Effects Of Low Temperature And Poor Light Stress On Photosynthetic And Senescence Characteristics Of Greenhouse Tomato

In recent years, the facility agriculture has developed rapidly in our country, has become the main direction of agriculture in our country. Low temperature and poor light compound disaster is one of the main meteorological disasters in facility agriculture in winter, how to prevent low temperature and poor light compound disasters of facilities for agricultural development effectively at present stage is the key problem to be solved. Tomato (Lycopersicon eseulentum) is the main facility crops, planting area and yield are the first in our country. Low temperature and poor light compound disaster has a serious impact to greenhouse tomato growth. To research the influence of the low temperature and poor light compound disasters on the physiological characteristics of tomato growth in flowering stage, taking tomato variety of ’Jinfen 5’ as material, the artificial environment control experiment of low temperature and poor light was conducted in Nanjing University of Information Science and Technology. The daily temperature/ night temperature was treated as four levels: 18/8℃,16/6℃,14/4℃ and 12/2℃, photosynthetically active radiation(PAR) was set two levels :400μmol m-2 s-1 and 200μmol m-2 s-1, took daily temperature/night temperature 28/18℃ and PAR 1000μmol·m-2·s-1 as control(CK).The results are as follows:(1)The results showed that with the decrease of LT and LI and the increase of processing days, PN, gs and Ls presented a declining trend,By comparing Rectangular hyperbola model,Non-rectangular hyperbola model and Exponential model to choose the most suitable model to simulate the light response curve, the changes of photosynthetic parameters were as follows: LSP and Pmax showed a declining trend, while LCP showed a opposite trend. Fv/Fm, ETR and P had varying degrees of decline, but qN, D and E showed a rising trend. The Chla, Chlb content and Chl(a/b) presented a declining trend, Chl(a/b) changed a little among them, while SOD, POD, CAT activity, MDA content and relative conductivity of tomato leaves showed a opposite trend.(2)The more serious the low temperature and low light stress, the longer the treat time, the tomato needed more time to return to the CK level. The experiment treated 8 and 10 days at daily temperature/night temperature was 12/2℃, PAR was 400μmol m-2·s-1 and 200μmol·m-2·s-1 recovered for 21 days,the tomato did not return to the CK level.(3)Through the ranking of composite scores of every treatments by principal component analysis, the result showed that when at the same poor light level, the lower the temperature, while at the same low temperature level, the lower the PAR,the greater damage degree of tomato photosystem. Under low temperature and poor light stress, the damage to the tomato treated under 14℃ and 12℃ is more serious than that under 18℃ and 16℃; The damage of temperature reduced 2℃ to the facilities tomato is more serious than the damage of PAR reduced from 400μmol m2·s-1 to 200μmol℉m-2·s-1. The study could provide facilities for tomato low temperature disaster warning and defense to provide the scientific basis.