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硝酸钙在土壤中累积导致植物生长异常是温室栽培中常见的问题之一。高量硝酸钙何以会引起生长异常尚不十分清楚。本文从植物对硝酸根和钙的生理反应方面进行了探讨。植物对硝酸根的吸收与还原可引起根表和根细胞质pH上升,诱导植物缺铁,高量硝酸根对根系细胞质膜硝酸还原酶的诱导可引起亚硝酸根在根表形成,抑制根系尤其是根毛的生长和养分的吸收;细胞质膜硝酸还原酶有可能促进氧化锰在根表还原而利于锰在植物中的累积。高量可溶性钙既抑制其他阳离子的吸收,又通过对液泡膜阳离子/H+交换体的诱导,促进钙、锰、锌等离子在液泡中累积,加剧养分缺乏的程度。高硝态氮引起的高细胞质pH和可溶性有机氮含量等等,既可导致缺素症又可致抗病性下降,可能是病害容易发生的生理学原因。控温不好的温室如塑料大棚,昼夜温差大,易加剧细胞质pH的波动,促进离子或溶质在液泡中的累积,易加剧营养失衡,可能是温室生理障碍易发生的环境因素。
Accumulation of calcium nitrate in the soil leading to abnormal plant growth is one of the common problems in greenhouse cultivation. It is not clear why a high amount of calcium nitrate causes abnormal growth. This article explores the physiological responses of plants to nitrate and calcium. Plant nitrate uptake and reduction can cause root and root cytoplasm pH rise induced by plant iron deficiency, high amount of nitrate on the root cell plasma membrane nitrate reductase induced nitrite can cause root formation in the root, especially the inhibition of the root system Root hair growth and nutrient uptake; the cytoplasmic membrane nitrate reductase is likely to promote the reduction of manganese oxide in the root surface and facilitate the accumulation of manganese in the plant. High amount of soluble calcium not only restrain the absorption of other cations, but also promote the accumulation of calcium, manganese and zinc ions in vacuoles through the induction of tonoplast cation / H + exchangers and aggravate the degree of nutrient deficiency. The high cytoplasmic pH and soluble organic nitrogen content caused by high-NO3-N can not only lead to deficiency but also decrease the disease resistance, which may be the physiological reason for the easy disease occurrence. Greenhouses with poor temperature control, such as plastic greenhouses, have large temperature differences between day and night, exacerbate the fluctuation of cytoplasm pH and promote the accumulation of ions or solutes in the vacuoles, which may aggravate the imbalance of nutrients and may be an environmental factor prone to physiological barriers in greenhouse.