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1、灌漿初期高溫影響水稻籽粒充實和劍葉理化特性摘要：為探明灌漿初期高溫熱害降低水稻籽粒充實度的可能生理原因，本文以遺傳背景相近而灌漿期耐熱性存在顯著差異的2個水稻純系XN0437T（耐熱）和XN0437S（熱敏感）為材料，于水稻抽穗后第10天進行高溫處理，調(diào)查了水稻籽粒充實度，測定了與水稻劍葉光合效率、細胞膜透性和滲透調(diào)節(jié)有關(guān)的生理指標。結(jié)果表明，高溫處理后水稻籽粒充實度、葉綠素含量、劍葉的凈光合速率和可溶性糖含量降低，熱敏感純系的下降幅度大于耐熱純系；超氧化物歧化酶（SOD）活性、細胞膜透性、丙二醛（MDA）和脯氨酸（Pro）含量
2、增加，其中熱敏感純系的MDA含量、細胞膜透性增加幅度大于耐熱純系，而其SOD活性、脯氨酸含量的增加幅度小于耐熱純系。灌漿初期高溫抑制水稻劍葉光合效率，增加細胞膜透性和改變細胞內(nèi)環(huán)境是高溫熱害降低水稻籽粒充實度的生理原因。關(guān)鍵詞:水稻;高溫;籽粒充實度;理化特性Effectsofhightemperatureonricegrain-fillingofcaryopsisandphysiologicalbiochemicalcharacteristicofflagleaveatearlymilkystageofriceTheaimof
3、thisexperimentwastoascertainpossiblephysiologicalcausesofhightemperaturedecreasinggrain-fillingrateatearlymilkystageofrice.Tworiceinbredlines,namedXN0437T(heat-sensitive)andXN0437S(heat-tolerant),wereselectedandtreatedbyhightemperatureatthe10thdayafterheading.Thegrai
4、nplumpnessrate,indexesrelatedtophotosyntheticefficiency,cellmembranepermeabilityandosmoticadjustmentinflagleavesweredetectedinricelinesXN0437TandXN0437S.TheresultshowedthatthegrainplumpnessratewasreducedunderhightemperatureinbothXN0437TandXN0437Sandthereducedrangeofh
5、eat-sensitivelinewasgreaterthanthatofheat-tolerantline.Thenetphotosyntheticrate,chlorophyllcontentandsolublesugarcontentweredecreasedincomparisonwithcontrolbothinheat-sensitiveandheat-tolerantricelines,andthedecreaserangeofthesephysiologicalmattercontentsweregreateri
6、ntheheat-sensitivelinethanthatoftheheat-tolerantline.Thesuperoxidedismutase(SOD)activity,malonaldehyde(MDA)content,cellmembranepermeabilityandproline(Pro)contentwereincreasedunderhightemperature,andtheincreasedrangeofMDAcontentandmembranepermeabilityinheat-sensitivel
7、inewerehigherthanthatinheat-tolerantline,whiletheincreasedrangeofSODactivity,Procontentinheat-sensitivelinewaslessthanthatinheat-tolerantline.Thepresentstudysuggestedthatdecreasingthephotosyntheticefficiencyofflagleaves,damagingthestructureandfunctionofcellmembrane,a
8、ndresultintheintracellularenvironmentalteringwerethephysiologicalcausesofhightemperatureatearlymilkystagelimitingthegrainplumpnesso
