Abstract: To study the fruit development of pitaya under saline habitats, weights of the whole fruit, flesh and peel, as well as the moisture contents and dry material were monitored. The results showed that pitaya fruit-weight increased in a "double S" curve as the plant grew in saline habitats. The weights of the fresh and dry fruits reached their maximums upon ripening. The peel played a predominant role on the weight gain in the initial growth stage (i. e. , 6--15d after flowering), while the flesh did in the mid-to-late growth stage (i. e. , 21--35d after flowering). Moisture content in the flesh dictated the fruit's weight gain. The greatest weight gain rate of the flesh occurred during 26--30d after flowering; and that of the fruit and peel, 6--lOd after flowerinm