Effects Of Calcium And Inhibitor On Physiological And Biochemical Characteristics Of Cucumber In Greenhouse Under Root Zone Low Critical Temperature

Aim at the question of low root zone temperature in solar greenhouse, effects of calcium on physiological and biochemical characteristics of cucumber in greenhouse under root zone low temperature were studied by increasing concentrations of Ca²⁺ in nutrient solutions. The main result was as follows:1. When root zone temperature was lowered(8¹0℃), root activity and photosynthesis of cucumber seedlings were decreased; SOD, POD, CAT activity of leaf and root were decreased; contents of MDA and electrolytic relative leakage were increased; the absorption of elements were decreased significantly. With increasing concentrations of Ca²⁺ in nutrient solutions, root activity, POD and CAT activity were increased at first, and then decreased later; SOD activity , contents of MDA and electrolytic relative leakage were decreased at first and then increased ; the absorption of K was increased; the absorption of P, Ca, Fe, Mn, Cu, Zn were increased at first, and then decreased later; the absorption of Mg was decreased.2. When root zone temperature was lowered, Ca²⁺-ATPase, H⁺-ATPase activity in plasma membrane and tonoplast of cucumber seedlings were decreased. In accordance with increasing concentrations of Ca²⁺, Ca²⁺-ATPase and H⁺-ATPase activity in plasma membrane and tonoplast of cucumber root were increased significantly at first, then decreased slightly later; H⁺-ATPase activity in plasma membrane and tonoplast of cucumber leaf was changed unremarkably; Ca²⁺-ATPase activity in plasma membrane and tonoplast of cucumber leaf was increased significantly at first, then decreased slightly later.3. When root zone temperature was lowered, contents of ABA and CaM were significantly increased. With increasing concentrations of Ca²⁺(10.5 mmol·L^-1), contents of ABA were increased but CaM was decreased.When adding EGTA (LaCl₃) in nutrient solutions, contents of ABA was return a certain extent, and contents of CaM was seriously decreased.4. When increasing Ca²⁺ (10.5 mmol·L^-1) and EGTA (LaCl₃) in nutrient solutions, SOD activity was return a certain extent; POD, CAT activity; electrolytic relative leakage were increased slightly.