Effects Of CO₂ Enrichment On Physiological Characteristics,Fruit Quality And Yield Of Tomato In Greenhouse

As one of the main vegetables in human life and diet,tomato has been planted and cultivated in a large area all over the world.Nowadays,with the improvement of people's living standard and agricultural technology,people's demand and standard for daily vegetables are also getting higher and higher.Thus.Facility vegetable began to develop rapidly.Although the investment cost is high,it has the advantages of high yield,high efficiency,energy saving and environmental protection,and it can also liberate the productive forces,making it the only way for agricultural development.Today,greenhouse tomato cultivation technology is becoming more and more mature,but there are also some problems.For example,lighting,temperature,nutrition and other conditions in facility agriculture have been greatly improved.Because the plant growth environment is relatively closed,indoor and external air is difficult to circulate,high density culture and other reasons,resulting in the lack of CO2 concentration in facility.As plant photosynthetic raw materials,CO2 provides carbohydrates and energy for plants.The lack of CO2 will affect the normal growth of plants.CO2 is also widely used as a gas fertilizer in plant cultivation.Therefore,it is very important to study how to improve the CO2 content in facilities and how much CO2 concentration affects plants.In this paper,three different CO2 concentration gradients(treatment A:500?700 ?l·L-1,treatment B:700?900 ?l·L-1,treatment C:900?1000 ?l·L-1)and CK(control without CO2 enrichment:300?400 ?l·L-1)were set up to observe the growth of Tomato under different CO2 concentration,and determine its physiological index,fruit quality and yield,so as to provide physiological basis for actual agricultural cultivation.The experimental results show that:(1)CO2 enrichment significantly promoted plant height and stem diameter of tomato.Plant height increased by 5.62%?16.30%and stem diameter increased by 0.31%?8.71%compared with CK,which was the best treatment for concentration.(2)For tomato photosynthesis,CO2 enrichment can increase net photosy-nthetic rate of tomato,and increase 8.32%?45.63%than CK.Stomatal conductance decreased by 3.33%-28.75%compared with CK,leaf transpiration rate decreased by 4.92%?40.24%,intercellular carbon dioxide concentration increased by 3.24%?39.01%,chlorophyll a content increased by-36.9%?56.84%,chlorophyll b and chlorophyll content decreased by 8.26%?26.12%,1.11%?50.0%,respectively.Starch of tomato leaves is increased by 6.42%?49.95%.(3)For the physiological indexes of tomato,the MDA content of tomato leaves decreased by 42.55%-98.37%compared with CK,Pro content increased by 31.58%?86.76%,SOD content increased by 0%?66.67%,soluble protein content increased by 0.62%?26.98%,total soluble sugar content increased by 3.86%?95.42%compared with CK.(4)The effects of increasing CO2 on fruit quality were as follows:the content of vitamin C increased-6.53%?96.72%,the content of titratable acid decreased by 3.91%?21.21%,the content of soluble sugar increased by 0.53%?33.02%,and the ratio of sugar to acid increased.The soluble solids content increased-1.67%?28.33%.(5)For tomato fruit yield increased obviously with the increase of CO2 concentration.The transverse and longitudinal meridians of fruit increased by 0%?2.87%and 0.23%?1.43%,the weight of fruit per plant increased by 0%?8.85%,the number of tomato fruit per plant increased by 18.52%,and the weight of fruit per plant increased by 14.83%?82.28%,respectively.Tomato yield increased by 14.83%?82.28%.