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  • Author or Editor: M. L. Weaver x
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Abstract

A study was undertaken to determine a) if genotypic responses for fruit set and pollen viability in tomatoes (Lycopersicon esculentum Mill.) exposed to high temperatures are related, and b) if pollen viability at high temperature could be used to screen tomato plants for better performance in high-temperature environments. Fruit set, pollen germination, and pollen tube length varied among tomato sources exposed to 40C for 60 min, and both pollen germination (r = 0.988***) and pollen tube length (r = 0.815**) correlated positively with fruit set. Differentiation among tomato sources for increased pollen viability at high temperature was accelerated by increasing the temperature at which flowers were exposed from 40 to 48C. Pollen viability has a major role in determining the fruit set of tomatoes at high temperatures and can serve as a basis of screening for tomato plants that will potentially produce higher fruit yield in high-temperature environments.

Open Access

A nonenzymatic technique using dilute salt solutions effected rapid release of viable protoplasts from mature bean (Phaseolus vulgaris L.) pollen. Protoplasm release started within 30 sec and was completed within 5 min in solutions of 0.02 to 0.06 m NaCl, or KCl, pH 6 to 9. The degree of release could be altered by changing the concentrations and ratios of CaCl2 and H3BO3 and by adding sucrose to either solidified or aqueous salt media. The surface of nonenzymatically released protoplasts was partially digested by short-time exposure to a mixture of cell wall-degrading enzymes and then examined by scanning electron microscope.

Free access

Abstract

Viability of pollen grains of isogenic sibling bean (Phaseolus vulgaris L.) selections of known tolerance of sensitivity to high temperatures (HT), as previously determined by pod retention and seed yield, was compared to that of a common parent bean selection and a cowpea [Vigna unguiculata (L.) Walp.] cultivar. Exposure of newly opened flowers to temperatures of 35° or 41°C reduced the viability of pollen grains in all bean selections. Pollen of all sibling selections was less affected by HT than pollen of their common parent suggesting transgressive segregation of factors for HT tolerance. At 41°, most pollen grains were destroyed in the parent bean selection and the 2 HT-sensitive siblings, whereas 44% to 55% of the pollen grains appeared to be viable in the 2 HT-tolerant siblings. Pollen viability of the HT-tolerant cowpea cultivar was not reduced by temperatures to 41°. Pollen staining indicated an interrelationship between pollen viability and tolerance to HT stress among the bean selections. The technique described has the potential for rapid selection of HT-tolerant genotypes in hybrid populations.

Open Access

Abstract

Two bean cultivars and one breeding selection with different pod-retention characteristics were grown at mean soil moisture tension (MSMT) of 0.05 and 0.1 MPa in 2 separate plantings. In the 5 May planting, flower buds developed during the 1st 3½ weeks of flowering, were dated and counted, and those developing mature pods were identified. Sixty-five percent to 90% of all pods that reached full maturity were from floral buds that reached anthesis during the 1st 2 weeks of flowering. The percentage of pods reaching maturity varied among cultivars. About 40% of the floral buds that developed on the determinate bean selection were retained to full pod maturity. Only 20% to 25% of the floral buds developed on each of the indeterminate cultivars were retained to full pod maturity. An increase in the MSMT from 0.05 to 0.1 MPa in the 23 June planting reduced the number of pods and seeds/plant and total seed weight/plant by 20% to 40%, but the number of seeds/pod and weight/seed was not influenced by MSMT or by number of pods produced on either of the dry bean cultivars or the breeding selection.

Open Access

Abstract

Chemicals often associated with pollen function in vitro were applied under field conditions to foliage of determinate, semi-determinate, and indeterminate beans (Phaseolus vulgaris L.) to evaluate pod and seed yield response. Sprays of calcium nitrate, boric acid, ethylenediaminotetraacetic acid, detergent “Micro”, and different sugars altered pod retention and seed yield, but response varied with bean source.

Open Access