Search Results
Abstract
Two degenerative sweet corn mutants, C30, a mutant of P39, ‘Pee Wee’ a mutant of C30 and P39 were crossed with sweet corn inbred C15 to determine their relative abilities to promote heterosis in hybrids. Of the 3 inbreds, C30 had the greatest ability to promote heterosis when in combination with C l5; ‘Pee Wee’ was least effective. Evidently, not all degenerative mutants are capable of promoting marked heterotic effects.
Abstract
A novel procedure was used to test for single locus heterosis in a substantially isogenic background in corn, (Zea mays L.). It was determined that the rd gene and its rd Pw allele do not contribute to single locus heterosis for plant height. To explain why C30 induces heterosis in F1 hybrids, while ‘Pee Wee’ is relatively impotent, a hypothesis is proposed to the effect that C30 evolved from P39 by the addition of a mutagenic and heterotic duplicated chromosomal segment when Rd mutated to rd. In turn, ‘Pee Wee’ developed with the loss of the segment at the time rd mutated to rd Pw.
Abstract
Two degenerative sweet corn mutants, C30, a mutant of P39, ‘Pee Wee’ a mutant of C30 and P39 were crossed with each other and with 4 unrelated inbreds to ascertain their relative abilities to promote heterosis in hybrids. In these tests C30 often exceeded P39 in the promotion of hybrid vigor but ‘Pee Wee’ was relatively inefficient in stimulating heterotic effects.
Abstract
Plants of sweet corn from germinated seeds treated at sub-lethal temperatures were less vigorous and shorter than their controls. The pollen shedding patterns of plants from normal Cl3, T-sterile Cl3 and restored-sterile sweet corn inbreds were not altered by the heat treatments. Pollen shedding patterns among several commercial sweet and field corn hybrids were also unaffected by the treatments. If a virus is responsible for cytoplasmic male sterility in corn it appears to be less sensitive to heat treatment than do the seedlings.
Abstract
Variation within a particular species has resulted in the development of large numbers of cultivars in important horticultural and agronomic crops. A great number of characters are important in the determination of the merit of any cultivar. Variation among characters relating to plant nutrition have not been as well studied as some other characters. Nevertheless, sizeable reviews on this topic have been prepared by Millikan (4) and Vose (5). Stem lesions (Fig. 1) resulting from excess ammonium have recently been described (2, 3). Differences in varietal susceptibility were indicated. The purpose of this investigation was to ascertain if further varietal differences among commercial and experimental lines could be demonstrated.
Abstract
Tomato plants develop dark, pitted stem lesions when grown on ammonium nutrition in soil culture with insufficient potassium, (1,4,5). Ammonium utilization by plants requires a higher potassium level than nitrate utilization (10). Furthermore, when ammonium salt solutions are applied to soils, potassium may be fixed in the clay lattices by ammonium ions (2). Hence, the potassium supplying power of the soil is lowered, and plants are unable to obtain enough potassium to meet their needs. In sand culture, stem lesions occur only when potassium salts are excluded from the nutrient solution with ammonium as the sole nitrogen source (1). Lesions do not develop during potassium deficiency with nitrate sources of nitrogen.