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  • Author or Editor: Salvador Perez x
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Abstract

Eighteen species of Prunus and 4 interspecific hybrids from the 3 main subgenera were used to ascertain the prezygotic mechanisms that maintain reproductive isolation. The percentage of pollen germination of pure species was very high (82% to 97%), and ranged from 1% to 97% for interspecific hybrids. Pollen tube growth rates differed greatly among species and ranged from 3.8 to 8.7 mm/day in vitro, and from 3 to 12 mm/day in vivo. These values were highly correlated with pistil length (r = 0.90) and pollen volume (r = 0.91). Evidence was obtained suggesting the existence of additional incompatibility mechanisms, the 1st preventing interspecific fertilization in the subgenus Cerasus. In P. avium L., the pollen tubes of some species are inhibited and finally arrested before they reach the first half length of the style. In crosses involving P. cerasus L. and P. serotina Ehrh., the use of the latter as the seed parent showed a 10-fold increase in fruit set when compared to the reciprocal. Secondly, differences in pistil length and in pollen tube growth rate among species provide a sound basis for explaining the phenomenon of unilateral incompatibility in Prunus. The use of male-sterile genotypes of P. persica L., which had a prolonged period of receptivity, gave increased fruit set and showed increased potential for overcoming the prezygotic incompatibility barriers.

Open Access

The storage of persimmon cv. Rojo Brillante (Diospyros kaki L.) at low temperatures is limited by the susceptibility to chilling injury (CI), the main symptom being a drastic reduction of firmness when the fruit are transferred from low to moderate temperature. 1-Methylcyclopropene (1-MCP), an ethylene action inhibitor, has been shown to alleviate CI of persimmon, prolonging the storage period. In this article, the microstructural changes produced in the flesh of chilling-injured persimmon and fruit treated with 1-MCP were studied. The drastic softening displayed by chilling-injured fruit was related to a loss of cell wall integrity as well as to low intercellular adhesion. 1-MCP treatment alleviated CI by preserving the fruit firmness; it was linked to a preservation of the cell wall's integrity and to a higher intercellular adhesion observed during storage at low temperatures as well as when fruit were transferred to shelf temperatures.

Free access