碱胁迫下磷酸脲降低土壤pH值促进菠菜生长

Decreasing soil p H value to promote spinach growth by application of urea phosphate under alkaline stress

为明确磷酸脲缓解菠菜碱胁迫的作用效果,该文以大叶菠菜为材料,研究了碱胁迫下磷酸脲对土壤p H值、植株生长、叶片生理特性的影响。试验设无碱胁迫处理、碱胁迫处理、碱胁迫后灌溉无机肥液处理、碱胁迫后灌溉磷酸脲液处理,结果表明:碱胁迫6d后,施入磷酸脲、无机肥溶液均显著降低土壤p H值,分别比碱胁迫不施肥处理降低2.69、0.86个单位。碱胁迫后灌溉磷酸脲液处理显著提高叶片超氧化物歧化酶(superoxide dismutase,SOD)、过氧化物酶(peroxidase,POD)和过氧化氢酶(catalase,CAT)活性,分别比碱胁迫处理提高7.96%、26.75%、57.70%,丙二醛(malondiadehyde,MDA)含量降低了10.63%,进而减轻了膜脂过氧化程度,显著提高叶片光合色素叶绿素a、b及类胡萝卜素含量,促进菠菜的生长,表现为碱胁迫后灌溉磷酸脲液处理的株高、叶面积、整株干质量分别比碱胁迫处理提高23.55%、21.03%、33.84%;而碱胁迫后灌溉无机肥液处理加剧碱胁迫程度,抑制菠菜生长,降低其生理特性,其叶绿素a、b及类胡萝卜素质量分数比碱胁迫后灌溉磷酸脲液处理降低19.84%、37.15%、14.15%。这说明磷酸脲溶液可以有效减轻菠菜碱胁迫程度,能作为碱化土壤的改良剂,为碱土地植物安全生产提供技术手段。

Soil alkalization is one of major environmental problems which adversely affect growth and development of plant and crop yield in agricultural production all over the world. Effective measures should be taken to reduce the impact of alkaline stress on plant growth. Urea phosphate is a new-type compound fertilizer in the drip-irrigation. It can generate acid after hydrolysis, but it is unclear if it can improve soil pH value and plant growth after applying to alkaline soil at present. Therefore, this study was conducted to test the effects of urea phosphate solution on soil pH value, plant growth and physiological characteristics of large-leaf spinach. The alkaline stress was simulated by irrigating 5 mL /d solution which was a mixture of 300 mmol/L Na HCO3 solution and 300 mmol/L Na2CO3 solution at 1：1 molar ratio for 6 d in a greenhouse. Four treatments were set in a random complete block design in this paper, including CK（Non-alkali stress）, AS treatment（adding 5 mL deionized water after alkali-stress）, AS＋FT treatment（adding 5 ml inorganic fertilizer solution after alkali-stress which was mixed with diammonium phosphate and urea solution and had a concentration equal with urea phosphate solution） and AS＋UP treatment（adding 5 ml urea phosphate solution after alkali-stress）. The results showed that the soil p H value was significantly increased by 44.19% after alkali-stress, but it were significantly decreased by 2.69 and 0.86 when applying urea phosphate solution and inorganic fertilizer solution to soil 6 days after alkaline stress, and urea phosphate solution had better effect than inorganic fertilizer solution on improving soil p H value. Compared to AS treatment, superoxide dismutase（SOD）, peroxidase（POD） and catalase（CAT） activities in AS＋UP treatment were significantly increased by 6.42%, 42.08% and 55.13%, respectively, malondiadehyde（MDA） content was significantly reduced by 10.62% and then the extent of membrane lipid was obvious alleviated. Meanwhile, photosynthetic pigment content was greatly improved after applying urea phosphate solution. Chlorophyll a, chlorophyll b and carotenoid concentrations of AS＋UP treatment were increased by 22.36%, 32.06% and 10.88%, respectively. Improvement effect on spinach seedlings growth in AS＋UP treatment was superior to AS treatment, and plant height, whole leaf area and dry substance of spinach of AS＋UP treatment were respectively 23.55%, 21.03% and 33.84% higher than AS treatment. However, the seedling growth in AS＋FT treatment was inhibited and physiological characteristics of spinach leaves were decreased. Compared to AS treatment, SOD, POD and CAT activities in AS＋FT treatment were reduced by 15.33%, 29.06% and 51.15%, respectively, and its MDA content was higher than that of AS treatment, so chlorophyll a, chlorophyll b and carotenoid contents were decreased by 19.84%, 37.15% and 14.15%, respectively. Moreover, leaf area, dry matter weight and root length were also respectively 26.47%, 26.16% and 1.65% lower than AS＋UP treatment. This research indicates that urea phosphate solution has positive effects on improving soil condition and enzyme activity under alkaline stress. Therefore, it can be promoted as a kind of soil amendment to reduce soil pH value in alkaline soil, enhance the ability to adapt to alkali stress and ensure the normal growth and development of crop plants, and it may be a valid method to increase land use efficiency and mitigate the pressure of land demand.