Abstract
Summer vegetables production is enormously influenced by elevated temperature above thresh hold level which finally brings
about a threat to food security in Indo-Pak region. Genetic variability is a significant tool to address this issue. The current
study was intended to screen out heat tolerant cucumber genotypes and assessment of certain heat tolerant and sensitive
genotypes for some water related, physiological and biochemical attributes. After one-month emergence of seedlings of twentyfive cucumber genotypes were subjected to elevated temperature (40°C/32°C day/night) for one week. Selection of cucumber
genotypes for heat tolerance and sensitive was done based on several morphological, physiological and biochemical attributes.
Substantial variation among genotypes was observed according to their capability to tolerate heat stress. Genotypes L3466 and
Desi-cucumber (having electrolyte leakage of 50.5 and 46.5%, respectively) were found the most heat tolerant, while Suyo
Long and Poinsett were found sensitive to heat stress (having electrolyte leakage of 52.3 and 54.5%, respectively). The
significant difference was observed in water-related attributes, antioxidant activities, osmoprotectants and lipid peroxidation
in leaves of tolerant (L3466 and Desi-cucumber) and sensitive (Suyo Long and Poinsett) genotypes under heat stress
(40°C/32°C) when further analyzed. It was concluded that a few genotypes were more tolerant to elevated temperature (40°C)
than others under study.
