Self-incompatibility in Spanish clones of apricot (Prunus armeniaca L.) tree
The present study is about some aspects of the reproduction physiology of twenty apricot clones ( Prunus armeniaca L.) grown in Abarán (Murcia, Spain). Self incompatibility of these clones was determined not only in field conditions in terms of the fruit set by means of self fertilization and free pollination, but also in laboratory conditions, by means of fluorescence microscopy of pollen germination on the stigma and of the growth of the pollen tube towards the egg. The only clone with signs of self incompatibility was ‘Moniquí Azaraque’. The clone with the lowest fertilization time was ‘Chicanos Archena’.
Methods for Determining Compatibility and Pollinator Efficiency in Temperate Fruit Species
Fruit yields depend on the successful achievement of a series of sequential processes from floral induction to fruitlet retention. For the successful set of an optimum crop load of most fruit cultivars, pollination and fertilization of flowers must be effective. In this paper, I describe the most commonly used methods for testing self-incompatibility and pollinator efficiency in the main fruit trees. Estimation of self-incompatibility can be done experimentally or genetically. Experimentally, comparisons following self- vs. cross- pollinations can be performed sequentially: (1) difference in fruit or seed sets; (2) different pollen germination and tube growth in the styles (self-incompatibility syndrome); (3) difference in ovule development (ovarian self-incompatibility) or cessation of embryo development after selfpollination (late-acting self-incompatibility). If seed set differences are not explained by differences in these pre-zygotic steps, inbreeding depression can be responsible. The genetic approach of incompatibility with the characterization of S-alleles can assess the compatibility level between cultivars. Finally, pollination effectiveness and pollinator efficiency can be assessed with direct and indirect measures. Direct measures focus on pollen deposition and retrieval on virgin flowers. Indirect measures include pollinator guild, relative abundance and behaviour, pollen carryover capacity and gene flow.
Incompatibility problems in species crosses of tulips
SummaryAn investigation into the conditions that lead to higher seed yields from species crosses of tulip has revealed that the temperature has an effect on seed production. Under constant temperatures, the best results in the phytotron were obtained at 14 °C.Various problems associated with such crosses have been explained on the basis of microscopical observations. One of the factors associated with a poor seed yield from interspecific tulip crosses is the abnormal growth of the pollen tubes in the embryo-sac cavities of numerous ovules, with the result that fertilization does not take place.The failure of the cross between Red Pitt, a Darwin tulip of the species T. gesneriana and the T. fosteriana tulips Mad. Lefeber and Princeps appears to be due to an inhibition of the pollen tube growth in the stigma.