Study On The Irrigation Regime And Water-Fertilizer Coupling Of Tomato In Solar Greenhouse

This paper studied the irrigation regime and water-fertilizer coupling of tomato in solar greenhouse in condition of drip irrigation under film, and formed an optimal irrigation and fertilization system taking account into tomato yield, quality, plant morphology, photosynthesis, water use efficiency and soil nutrition content comprehensively. Focusing on the irrigation regime, this paper summarized the water consumption regularity and established the water production function by pot cultivation and drip irrigation under film. By monitoring the morphological index, quality index, photosynthetic index and yield index, a comprehensive evaluation of tomato yield, water use efficiency and quality is made to get a suitable irrigation regime of tomato in solar greenhouse. Focusing on the scheme design of water-fertilizer coupling, adopting model of double line planting at one width ridge combined with drip irrigation under film, this paper studied the tomato yield and fertilizer use efficiency, and established the optimal water-fertilizer management pattern by monitoring the meteorological index and soil index. The main conclusions were as follows:(1) By analyzing the growth morphology indexes of tomato, it can be seen that, it is beneficial to the growth of plant height, stem diameter, leaf area in seedling stage, when soil water rate is controlled within 70%～75% of field capacity; In flowering stage, an appropriate water deficit contributes to the growth of plant stem diameter, and it’s beneficial when soil water rate is controlled within 60%～65% of field capacity, while it’s more beneficial to the growth of plant height and leaf area when soil water rate is controlled within 75%～80% of field capacity; In fruiting stage, it is beneficial to the growth of tomato plant height, stem diameter, leaf area when soil water rate is controlled within 80%～85% of field capacity; In later fruiting stage, the tomato plant almost stops growing.(2) By analyzing the the quality index of tomato, different water treatments have significant impacts on the content of soluble sugar, vitamin C, organic acid, sugar-acid ratio, but no significant impacts on the content of soluble protein. When soil water rate is controlled within 70%～75%、60%～65%、80%～85%、75%～80% of field capacity respectively in different developing stages, the content of soluble sugar is up to 16.71%, content of vitamin C is up to 16.91mg/g, the sugar-acid ratio is up to 39.79, which are all the highest value; While soil water rate is controlled within 70%～75%、75%～80%、80%～85%、60%～65% of field capacity respectively in different developing stages, the content of soluble protein is up to 0.053mg/g, and content of organic acid is up to 0.57%, which are both the highest value. It shows that in flowering stage, appropriate moisture deficit helps the accumulation soluble sugar, vitamin C and sugar-acid ratio; In later fruiting stage, appropriate moisture deficit helps the accumulation of soluble protein.(3) The analyzing result of the tomato photosynthetic indexes shows that the difference of stomatal conductance under different treatments in flowering stage is not significant, and content of soil moisture does not have much effect on stomatal conductance. When soil water rate is controlled within 60%～65% of field capacity in fruiting stage, it contributes to the improvement of stomatal conductance; In flowering stage as well as fruiting stage, content of soil moisture both has significant effect on net photosynthetic rate under different treatments, when soil water rate is controlled within 75%～80% of field capacity, it helps improve net photosynthetic rate in flowering stage, while it helps improve on net photosynthetic rate of tomato plant when soil water rate is controlled within 80%～85% of field capacity in fruiting stage.(4) This paper made a comprehensive evaluation of tomato yield, water use efficiency and quality under small tube irrigation by using principal component analysis method, and got an optimal irrigation regime for tomato in solar greenhouse during the whole developing stage: In seedling stage, infuse water 2 times, irrigation quota is 15～16 mm; In flowering and fruiting stage, infuse water 3 times, irrigation quota is 15～17mm; In full fruit-bearing stage, infuse water 5 times, irrigation quota is 15～17 mm; In the late period of fruit-bearing stage, infuse water 4 times, irrigation quota is 10～13mm. The total irrigation quota is 190-220 mm during the whole developing stage.(5) By analyzing the moisture sensitivity index of tomato in solar greenhouse, this paper established the water production function of Jensen model, Minhas model, Stewart model and Singh model. It shows that the fitting degree of Jensen model is far higher than other models. The moisture sensitivity index of tomato in solar greenhouse in seedling stage, flowering stage, fruting stage, and later fruiting stage are 0.015,0.218,0.509 and 0.036 respectively. The dehydrated traits in each stage is not the same as well, and as a result, tomato in fruting stage is most sensitive to water deficit degree, and tomato in flowering stage comes second, which demonstrates that growth of tomato plant is also sensitive to water deficit degree, and tomato in seedling stage is least sensitive to water deficit degree.(6) Under the combination of nitrogen fertilizer, phosphate fertilizer, potash fertilizer are 565 kg/hm2,375 kg/hm2,150kg/hm2 respectively, and irrigation quota is 200 kg/hm2, the tomato yield is largest, which may be higher than 50000 kg/hm2.(7) Similarities can be found in soil volumetric moisture content variation trend under different water treatments. As time goes on, the soil moisture content under different water treatments are on the decline. The temperature of solar greenhouse and the content of soil moisture have close correlation with tomato growth environment and affect it directly, therefor we should focus on these two factors.(8) The spatial distribution of available nitrogen is regularly among the different water fertilizer coupling treatments, with an overall 45 degrees slash distribution, the residues of available nitrogen in soil depends on the application amount of nitrogen, with a positive correlation; There is a similar trend in 0～60cm to maintain available phosphorus residues, but with the soil deeper, content of phosphorus is improved with no regular distribution; From the residual distribution of potassium content, it can be seen that the distribution in space on the overall presentation is an "S" type, a smaller difference between treatments, and there is a regularity of basic agreement.