Effects Of Sub-low Temperature And Potassium Fertilizer On Ecophysiological Characteristics And Nutrient Absorption Of Greenhouse Tomato

The test uses facility tomatoes （Lycopersicon esculentum）,cultivars"Jinpeng No.10",astest material, by a pot experiment, from November2011to April2012in solar greenhouse inthe Northwest A＆F University, Yangling, Shaanxi, we study the effects on the plant heightstem diameter, leaf area, leaf water potential, chlorophyll content, net photosynthetic rate （P_n）,stomatal conductance （G_s）, transpiration rate （T_r）, intercelluar CO₂concentration （C_i）,stomatal limitation value （L_s）, water use efficiency （WUE）, dry matter accumulation anddistribution of N, P and K absorption and utilization, yield and quality of the the tomatoes ofthe greenhouse potted plants under the interaction of the sub-low temperature and thepotassium fertilizer. The main findings are as follows:1. Under the sub-low temperature, the plant height, stem diameter, area of leaves, the leafrelative water content, leaf water potential, the first inflorescence for number of flowers, thefirst inflorescence spend the next number of leaves and the average section spacing of thetomato plants reduced, and was clearly lower than normal temperature. Under the normaltemperature, the suitable potassium fertilizer application rates can promote the natural growthof tomatoes, while under the sub-low temperature, increase the potassium fertilizer properlycan promote the growth and development of the tomato plants. However, under the interactionof the sub-low temperature and the potassium fertilizer, it has tint effects on the firstone-inflorescence for number of flowers; After adding potassium fertilizer, its’ plant height,stem diameter, blades area increased, all these indicating that enough potassium fertilizer canease the inhibitory effect of the sub-low temperature and even the low-temperature brought;tomato plants leaf relative water content to the changes in trends and the leaf water potentialwas positively correlated, to say under the sub-low temperature of, the absorptive capacity ofof the root to water weakened, while the of additional potassium fertilizer can improve the itsleaf water content.2. Compared with the normal temperature,tomato leaf chlorophyll a, b and chlorophyll （a+b） content reduced significantly under sub-low temperature, and when the content ofchlorophyll a increased, chlorophyll a/b ratio reduced.On the basis of sub-low temperature,adding a certain amount of potassium fertilizer （SD） is good for improving tomato plants’chlorophyll content, too little or excess is not conducive to the normal metabolism of leaf chlorophyll. Sub-low temperature reduced the net photosynthetic rate （P_n） of the tomatoleaves significantly, When the application amount of potassium fertilizer is the0^-18.54g perplant, the blade P_nincreased gradually, the application amount of potassium fertilizer is the24.72g per plant, it even reduced; stomatal conductance （G_s）, intercellular CO₂concentration（C_i） and transpiration rate （T_r） variation of net photosynthetic rate （P_n） is broadly consistent;but stomatal limitation value （L_s） and G_s was negatively correlated with the variation, atnormal temperature, L_sis in general less than stomatal limitation under sub-low temperature,and sub-low temperature stomatal limitation is more significant; for tomato leaf water useefficiency （WUE） at normal temperature, tomato leaf WUE was significantly higher thansub-low temperature, but there is no obvious pattern between K treatments, the difference wasnot significant.3. Compared with the normal temperature, sub-low temperature stopped the root, stem,leaf biomass yield, and total biomass yield of the tomatoes. Either at normal temperature orsub-low temperature, from the tomato plant dry weight allocation point of view, the root, stem,leaf distribution rate has significant differences （P <0.05）, and its accumulation: leaf> stem>root. Under sub-low temperature, with the levels of potassium fertilizer increased, roots,stems, leaves and biological yield of whole plants showed an increasing trend, in which theroot dry matter accumulation greater impact. Either at normal temperature or sub-lowtemperature, one of the notable features of tomato plants total nitrogen （N）, phosphorus （P）,potassium （K） of nutrient contents in leaf nitrogen content exceeds the concentration ofphosphorus and potassium, where N: leaf> stem> root, P: leaf> root> stem,K: leaf> stem>root. In various periods of tomato plants, leaf nitrogen content is higher than the content of theroots and stems, roots the lowest nitrogen content.4. Compared with the normal temperature, sub-low temperature reduced the averageweight of the the first spike fruits of the tomato plants, and fruit Vc, soluble protein, solublesolids, soluble sugar content, but organic acid content increased. Adding a certain amount ofpotassium fertilizer （18.54g per plant） can improve the first spike fruit weight, fruit Vc,soluble protein, soluble sugar content, improved fruit quality, more or less is not conducive tothe growth and development of the fruit, even affecting the flavor and quality of the fruit.In short, under normal temperature, suitable amount of potassium fertilizer can promotethe tomatoes normal growth and development, improve photosynthesis, fruit weight, fruitquality, but excessive potassium fertilizer will restrict the growth. Under sub-low temperature,the temperature stress will decline the cold resistance of tomato plants, growth retardation,while the interaction of sub-low temperature and potassium fertilizer improved the growth, asthe potassium fertilizer increased, the growth and development of tomato plants promoted, and alleviated the damage caused by stress. The test results show that in sub-low temperature,the amount of potassium fertilizer per plant18.54g （SD） of tomato plants by the sub-lowtemperature stress relieving better, less potassium fertilizer or dorsch not conducive to thenormal growth and development of tomato plants under sub-low temperature. It suggestedthat adding a certain amount of potassium fertilizer can increase tomato resistance undersub-low temperature. it is conducive to the growth and fruit yield of tomato plants, andimprove the quality.