Foliar application of sulfur improved growth, yiled and physiological attributes of canola (brassica napus L.) under heat stress conditions

Canola (Brassica napus) is a significant oilseed crop in the world, including in Pakistan. Increases in global temperatures will likely affect future plant species distribution, and could influence the survivability of individual species because of the relationship between temperature, germination and dormancy. The objective of this study was to improve heat tolerance in canola with the foliar application of sulfur. Therefore, a pot study was performed in a growth room at the Institute of Horticultural Sciences, University of Agriculture Faisalabad in 2017-2018 under controlled conditions. Two varieties of canola, i.e., Hyola-401 and 45S42, two levels of foliar sulfur (S-0= 0 ppm and S-1 500 ppm) treatments, and two temperature levels (T-1=18 degrees C and T-2=28 degrees C) were studied. Heat stress was imposed at the time of anthesis (55-60 days after emergence). Collected data indicated that morphological characters such as root shoot length and their fresh and dry weight showed better performance where foliar sulfur was applied either in heat stress as well as in control conditions where no heat stress was imposed. The photosynthetic rate (6.21 mu mole CO2 m(-2)/sec), stomatal conductance (0.12 mu mole CO2 m(-2)/sec) and intercellular CO2 concentration (346.13 mu mole CO2 m(-2)/sec) were improved in sulfur treatments under heat stress conditions while transpiration rate (0.51 mol H2O m(-2) s(-1)) was decreased with foliar application of sulfur. Similarly, yield and yield components (No. of siliques per plant (23), No. of seeds per siliqua (20), 1000 seed weight (3.53 g) and overall yield (2.11 t/ha) increased where foliar sulfur was applied @ 500 ppm. Overall results concluded that the foliar application of sulfur may be helpful for plant tolerance against heat stress by improving the physiological attributes and yield characters in canola. Moreover, among the genotype of Brassica napus L, Hyola 401 performed better in comparison with genotype 45S42 where foliar applied sulfur under heat stress conditions.