Effect of application of growth regulators on the physiological and yield parameters of winter wheat under water deficit

Abstract

The objective of this study was to evaluate the effect of growth regulator applications on yield and physiological parameters of winter wheat (Triticum aestivum L.) under water deficit. Water deficit was induced artificially by using rain-out shelters in period between booting and late milk ripeness. The effect of growth regulators was evaluated in two contrast years in terms of yield formation (2014)(2015). In both years the water deficit caused a significant reduction of grain yield. The negative effect of water deficit was partly alleviated by application of growth regulators. However, the effect of individual growth regulators varied depending on year. In favourable conditions for grain filling (2014) the alleviating effect was more pronounced in application of azoxystrobin which slows down the leaf senescence. On the contrary, in the year with suitable conditions for tillering (2015), the alleviating effect was most apparent in application of chlormequate-chloride. The applications of trinexapac-ethyl and ethephon showed small reduction of negative effect of water deficit consistently in both years. The CO 2 assimilation rate and stomatal conductance were recovered particularly by applications of chlormequate-chloride and azoxystrobin. Chlorophyll content and chlorophyll fluorescence parameters were more affected by water deficit in 2014, and the alleviating effect of growth regulators corresponded with yield response.

A Leaf Disc Assay for Evaluating the Response of Tea (Camellia sinensis) to PEG-Induced Osmotic Stress and Protective Effects of Azoxystrobin against Drought

“…AZ is a fungicide for control crop diseases and is also considered as a growth regulator that would recover CO 2 assimilation rate and stomatal conductance [ 21 ]. Additionally, the application of AZ increased water use efficacy, cell membrane stability, enzymatic antioxidant systems (catalase, peroxidase, polyphenol oxidase), total phenols, root growth to improve drought tolerance, and fruit yield in tomato [ 24 , 25 ].…”

“…Our previous study revealed that exogenous AZ inhibited photochemical and photo-protection parameters and led to severe photodamage in wheat seedlings under heat stress [ 39 ]. Barányiová and Klem [ 21 ] also indicated that the application of AZ during drought was unconducive to chlorophyll fluorescence because of reduced stomatal conductance and blocked gas exchange in wheat that was not infected by fungus. The recommended concentration of AZ application in tea gardens is 0.125 g L −1 with a 21-day pre-harvest interval in Taiwan, therefore 0.125 and 1.25 AZ g AZ L −1 were applied in this study.…”

“…The lower photochemical reaction in leaf discs at high concentration AZ implies that tea leaves have to dissipate excessive light energy via regulated and non-regulated mechanisms. More severe photo-damage with less photo-protection in leaf discs at high concentrations of AZ also indicates that tea leaves may suffer serious oxidative stress under these conditions [ 21 ]. Moreover, declines in total Chl and Chl a/b in PEG-treated leaf discs, both with and without AZ ( Table 2 ), suggests that AZ did not influence chlorophylls in this study.…”

“…Likewise, azoxystrobin (AZ), one kind of strobilurin, provided a similar function in crop production [ 17 , 18 , 19 , 20 ]. Some studies illustrated that the application of AZ improved nitrogen use and physiological traits in photosynthesis, antioxidant status, and delaying senescence in wheat and decelerated chlorophyll degradation in harvested lettuce [ 20 , 21 , 22 , 23 ]. Moreover, applying AZ-enhanced water use, root architecture, and yield in tomatoes during drought stress.…”

“…Moreover, applying AZ-enhanced water use, root architecture, and yield in tomatoes during drought stress. AZ treatment also prevented leaf senescence, enhanced photosynthetic physiology and yield in wheat under water deficit [ 21 , 24 , 25 ]. Additionally, AZ was shown to have low toxicity to mammals and a lower residue in harvested food [ 26 ].…”