Abstract: By using principles of quantitative genetics, genetic effects of five fruit characters of summer squash were analyzed. The results indicated that genetic patterns of all five characters fitted additive and dominant model. Different degree of dominant effects and additive effects existed among five characters of summer squash in three combinations. Most characters of fruit length ( FL) , fruit diameter ( FD) , fruit index ( FI) and fruit flesh thickness ( FFT) in three combinations showed positive dominant effects that were close to or beyond corresponding additive effectswhile fruit stalk length ( FSL) had negative dominant effect. Broad and narrow heredity abilities of FL, FD and FI were bigger and that of FSL and FFT were smaller.

Key words: Summer squash, Fruit, Genetic effects