Evaluation of the Concentration-Response Relationship between Film Antitranspirant and Yield of Rapeseed (Brassica Napus L.) Under Drought

Drought can cause large yield losses of rapeseed ( Brassica napus L.), particularly during the flowering stage. Effective methods of crop management are required to improve the tolerance to drought. Film antitranspirants (AT) help to reduce water loss by forming a waterproof layer to block stomata mechanically. Three pot experiments were conducted in the glasshouse to investigate the effects of AT at five concentrations on spring rapeseed with and without water stress over the flowering stage. Water stress depressed gas exchange significantly and reduced seed dry weight by an average of 70%. Linear decreases in stomatal conductance and photosynthesis rate with an increased concentration of AT were found in two of the three experiments for both well-watered and water-stressed plants. Increases occurred in some yield components, but reductions in other yield components meant that we did not see a significant improvement in seed yield from AT in water-stressed or well-watered plants. Our results indicate that the application of AT can be a method of mitigating the drought damage to rapeseed by blocking stomata to reduce water loss, and thus potentially sustaining seed yield, but higher concentrations than those tested may be needed in future studies