Foliar Fertilization for Sustainable Crop Production
Foliar Fertilization for Sustainable Crop Production
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DOI：
10.1007/978-90-481-8741-6_13
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发表时间：
2010-01-01
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影响因子：
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通讯作者：
Kannan, Seshadri
中科院分区：
文献类型：
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作者：
Kannan, Seshadri
除了二氧化碳和水之外，植物还需要无机营养素来生长和生产。养分存在于土壤中，但除非通过施肥来提供，否则会耗尽。土壤喂养是正常的做法，但在其对植物的可用性方面存在局限性。磷、钾等元素和大多数微量营养素都固定在土壤复合体中，而氮等可溶性更强的营养素很容易从土壤中滤出。通过沥滤流失的水进入含水层，污染地下水。例如，硝酸盐和磷酸盐可能对人体有害。随着为化肥生产提供原材料的化石燃料成本的增加，需要在化肥使用技术方面找到创新。叶面喷施就是这样一种技术。在这里，我回顾了大量的工作，已进行的叶面施用养分的有效性，叶面吸收和运输的机制。综述了植物叶片的角质膜、表皮毛、角质孔、外展枝等组成成分的性质及其在植物叶片营养物质运输中的作用。Cu2+对以水性形式存在的营养离子是可渗透的，并且具有独特的结构，如孔。但不知道这些气孔是否有助于进入叶细胞。毛状体通过提供更多的吸收面积来增加运输到叶中的量。角质层有角质和角质蜡两种亲脂性物质，它们不同程度地影响着营养离子的渗透性，营养物质穿透角质层后到达叶细胞，再通过胞间连丝转运到其它部位。某些微量营养素不像主要营养元素如N、P或K那样自由移动的。叶片的年龄和喷雾液的pH值对叶面吸收很重要。保卫细胞和表皮细胞之间缺乏胞间连丝也是重要的。有一种元素Cl能迅速地从施入的叶片转移到其它部位，表明它是自由移动的。Wallace等人提出的限制因子概念和最大值定律有助于提高产量平台，当土壤供应成为“限制”因子时，叶面补饲有助于提高作物产量。利用现代喷灌技术，可以将灌溉水中的营养元素补充到叶面施肥中，从而实现叶面施肥的经济性。叶面营养是纠正微量元素缺乏的有效措施，对提高产量具有重要意义。作物育种者也可以帮助进化品种，这些品种对叶面喂养有很好的反应。
Plants require inorganic nutrients in addition to carbon dioxide and water for growth and production. Nutrients are present in soil, but get depleted unless supplied through fertilization. Soil feeding is the normal practice, but has limitations with respect to its availability to the plants. The elements such as phosphorus, potassium, and most of the micronutrients are fixed in the soil complex, while the more soluble nutrients such as nitrogen are easily leached down the soil. What is lost through leaching reaches the aquifer and pollutes the groundwater. For instance nitrates and phosphates can be harmful to humans. With increasing costs of fossil fuel, which provides the raw materials for fertilizer manufacture, there is a need to find innovations in fertilizer usage techniques. Foliar application is one such technique. Here I review the extensive work that has been carried out on the effectiveness of foliar-applied nutrients, the mechanisms of foliar absorption, and transport. The leaf components such as the cuticular membranes, the trichomes, the cuticular pores, ectoteichodes, their properties, and their role in the nutrient transport into the plant leaf are reviewed. Cuticles are permeable to nutrient ions present in aqueous forms and have distinct structures like pores. But it is not known if these pores facilitate easy entry into the leaf cells. The trichomes increase the amount transported into the leaf by providing more area for absorption. The cuticles have two types of lipophilic substances, the cutin and the cuticular wax, which influence the permeability of nutrient ions to varying degrees.It is clear that nutrients reach the leaf cells, after penetrating the cuticle, and are further transported to other parts through plasmadesmata. Some micronutrients are not as freely mobile as the major nutrient elements such as N, P, or K. The age of the leaf and the pH of the spray liquid are important for foliar absorption. The absence of plasmadesmatic connections between the guard cells and the epidermal cells is also important. One element Cl has been found to be transported from the applied leaf to other parts rapidly, showing it is freely mobile. This should be true for many anions.The concept of limiting factors and the law of the maximum proposed by Wallace group are useful in raising the yield plateau, and when soil supply poses the "limiting" factor, foliar feeding will help increase the crop yield. Modern technique of sprinkler irrigation system can be exploited to supply the nutrient elements in the irrigation water, which will be economical in foliar fertilization. Foliar nutrition is very practical to correct micronutrient deficiencies, which are very important for maximizing the yield. Crop breeders could also help evolve cultivars, which give good response to foliar feeding.