| Low temperature stress frequent occurred in Jilin province which has resulted insubstantial drop in rice production for seven times in our history. At present, famers generallyuse less nitrogen but more phosphate and spray water and phosphate in production to defenselow temperature, but the inner mechanism concerning the process has rarely been reported.Therefore, the study takes cold tolerance rice varieties Japonica81and Changbai9as studyobjects; simulates low temperature condition in rice transplanting and booting periods anddesigns corresponding phosphate fertilizer gradient through artificial climate facilities;analyzes the physiology and yield of the two rice varieties under different degrees of lowtemperature and phosphate ranges, determines optimal phosphate range in different growthperiods under low temperature. The main results are as follows:I．Low temperature in transplanting period will affect the growth of Japonica81andChangbai9seedlings and lead to the reduction of the maximum number of tillers, delay of themaximum tiller time and slower speed of new leaves growth. However, if adding appropriateamount of phosphate fertilizer in the bed soil under low temperature, the maximum number oftillers improve19.7%and27.4%, new leaves improve8.55%and10.7%, the maximumtillering time reduce2.7d and3.9d, expansion rate of stalk in maturity shorten9.15and10.40%. Seedling mortality of Jijing81change less than Changbai9, low temperatureresistance level of Changbai9is from3level to1level. The result show that soil increasedphosphate fertilizer can improve cold tolerance ability in northeast japonica rice.II．Low temperature in booting stage results in decline in seed setting rate, mature plantheight and headings of Jijing81and Changbai9. However, adding phosphate fertilizer in thebasal, mature plant heigh of two varieties increase12.4%and15.4%, headings increase0.77times and6.63times, seed setting rate of Jijing81is range from72.3~88.0%, low temperatureresistance level is from3level to1level, but seed setting rate of Changbai9is range from52.3~78.3%, low temperature resistance level of is from5level to3level, The result showthat increased phosphate fertilizer can improve cold tolerance ability in northeast japonicarice. Ⅲ. Net photosynthetic rate of two varieties decrease79.5%and69.8%in transplantstage under low temperature, and in booting stage they decrease12.8%and19.4%.Fluorescence dynamic analysis shows that Fv/Fm decrease by adding phosphate fertilizer. ForJijing81, qP in crease and NPQ decrease, when phosphate fertilizer application is120kg/hm~2,qP reach maximum(0.70)and NPQ reach minimum(0.37). the reasults show that cold resistantvarieties of Jijing81can use higher NPQ to dissipate. For Changbai9,qP and NPQ increase,when phosphate fertilizer application is120kg/hm~2, it reach maximum. The reasults showthat Changbai9can use higher qP to reduce reflect the center of damag.but NPQ is increase,so increaseing phosphate fertilizer application can increase the radiation heat dissipation ofenergy, reduce the damage of low temperature stress, improve the northeast japonica rice coldtolerance ability.Ⅳ. Under the low temperature, increasing phosphate fertilizer application，membranepermeability and MDA decreased，but soluble sugar content，proline, peroxidase(POD),catalase(CAT) and superoxide dismutase (SOD) increased. Compared with Jijing81, PODactivity in Changbai9is increased higher when applying more P. The activity of POD, CATand SOD are increased38.2%,39.7%and98.9%accordingly. The results indicate thatappropriate increase the amount of fertilizer P will enhance membrane permeability of leavesand the activity of POD, so that increase the cold disaster resistance of Japonica rice innortheast China.Ⅴ. The low temperature in transplanting period causes output decrease of Japonica81and Changbai9in many aspects such as secondary branch number, ear length, panicles perhole, grains per panicle and grain weight, among which the influential order follows as grainsper panicle> panicles per hole>grain weight. However, after adding Phosphate fertilizer inthe bed soil, the above mentioned factors improve greatly for the two varieties. The lowtemperature in booting stage causes decrease of Japonica81and Changbai9in many aspectssuch as secondary branch number, ear length, panicles per hole, grains per panicle and grainweight. But different from the influential factors orders in transplanting period, the order inbooting stage follows as grains per panicle> grain weight> panicles per hole. However, afteradding phosphate fertilizer in the bed soil in booting stage, the above mentioned factors improve greatly for both varieties and phosphates exert more effects on non-chilling tolerantvarieties.Ⅵ. Under low temperature condition, phosphate can increase the brown rice rate, milledrice rate, chalkiness, the fatty acid content and the straight-chain starch content of the two ricevarieties. It can also lower chalky grain rate and protein content. According to related analysis,the quality indicators are not closely related to phosphate levels under normal temperaturecondition. However, under low temperature condition, the high milled rice rate of Japonica81reflects its significant positive correlation with phosphate level. As to Changbai9, its brownrice rate, milled rice rate and complete milled rice rate are all in high positive correlation tophosphate level. In contrast, the protein content of both rice varieties are negatively related tophosphate amount but the fatty acid content is significantly positively related to Phosphatefertilizer amount. Other quality indicators are not significantly related to phosphate.Ⅶ. Considering the yield and other influential factors, the optimal phosphates in bed soilranges for Japonica81and Changbai9are respectively61.69g/m~2~71.18g/m~2and60.35g/m~2~68.02g/m~2. It can reduce effect of the growing process in rice under lowtemperature stress. The optimal basic phosphate manure ranges respectively from103.65kg/hm~2~120.44kg/hm~2to91.85kg/hm~2~114.73kg/hm~2. It can improve cold toleranceability. |
PDF Full Text Request