Search Results
Abstract
Seed leachate conductivity (SLC) has been evaluated as a possible method of measuring seedling vigor in sweet corn (Zea mays L.) and other crops. It is known that genotypes leak solutes at different rates. Thus, it is important to determine if the different rates of leakage result in different SLC determinations when SLC is measured after various lengths of imbibition. A study was conducted using near-isogenic lines of three inbreds (C68, P39M94, and Ia5125a) in combination with five endosperm types, sugary dull (su du), sugary sugary-2 (su su2), sugary dull waxy (su du wx), shrunken-2 (sh2), and sugary (su), to evaluate the effect of length of imbibition and the interaction of imbibition length and endosperm type and inbred background on conductivity. Readings were taken at 0, 2, 4, 6, 8, 10, 12, 14, and 24 hr after the start of imbibition. Conductivity was affected by length of imbibition, inbred background, and endosperm-type main effects and interactions of these effects. Conductivity increased with increasing time after imbibition. Ranking of endosperm types within each inbred was stable by 2 hr after imbibition, although differences were not always significant. Thus, the interaction effects were due to an increasing separation over time and not to a change in ranking of the genotypes. However, means separation was greatest at 24 hr after imbibition.
Abstract
The thickness of the pericarp is one of the most important factors determining quality in sweet corn (Zea mays L). A study was conducted to determine if differences observed in pericarp thickness between kernels with starchy sugary-2 (Su su2) and sugary sugary-2 (su su2) endosperm types were due to linkage effects or endosperm genotype effects. Reciprocal crosses were made between near-isogenic lines with Su su2 and su su2 endosperm types in four inbred backgrounds. The F1 plants were self-pollinated and ears segregating at the sugary locus were analyzed for pericarp thickness. The pericarp is maternal tissue, therefore all kernels from an ear have the same genotype regardless of the endosperm genotype. Highly significant effects (p ≤ 0.01) for pericarp thickness were found for endosperm, inbred, and endosperm by inbred interactions. If differences between Su su2 and su su2 endosperms were due to linkage effects, endosperm type would not have been significant. Endosperm type Su su2 had thicker pericarp than su su2 in all inbred backgrounds, but differences were significant in only two of the four backgrounds. Averaged over four inbred backgrounds, the pericarp thickness of Su su2 kernels and of su su2 kernels was 45 and 35 µm, respectively. A difference of this magnitude might be detectable as a difference in sweet corn tenderness.
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.