Abstract
The effect of salicylic acid (SA, 100 μM) of various duration on some indexes of CO 2 -gas exchange, water regime, growth and cold resistance of wheat plants ( Triticum aestivum L.) under optimal (22 °C) and low hardening (4 °C) temperatures were studied. For this, week-long seedlings throughout the whole experiment (7 days) were kept on a nutrient solution with added SA at 22 and 4 °C (prolonged SA action) or kept for 1 day at 22 °C on a nutrient solution with SA and then on a solution without SA (within 6 days) exposed to temperatures of 22 and 4 °C (pre-treatment of SA). It was shown that at a temperature of 22 °C, the prolonged action of SA led to a decrease in the rate of visible photosynthesis and the ratio of respiration in the process of CO 2 -gas exchange, did not affect water use efficiency (WUE), increased the biomass of shoot and root. On the contrary, diurnal exposure to SA had virtually no effect on the dynamics of CO 2 assimilation, reduced the ratio of respiration in CO 2 -gas exchange and transpiration, but increased the WUE. At a temperature of 4 °C, the continuous action of the SA contributed to maintaining the rate of photosynthesis at a higher level than in the control, reduced the ratio of respiration in CO 2 -gas exchange, increased WUE, and also stabilized the accumulation of plant biomass. In contrast, the diurnal pretreatment of the SA increased the negative effect of low temperature on the assimilation of CO 2 , led to increase in expenses of respiration, did not affect the level of transpiration, caused a decrease in WUE. It is important, that the exogenous SA contributed to the growth of the cold tolerance of wheat in conditions of normal and low hardening temperatures. Thus, the response of wheat plants to the effect of SA depends on its duration, while the nature of changes in physiological processes differ under optimal and low temperatures.
Highlights
It was shown that at a temperature of 22 °C, the prolonged action of SA led to a decrease in the rate of visible photosynthesis and the contribution of respiration to the process of CO2‐gas exchange, did not affect water use efficiency (WUE), increased shoot and root biomass
At a temperature of 4 °C, the prolonged exposure to SA contributed to maintaining the rate of photosynthesis at a higher level than in the control, reduced the contribution of respiration to CO2‐gas exchange, increased WUE, as well as stabilized the accumulation of plant biomass
The 24‐h pre-treatment with SA intensified the negative effect of low temperature on CO2 assimilation, increased the costs of respiration, did not affect the level of transpiration, caused WUE to decline
Summary
Институт биологии КарНЦ РАН, ФИЦ «Карельский научный центр РАН», Петрозаводск, Россия. The effect of salicylic acid (SA, 100 μM) of various durations on some indexes of CO2‐gas exchange, water regime, growth and cold resistance of wheat plants (Triticum aestivum L.) under optimal (22 °C) and low hardening (4 °C) temperatures were studied. To this end, week-old seedlings were either kept throughout the experiment (7 days) on a nutrient solution with SA at 22 and 4 °C (prolonged SA action), or kept on a nutrient solution with SA for 1 day at 22 °C and another 6 days on a solution without SA at 22 and 4 °C (pre-treatment with SA). Цель данного исследования заключалась в изучении влияния продолжительности воздействия СК на некоторые показатели СО2‐газообмена, водного режима, роста и холодоустойчивость растений пшеницы, находящихся в условиях оптимальной или пониженной температуры
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