Determination of Heat Tolerance of Interspecific (Cucurbita maxima x Cucurbita moschata) Inbred Line of Squash ‘Maxchata’ and Its Parents through Photosynthetic Response

Authors : Neelam ARA, Jing YANG, Zhong HU, Ming ZHANG

Pages : 188-197

Doi:10.1501/Tarimbil_0000001244

View : 18 | Download : 9

Publication Date : 2013-09-29

Article Type : Research Paper

Abstract :Abstract Development of heat tolerant cultivars is the need of hour to combat the challenges of global warming and food supply to increasing population. This study was conducted to determine the extent of heat tolerance of newly developed interspecific inbred line of squash named as ‘ Maxchata ’ through comparing its photosynthetic attributes with its parents C. maxima and C. moschata . Plants of these three cultivars were subjected to three different temperatures i.e 30 ° C day/ 25 ° C night as control, 37 ° C day/ 32 ° C night as moderate heat stress and 42 ° C day/ 37 ° C night as severe heat stress, for seven days. Results showed that various gas exchange attributes like photosynthetic rate insert ignore into journalissuearticles values( P N );, stomatal conductance insert ignore into journalissuearticles values(g s ); and transpiration rate insert ignore into journalissuearticles values(E); as well as chlorophyll florescence insert ignore into journalissuearticles values(F v /F m ); all dropped significantly in the studied cultivars with increasing temperature, while intercellular CO 2 concentration insert ignore into journalissuearticles values( Ci ); increased pointing to the nonstomatal limitations. Further, chlorophyll pigments also degraded with heat shocks resulting in more Chl a to b ratio and decreased chlorophyll carotenoids ratio. However, these trends were more abrupt in C. maxima , chased by ‘ Maxchata’ and then C. moschata . Hence, C. moschata had the best photosynthetic machinery to sustain the heat regimes, followed by ‘ Maxchata ’, while, C. maxima was the most susceptible. So, ‘ Maxchata ’ with some degree of heat tolerance has the ability to cope with the climate change.
Keywords : Chlorophyll florescence, cucurbits, gas exchange, heat stress, pumpkin, thermotolerance