Effect of plant film-forming anti-transpirant on transpiration efficiency of winter wheat flag-leaf

Restraining crop transpiration is critical for improving water use efficiency under scarce water resource conditions. Plant film-forming anti-transpirant (PFA) significantly limits plant water consumption, which in turn increases water use efficiency. However, PFA is rarely applied in winter wheat cultivation. We studied the effects of PFA on water stress physiology and senescence of flag leaf of winter wheat "Kn 9204" under different irrigations. The wheat was irrigated 0, 1, 2 or 3 times (respectively denoted as I0, I1, I2 and I3) during the entire period of growth. The results suggested that transpiration rates decreased, photosynthetic rates remained unaffected and transpiration efficiency increased under spray PFA treatment. Flag-leaf water retention under spray treatment was higher than that of CK. Excised-leaf water loss rate under spray treatment was lower by 10.3%, 10.3%, 12.8% and 16.9% under I0, I1, I2 and I3 irrigation treatments, respectively, than that of CK with increasing flag-leaf relative water content and water potential.Under 1, 2 or 3 times of irrigation, wheat superoxide dismutaseon (SOD) and catalase (CAT) activities dropped. Under zero irrigation, however, SOD and CAT activities exceeded that of CK. The rate of change (rate of curve) in malonyldiadehyde content under different treatments ranked as follows: I1+CK (10.59) > I1+PFA (6.99) > I2+CK (5.05) > I2+PFA (3.66) > I3+CK (2.36) > I3+PFA (1.56). This suggested that spray PFA slowed down flag-leaf senescence as it maintained a water condition that restrained active oxygen (AO) production, ensured AO normal scavenging and sustained integrated cell membrane. Hence the high photosynthetic rate coupled with low transpiration rate induced high water use efficiency. Physiologically, this increased water use efficiency under spay PFA treatment. On the basis the results, it was concluded that PFA reduced flag-leaf transpiration and eased dry/hot-wind stress in winter wheat. Despite these findings, it was recommended to continue active research into the effects of spay PFA treatment on winter wheat production.