ten combinations of the following endosperms were used; sugary (su), waxy (wx), sugary-2 (su2), dull (du), and shrunken-2 (sh2). Significant differences in SLEC were found among endosperm types: sh2 had the highest SLEC (186.1 dS·m−1) and Su su2 the lowest (62.9 dS·m−1). Over endosperm types, 10-seed weight and SLEC were negatively correlated (r = 0.84**). This negative relationship may be due to damage suffered by the pericarp during the collapse of the endosperm of the lighter endosperm types. Significant differences in SLEC also were found among inbreds. Values ranged from 162.3 dS·m−1 to 55.7 dS·m−1. Among inbreds, SLEC and 10-seed weight was positively correlated (r = 0.82*). Endosperm by inbred interactions had significant effects on SLEC. This interaction is of importance to those converting inbreds to different endosperm types and should be considered when choosing seed parents for hybrid production.

Duration of Imbibition Affects Seed Leachate Conductivity in Sweet Corn

“…All main effects and interactions on SLC were significant. The significance of inbred and endosperm main effects and interactions of these effects were expected (Schmidt and Tracy, 1988). The effect of length of imbi bition on SLC has been reported for soybean (Duke et al 1986) and in three sweetcorn hybrids (Wann, 1986).…”

“…However, cold tests alone are not considered reliable predictors of field emergence (Navratil and Burris, 1980). Seed leachate conductivity (SLC) has been eval uated as a possible method of predicting seedling vigor in maize (Schmidt and Tracy, 1988;Wann, 1986;Waters and Blanchette, 1983). Seed leachate is comprised primarily of potassium, phosphate, sugars, amino acids, proteins, and various other electrolytes (McKersie and Stinson, 1980).…”

“…Wann (1986) found Tochief' had high ger mination percentage and low conductivity, while 'Florida Staysweet' had low germi nation percentage and high conductivity. Schmidt and Tracy (1988) showed that en dosperm genotype shrunken-2 (sh2) had sig nificantly greater SLC than did nine other endosperm types. Generally, sh2 kernels have poor seed quality as measured by germina tion and seedling vigor (Wann, 1986;Waters and Blanchette, 1983).…”

“…The endosperm sh2 has been shown to have higher SLC than does standard su endosperm (Schmidt and Tracy, 1988;Styer and Cantliffe, 1983;Wann, 1986). The sh2 geno types imbibe water more quickly than do their near-isogenic su counterparts (Styer and Cantliffe, 1983).…”

“…It is not known whether high SLC is due to mem brane injury per se during seed processing, permitting the leakage of electrolytes during imbibition or to a higher level of soluble ma terial normally present in the sh2 kernels compared to su kernels. Inbred background was also shown to affect SLC readings (Schmidt and Tracy, 1988).…”