Impact of Heat Stress on Cauliflower (Brassica Oleracea var. Botrytis): A Physiological Assessment
Impact of Heat Stress on Cauliflower (Brassica Oleracea var. Botrytis): A Physiological Assessment
Saba Aleem1*, Iram Sharif2, Mehvish Tahir3, Muhammad Najeebullah3, Ali Nawaz1, Muhammad Imran Khan1, Amina Batool1 and Waheed Arshad1
ABSTRACT
Due to the global increase in temperature, heat stress has become a great threat for the crops production worldwide. This research was conducted to assess the genotypic variability and relationship of accumulation of glycine betaine, proline, chlorophyll contents, and cell membrane thermostability with yield in different cauliflower varieties under heat stress. Heat stress was imposed by early sowing of genotypes (in July as compared to September sowing). Under the early sown condition, the high temperature was experienced by the plants during the curd development stage. Heat tolerance ability of the genotypes was assessed by their ability to curd induction and development at high temperature and also based on different physiological traits. Heat susceptible genotypes showed lengthened curd induction stage. Further, decrease in chlorophyll and osmoprotectants contents was also seen in heat susceptible genotypes. TSX-C40 was identified as most susceptible genotype to heat stress due to low accumulation of glycine betaine and proline, and greater relative cell injury percentage, along with lengthened curd induction stage. Curd induction in TSX-C40 was seen when the maximum temperature was between 21.5-26.0 ˚C. While CF-Early was identified as heat tolerant genotype as curd induction was started at an average maximum temperature of 34 ˚C. Further CF-Early showed high chlorophyll contents, and more glycine betaine, and proline accumulation. Less relative cell injury percentage resulted in less damage to cell membranes and the protection of the photosynthetic apparatus during the heat stress of CF-Early. In addition, the accumulation of more osmoprotectants in CF-Early may lead to reactive oxygen species scavenging to protect cell membranes.
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