不同阳离子组成微咸水灌溉对生菜光合和离子吸收特性的影响

为探究不同微咸水水质对土壤盐分和作物生长的影响,在日光温室条件下,以生菜为供试对象开展盆栽试验,以CaSO4的饱和溶液为对照(CK),向去离子水中添加氯化盐形成不同阳离子组成的微咸水处理(Na+,TNa;Na+/K+比为1 ∶ 1,TNa-K;K+,TK),各处理添加盐分总摩尔量相同,研究灌溉水中不同阳离子组成对土壤盐...

Effect of Saline Water Irrigation with Different Cations Compositions on Lettuce Photosynthesis and Ions Uptake Characteristics

The purpose of this study was to explore the effects of different saline water quality on soil salt properties and crop growth, and to provide scientific basis for saline water irrigation management. A pot experiment was carried out for cropping lettuce in the solar greenhouse. Taking the saturated solution of CaSO₄ as a control (CK), different chlorides were added to deionized water to form three saline water treatments with different cationic compositions (Na⁺, T_Na; Na⁺/K⁺ of 1:1, T_Na-K; K⁺, T_K) on the premise of the same total mole concentration added. The soil salt contents, cations contents, and photosynthetic characteristics, ions uptake and growth of lettuce were studied. The results showed that:(1) At the end of lettuce growing season (80 days after sowing, DAS), the electrical conductivity of saturated extract (EC_e) of soil at 0-20 cm depth was significantly higher than those before sowing and 50 DAS, where CK was significantly lower than others (P<0.05). The differences of soil pH values were not significant among different treatments and depths (P>0.05). At the end of the growth season, the soil salt cations mostly accumulated on the surface layer and were consistent with the salt distribution. (2) Compared with CK, single salt ion stresses (T_Na and T_K treatments) significantly reduced the photosynthetic properties, including net photosynthetic rate, transpiration rate, and stomatal conductance of lettuce (P<0.05), thus resulting in the reduced yield, where the T_Na gave the lowest yield per pot. The photosynthetic properties of T_Na-K were significantly lower than that of CK, but higher than those of T_Na and T_K, indicating that T_Na-K treatment alleviated the harm of single salt ions to the growth of lettuce. And T_Na-K increased yield compared with T_Na and T_K treatment, but without significantly difference (P>0.05). (3) Compared with CK, T_Na and T_K significantly increased the Na⁺ and K⁺ contents in the lettuce leaves, respectively; while the Cl^- content of T_Na-K treatment were higher than CK, but significantly lower than T_Na and T_K (P<0.05). The salt composition with Na⁺/K⁺ of 1:1 in saline water could maintain the ion balance of lettuce plants and alleviate the salt stress of single salt ion on lettuce growth, while as for the single ion stress, Na⁺ should cause the more stress than K⁺.