| Rice is the first of three major grain crops, more than half of our population rice is the staple food, its production directly affect national food security. Our rice-growing areas are located in the humid and rainy region, submergence situation is grim.When rice suffered submergence stress, the plant respiration limited, made it in a hypoxic state, And less light plant,low photosynthetic rate, reduce the nutrient supply and the accumulation of large amounts of toxic substances, seriously affect the normal growth and development of rice, and even lead to death. Submergence stress is one of the main stress factors of rice growth, how to take effective and feasible way to improve drought resistance in rice has become an urgent problem in production southern China. This article in Resources and Environment, Guangdong Academy of Agricultural Sciences net room in Guangzhou city, rice submergence test was carried out by pot experiment, were studied under the pre-disaster and post-disaster spraying spraying in two ways, 6 kinds of different organic carbon/nitrogen nutrition include Proline(Pro), L-Threonine(Thr), L-Arginine(Arg), Glycine(Gly),Choline chloride(CC), Mannitol(Mnt), the study research the influences on rice physiological indexes, resistance index, root activity index and iutrition indicators when its suffered submergence stress during the early panicle initiation, by analyzing and comparing the time and select the appropriate spray suitable organic carbon/nitrogen nutrients. The concluded as follow:1 The impact of the rice physiological indices on organic carbon/nitrogen nutritionCompare with not spraying nitrogen, spraying of different organic carbon/nitrogen can effectively increased leaf chlorophyll content after the relief of submergence, and improve photosynthetic rate, made the rice plant physiological processes faster recovery. In 6 kinds of organic carbon/nitrogen nutrition, Thr, Arg,Pro, Mnt and CC have greater impact on leaf photosynthetic rate(Pn value). Arg,CC,Thr and Mnt have greater impact on leaf SPAD values. Among them, the results show that Arg,Thr and CC can better and fast recovery the leaf chlorophyll content and photosynthetic rate after rice submergence stress. This is due to Arg has a nitrogen storage function, also is the precursors of biologically active messenger molecules PA and NO, have great regulation effect on Chlorophyll and photosynthesis after rice submergence stress. CC can improve the content of chlorophyll, enhance chloroplast Hill reaction activity, promote photosynthetic electron transfer and improve some key enzyme activity. Mnt have great recovery effect on rice photosynthesis after submergence stress, but no relevant reports at now,this needs to be further study.2 The impact of the rice stress tolerance index on organic carbon/nitrogen nutritionWhen suffered the submergence stress, rice antioxidase, such as superoxide dismutase(SOD), Peroxidase(POD), Catalase(CAT) activity Reduced, The content of Malondialdehyde(MDA) increased, and Proline(Pro) accumulation. This study concluded that pre-disaster and post-disaster spraying in two ways, 6 kinds of different organic carbon/nitrogen nutrition have same effect on rice resistance,that is SOD, POD, CAT activity gradually increased and then gradually stabilized after removed the submergence stress. MDA content increase first, then gradually reduced to normal levels. Pro content showed a growing trend. Compared with not spraying nitrogen, spraying of 6 kinds of organic carbon/nitrogen can certainly increase the rice sesistance ability, which have better resilience effect are Mnt, Arg and Pro. This may be due to the Mnt concentration(200mg/kg) used in the test quite high, can reduce turgor, the nutrient and moisture absorption is blocked, nutritional consume reduced, cell senescence stayed, Make antioxidant enzymes SOD activity improved and the rice resistance enhanced. Arg and its metabolite polyamines(PA) can as a signal substance to stimulate cell growth, at the same time can activate plant defense genes and hypersensitivity by the reactive oxygen species to improve the rice disease resistance under submergence, thereby can improve the anti-submergence stress capability. Pro is one of the plant protein constituent, it can serve to maintain s Tab. cell under stress, reduce the role of cell damage, it have good effect to rice when its under submergence stress.3 The impact of the rice Root resilience index on organic carbon/nitrogen nutritionThe root alcohol dehydrogenase(ADH) activity were improved when the rice under submergence stress. On the one hand due to root ADH can converte acetaldehyde which is harmful Substance to ethanol, simultaneously provide little ATP. On the other hand, it can prolong the survival time of rice by pasteur effect to maintain high energy charge. In two cases that organic carbon/nitrogen nutrition pre-disaster and post-disaster spraying, rice root ADH activity were higher than not spraying after the lifting of submergence stress, that directions organic carbon/nitrogen nutrition have a good effect on increase root resilience, among them, Pro, Thr, Arg and CC the effect is obviously. Related to the above 4 kinds of organic carbon/nitrogen nutrition to root system ADH activity is no relevant reports so far, We guess probably because these organic carbon/nitrogen nutrition could improve the anti-submergence Stress ability of the rice aboveground part, thereby it can reduce energy consumption on root, there may be another reason is that its stimulate the root ADH genome expression, these needs to be follow-up in-depth study.4 The impact of the rice plant stress indicators on organic carbon/nitrogen nutritionCompare with not spraying nitrogen, spraying of different organic carbon/nitrogen can Increase rice plant NPK content effectively after lifting submergence stress. In 6 kinds of organic carbon/nitrogen nutrition, Gly, Arg, Thr and Pro have greater impact on rice plant total nitrogen content. Mnt, Pro, NA, Thr and CC have greater impact on rice plant total phosphorus content. Thr, Gly, Arg, Mnt and Pro have greater impact on rice plant total potassium content. The research shows that rice under submergence, whether pre-disaster or post-disaster, could both increase rice plants NPK content, increase the accumulation of nutrients, reflecting the it could improve the ability of rice anti-submergence.5 The influences of two kinds of spraying mode to rice stress tolerance indexSpraying organic carbon/nitrogen nutrition before rice submergence, principal component analysis on each processing stress tolerance index, root stress tolerance index and nutrition indicators in 6 days after rescission of submergence, inferred that the ability of resilience of 6 kinds of organic carbon/nitrogen nutrition as followed, Arg>CC>Mnt>Thr>Gly>Pro, among them, Arg, CC, Mnt, Thr and Gly has good effect to lifting submergence stress. Spraying organic carbon/nitrogen nutrition after rice submergence, principal component analysis on each processing stress tolerance index, root stress tolerance index and nutrition indicators in 6 days after rescission of submergence, inferred that the ability of resilience of 6 kinds of organic carbon/nitrogen nutrition as followed, Arg>Thr>Gly>Pro>Mnt >CC, among them, Arg, Thr, Gly, Pro and Mnt has good effect to lifting submergence stress. |
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