DOUBLE KERNELED FRUITS IN ALMOND (PRUNUS-DULCIS MILL) AS RELATED TO PRE-BLOSSOM TEMPERATURES

A ten year study on the influence of pre-blossom temperatures on the p ercentage of double kerneled almond fruits, under warm climatic condit ions, showed a negative correlation between the percentage of fruits w ith double kernels and mean temperatures during the pre-blossom months . When mean temperatures for single pre-blossom months were correlated with double-kernel production, mean temperatures in December showed a much larger correlation (r = -0.78) than those of November (r = -0.51 ) or January (r = -0.31). Artificially induced 3-4 degrees C daytime i ncreases in pre-blossom temperature on the variety 'Malaguena' which c ommonly produces double kernels, caused a marked fall in the percentag e of double kerneled fruits, although it did not affect the percentage fruit set. Our results may indicate an important influence of pre-blo ssom temperatures on ovule viability.