Research On Soil Water-salt Movement And Photosynthetic Characteristics Of Spring Wheat And Silage Maize With Drip Irrigation

Object: Spring wheat by trickle irrigation in Sinkiang and sequential cropping silage maize is developed form exited cotton region of low production and inefficiency; the most exited low-yield farmland is affected by salt and alkali due to wheat by trickle irrigation and maize are not covered by thin film, and soil evaporation is more intensity; in order to understand influence of soil salinity to movement of water and salt in soil and its photosynthetic physiology indexes of spring wheat by trickle irrigation and sequential cropping silage maize, and provide theoretical foundation and technical support for spring wheat by trickle irrigation and sequential cropping silage maize planting in saline and alkaline land.Methods: Select spring wheat variety “xinchun 6” and silage corn variety “ruiyu F98” as the research object, pot experiment design non-soil salinization, soil salinization mild, moderate soil salinization, strength saline soil total five different soil salt content processing, monitoring changes in spring wheat and silage corn movement of soil water and salt as well as its photosynthetic characteristics, growth indices, yield and other indicators.Results: 1. Soil moisture content and salt content of spring wheat by trickle irrigation and sequential cropping silage maize in reproductive period have good synchronicity; with increase of soil depth（0⁴0cm）, soil moisture content and salt content present an increasing tendency. The more soil salt contents and soil water storage are, the better the desalting effect looks. In reproductive period of spring wheat, non-saline salt deposition accounts for 18.89%; mild evolution processing desalination accounts for 22.15%; moderate evolution processing desalination accounts for 39.23%; severe evolution processing desalination accounts for 41.68%; saline soil processing desalination accounts for 44.08%; in reproductive period of silage maize, non-saline salt deposition accounts for 11.06%; mild evolution processing desalination accounts for 12.93%; moderate evolution processing desalination accounts for 16.92%; severe evolution processing desalination accounts for 25.68%; saline soil processing desalination accounts for 30.83%.2. Daily variation trend of net photosynthetic rate for leaves of spring wheat presents bimodal type; phenomenon of photosynthetic “midday rest” is obvious; daily variation trend of transpiration rate presents single-peak type; daily change rule of stomatal conductance and net photosynthesis is similar; intercellular concentration of CO2 roughly presents decline in the morning and rise in the afternoon; concurrence of stoma and non-stoma factors limits photosynthesis of leaves of spring wheat; decline of net photosynthetic rate is mainly caused by stoma factor under soil treatment of low salinity, and non-stoma factor under soil treatment of high salinity. Daily variation trend of net photosynthetic rate for leaves of silage maize presents single-peak type; phenomenon of photosynthetic “midday rest” does not appear; daily variation trend of transpiration rate presents single-peak type; daily change rule of stomatal conductance presents single valley type; intercellular concentration of CO2 roughly presents decline in the morning and rise in the afternoon; photosynthesis for leaves of silage maize is limited by stoma factor; decline of net photosynthetic rate is mainly caused by stoma factor under soil treatment of low salinity, and jointly by stoma and non-stoma factor under soil treatment of high salinity.3. Growth curve of plant height of spring wheat by trickle irrigation and sequential cropping silage maize roughly presents “S” shape; change curve of leaf area per plant present trend of first rise and then drop. In whole growing period, when salt content of soil is lower, it has a little influence on plant height and leaf area per plant of spring wheat and silage maize; when salt content of soil is higher, it restrains growth of plant height and leaf area per plant. Salt content of soil has a great influence on yield index of spring wheat by trickle irrigation and silage maize; yield index and salt content of soil shows a negative relationship.4. According to production functional model of sectional type of crop salt, production function of salt of spring wheat by trickle irrigation and sequential cropping silage maize are respectively: Y_r = 1- 0.03129（ S- 6.46021）;Y_r = 1- 0.02177（ S- 5.24483）. Determine that critical value of salinity tolerance of spring wheat by trickle irrigation is S_t = 6.46g/kg; threshold value of salinity tolerance is S_10% = 9.63g/kg; critical value of salinity tolerance of sequential cropping silage maize is S_t = 5.24g/kg; threshold value of salinity tolerance is S_10% = 9.78g/kg.Conclusion: Spring wheat and sequential cropping silage maize by trickle irrigation can normally grow under non-saline soil（salinity content ≤3 g/kg） and light saline soil（salinity content≤6 g/kg）; they will reduce about 10% for planting on moderate saline soil（salinity content≤10 g/kg）; their growth will be seriously restrained for planting on severe saline soil（salinity content≤20g/kg）; only several plants can survive or no one can survive for planting on saline soil（salinity content>20g/kg）.