| The temperature was one of the main factors to limit the distribution of vegetable plant. Enhance along with the world green-house, Protected horticulture for producing air temperature could been often reached above 40℃, the air temperature of open field also often reached above 35℃in summer and autumn(Du Yun-chen,1996). Salicylic acid(SA),was regarded as a new plant hormone.(Malamy.1990)The researches had showed: Salicylic acid(SA)had effect on plant photosynthesis, the seed germination(Yuan Yongbing,1994), anti-heat(Dat etal.,1998). Anti-heat of plant could been increased by spraying SA on the muster seedlings at the first(Dat etal.,1998), grape seedlings(Wang Li-jun,2001). But the reports that SA could been increased the ability to anti-heat on cucumber seedlings were very rare. Therefore, Cucumber seed and seedlings were used as research material in this paper. The effects of seed germination and seedlings growth were studied by spraying different concentration SA under the different temperature. There were some results; 1 Germination rate of cucumber seeds went down successively along with the temperature up. 30 ℃was the most suitable temperature of cucumber seed germination. 2 Some indexes successively went down with the temperature up , such as the root of embryo, the fresh weigh of embryo bud, vigor indexes ,they reached the maximum at 30℃. 3 The POD activity of root and bud successively went down with the temperature up. The POD activity reached the maximum at 30℃. 4 The Fo and NPQ of grafted and own-rooted seedlings successively went up with the stress temperature up. At the different treatment periods and under the condition of green-house, The Fo and NPQ went up with treatment going on. At the differ treatment periods and at 40℃/30℃, The Fo and NPQ of grafted and own-rooted seedlings were in accordance with CK. the enhance extent of grafted seedlings was lower than own-rooted seedlings. 5 The Fv/Fm, ?PSⅡ, qP and Fv,/Fm, of grafted and own-rooted seedlings went down with the stress temperature up .At the different periods and under the condition of green-house;the Fv/Fm, ?PSⅡ, qP and Fv,/Fm, went down with the treatment period going on;At the different period and at stress-temperature of 40℃/30℃, the change tendency was in accordance with CK ; the lowering extent of grafted seedlings was lower than own-rooted seedlings. 6 The Pn, CE, AQY of grafted and own-rooted seedlings successively went down with the temperature up, and they had the maximum30℃/20℃. 7 The contents of Chla, Chlb, Chla+Chlb, Chla/Chlb and Caro, the activity of POD grafted seedlings and own-rooted seedlings went down with stress temperature up. The lowering extent of grafted seedlings was lower than own-rooted seedlings. 8 The contents of MDA and Pro in grafted and own-rooted seedlings went up with stress temperature up. The enhance extent of grafted seedlings was lower than own-rooted seedlings. 9 The plant height, vigor index ,dry material contents of ground, the ratio of root-top went down with the stress temperature up. The lowering extent of grafted seedlings was smaller than own-rooted seedlings. 10 Under the stress temperature, the change tendency of seed germination and seedlings were in accordance with CK, after spraying SA. But the change extent was obviously poorer than CK. The low concentration SA(0.05mmolL-1)had small effect on seed germination and seedlings ,but the high concentration SA(0.5mmolL-1)had different restrain on seed germination and seedlings. The best concentration of SA was 0.1 mmolL-1 11 The ability to anti-high temperature of grafted seedlings was superior to own-rooted seedlings. The most suitable concentration of SA to cucumber seedlings was 0.1 mmolL-1... |
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