Title : Plant sex: How hot is too hot? Reproductive screening for heat tolerance in cotton.
Abstract:
Lacking voluntary locomotion, plants are highly susceptible to the stresses of their immediate surroundings. In particular, abiotic factors such as high temperature and low moisture can have adverse effects on cotton (Gossypium spp.) including negative effects on plant growth, development, and subsequently yield. There is a general lack of studies focusing on cotton reproductive characteristics as an early indicator of stress tolerance despite the direct impact on boll (fruit) production. Because plant sexual reproduction and especially pollen is highly sensitive to the environment, the aim of this study was to investigate floral pollen tube germination and growth as well as boll development under both temperature and water stress. In this study, we grew cotton cultivar Sicot 746 B3F in both irrigated and non-irrigated (rainfed) systems. To impose a heat stress, open top chambers were used in both irrigation conditions. Flowers at zero days post anthesis were collected from these treatments for in vivo microscopic analysis to quantify the germination percentage and tube length of successfully deposited pollen on floral stigmas. In addition, open flowers were tagged for boll analysis of seed number and size, lint percentage, and fibre quality at the end of the growing season. We hypothesized that elevated temperature and water stress as individual stressors would decrease the percent germination and tube length of pollen into the floral style of cotton plants and that seed set would be negatively impacted. It was expected that applying both heat and water stress simultaneously would have a cumulative negative effect on these early reproductive traits. This research will be used to understand the physiology and floral biology of cotton under stressful environmental conditions, which will help develop early screening tools in cotton breeding.
