Guan'gai paishui xuebao (Mar 2021)
Effects of Magnetization Irrigation on Photosynthesis, Mineral Elements and Yield of Lettuce Vary with Water Sources
Abstract
【Background and Objective】 Magnetizing the water prior to irrigation is a new technology developed over the past decades in China. The objective of this paper is to investigate how different irrigation water sources alter the effects of the magnetization on photosynthesis, physiological and biochemical characteristics, as well as the yield of lettuce. 【Method】 The experiment was conducted in a solar greenhouse with the Italian lettuce taken as the model plant. It consisted of non-magnetization (M0) and magnetization (M1); added to these are three irrigation water sources: fresh water (T1), reclaimed water (T2) and saline water (T3). Overall, there were six treatments which were arranged in the greenhouse by a randomized block design. For each treatment, we measured the net photosynthetic rate, transpiration rate, antioxidant enzyme activity, mineral element, yield and water use efficiency of the lettuce. 【Result】 Effects of the three water sources after magnetization on crop growth were different. For a given water source, there was no significant difference in the net photosynthetic rate between magnetization and non-magnetization in the early and late growth stage, but in the middle growth stage the magnetized fresh water and the reclaimed water increased the net photosynthetic rate of the crop by 11.16% and 14.73%, respectively. Saline water irrigation reduced the net photosynthetic rate at significant level, and there was no significant difference in net photosynthetic rate between the fresh water and reclaimed water irrigation. Magnetizing the fresh water, reclaimed and saline water increased the transpiration rate, despite not at significant, but they significantly boosted the activities of SOD by 18.08%, 12.77% and 14.68% respectively, the activities of POD by 20.97%, 18.14% and 16.99% respectively, and the activities of CAT by 22.54%, 23.09% and 18.55% respectively. In the meantime, magnetizing the fresh water and the reclaimed water increased the total nitrogen in the lettuce leaves by 7.71% and 6.83%, respectively. Magnetization also altered the content of P, Ca, Mg, Na and K in the leaves, with the alterations varying with water sources. For yield, magnetizing the fresh and the reclaimed water increased the yield by 9.42% and 10.15% at significant level, respectively, magnetizing the saline water did not lead to a noticeable change in the yield. M1T1 was most effective in improving yield and the above-ground dry mass, whereas M0T3 was the least effective. Compared with M0T3, M1T1 increased the yield and the above-ground dry mass by 33.44% and 31.29%, respectively. Depending on water sources, magnetization could also increase water use efficiency by 5.03%~11.65%. 【Conclusion】 Magnetizing the water in irrigating lettuce was beneficial to its physiological and biochemical activities such as photosynthesis and antioxidant enzyme activity, thereby increasing yield and water use efficiency. But the improvement depends on water sources. In our study, magnetizing the fresh water and the reclaimed water was more effective than the saline water.
Keywords
