Response Of Tomato And Spinach Growth To Salt Stress And Nitrogen

The greenhouse and indoor experiments of vegetable were conducted and to study the response of tomato and spinach growth to salinity and nitrogen while the salt increasing. In greenhouse, the experiment has 3 salt treat: control (0.87 dS m^-1, S0), 2dS m^-1 (S1) or 5dS m^-1(S2), and the try crop is tomato. The indoor exper iment has the same salinity treatments. However, it contains 2 nitrogen level: 100 kg N ha^-1 (N1) and 300 kg N ha^-1 (N2) , and the try crop is spinach. The results indicate,(1) At the end of tomato growth, treatment S1 inhabits the leaf area and treatment S2 help tomato to increase leaf area, but the increment of leaf area is at the expense of tomato yield. At the end of spinach growth, salinity has significant effect on the leaf area, at the same time the leaf area of treatment S1 is more than that of treatment SO; however, that of treatment S2 is less. At the level of 100 kg N ha^-1, treatment S1 promotes the dry matter weight, and treatment S2 inhabit the dry matter weight; at the level of 300 kg N ha^-1, increasing with the salinity, the dry matter weight of spinach decrease.(2) Increasing with the salinity, the yield of tomato decreases, because of the adverse effect of salinity on the fruit weight. At the low nitrogen level, treatment S1 can benefit spinach growth and increase yield; at the high nitrogen level, salinity hold back crop growth and yield.(3) Under salt condition in 2.0 and 5.0 dS m-1, the root: shoot ratio increase with the days after sowing in "S" curve. The increase in root: shoot ratio came from an allometric growth between root and shoot, which could be expressed by the following equation: y = a + bx .Where y is the natural logarithm of root dry weight, x is the natural logarithm of shoot dry weight. Effect of salt stress on b value is dissimilar at different nitrogen level. Salt in 2 dS m^-1 can increase b value at 100 kg N ha^-1 level, which means the growth of root and shoot is harmonious, so yield of spinach increase. However, at 300 kg N ha^-1 level, b value of salt in 5 dS m^-1 which is 1.34, is higher than that of control.(4) The effect of salinity on the cumulative ET of tomato is not significant; at the end of spinach growth, the effect of salinity on the cumulative ET is significant. At the 100 kg N ha^-1 level, every day consumed soil water of 3 treatments of salt are 5.2 mm, 5.6 mm or 5.0mm, respectively; at the 300 kg N ha^-1 level, they are 5.8mn, 5.7 mm or 5.0mm.(5) The nitrogen take-up of spinach is significant quadratic correlation with the days of sowing at different salinity and nitrogen level. The effect of salinity and nitrogen on the content of NO3-N and NH4-N is different in different days after sowing and soil depth. Higher nitrogen fertilizer can increase NO₃-N and NH₄-N content of soil profile.(6) Salinity can decrease the tomato's WUE_F. Under salt condition, treatment N2 can increase the spinach's WUE by 9.6%; the maximum of WUE is 25.8 kg m^-3 in treatment N2S0. In comparison with treatments of N1, those of N2 decrease NUE by 40%; moreover, salinity increasing promotes NUE decreasing. At higher level of salinity and nitrogen, NRE and NAE are least and residualnitrogen is most, so the potential danger to environment is most serious.(7) Chloride ion most distribute up 10cm of soil profile 33 days after spinach sowing; Cl^- transport to 50 cm of soil profile at the end of spinach growth. The effect of nitrogen on the Cl" distribution is not significant. Soil ECe is the quadratic function of inorganic nitrogen content before 33 days after sowing; since 33 days the ECe is the linear equation of Cl" content.