AP BIOLOGY

Detailed explanation-1: -Sucrose is use for pollen germination as it helps in formation of pollen tubes, in vitro.

Detailed explanation-2: -Calcium and Turgor Formation during Pollen Tube Growth The production and maintenance of internal turgor in pollen and the pollen tube provide the driving force for pollen germination and tube growth.

Detailed explanation-3: -Once a pollen grain settles on a compatible pistil, it may germinate in response to a sugary fluid secreted by the mature stigma. Lipids at the surface of the stigma may also stimulate pollen tube growth for compatible pollen.

Detailed explanation-4: -Optimal sugar concentration for pollen germination was 300 g L–1, in which up to 81 % of pollen grains showed fast germination. Germination and emergence of multiple tubes were observed in sucrose concentrations of 100–800 g L–1.

Detailed explanation-5: -Pollen germination rates and tube growth were recorded periodically at 1, 12, 24, and 48 h. The results showed that sucrose imposes significant effects on pollen germination and tube growth. The effects are most obvious at concentration of 15%. Boric acid significantly promoted germination and tube growth.