Abstract: Calcium distribution in the stigma and style of pepper ( Capsicum annuum L. cv. Xiangyan 1)under heat stress was investigated with potassium antimonite technique. The calcium precipitates emerged in the apoplast system , such as the stigma receptive surface and the intercellular spaces of the transmitting tissue in style,in which calcium precipitates firstly increased before pollen tube penetration , then decreased after that . Under heat stress , abundant calcium precipitates not only accumulated in the apoplast system , but also distributed in the cytoplasm and nucleus , and the pollen tube in the transmitting tissue showed some distortion and transfiguration. It suggests that those results may correlate with abnormalities in the distribution of calcium.

Key words: Pepper, Heat stress, Stigma, Style, Ca²⁺