which desiccated pollen grains undergo usually occuron which are regulated both temporally and spa-tially. For pecan, pollen becomes rounded and hydrated by 1 hrafter pollination and pollen tube emergence is visible within 3 h(Wetzstein, 1989).germination rate at high temperature sometimes was accompanied by high burst (Figs. 4B and D and 5C andF). But there are also some deficiency in the current germination process when taking the pollen tube length as an indicator of pollen viability since the growth of pollen tube seemed more