The effect of growth regulators on photosynthesis and water regime of sugar beet during water stress
2010
Hejnak, V.,Ceska Zemedelska Univ., Prague (Czech Republic). Katedra Botaniky a Fyziologie Rostlin
The effect of abscisic acid (ABA), synthetic cytokinin benzylaminopurine (BAP) and the Atonik growth stimulator on photosynthesis rate (PN), transpiration rate (E) and water use efficiency (WUE) was studied during water stress of sugar beet. Young plants of the Takt variety were grown under managed conditions in a greenhouse. Growth regulators were applied on leaves during the water stress of the plants as follows: 100 microM solution of ABA, 1 microM, 10 microM solution of BAP and 0.1% solution of Atonik. Moderate water stress significantly reduced the photosynthesis rate and transpiration rate. However, the plants achieved a much better water management; their water use efficiency was higher than that of the plants growing under normal soil moisture conditions. Shortly after application, ABA was closing stomata and was reducing the photosynthesis and transpiration rates. Consequently, it slowed down the progress of water stress in the treated plants. This is why the plants achieved a higher photosynthesis rate at a later stage of water stress with virtually the same water use efficiency like the plants stressed by drought but not treated by growth regulators. The highest photosynthesis rate was achieved by the plants treated by BAP and Atonik. The used concentration of 1 microM BAP was also the best alternative as concerned water use efficiency. The experiment confirmed the importance of choosing the right concentration of the substance. With a higher concentration of BAP (10 microM), the high photosynthesis rate was accompanied with high transpiration. This significantly deteriorated water use efficiency. Similarly, the concentration of Atonik was probably too high; therefore in this case, too, worse water use efficiency was achieved. During a long-term drought, the use of too high concentrations of BAP or Atonik can result in fast drainage of water and, ultimately, in deterioration of the water stress.
显示更多 [+] 显示较少 [-]