| Rice is cue of tie most impoitant anps in China It is of great significance to hierease largely erop yield per acie on the present basis aix] discover photosynilic nedianism by ovmg photosyndic efficiency Photosynthetic perarnetas of flag leaves of two s of tice hybrids were systanlilLcally analyzed during leaf photosynthetic fixetion decline. lAPS (Instantaneous aamit photosynthesis rate) displayed APD (Active photosynthetic during) aix] SF1?(Sharp Fall phase) while tie chlorophyll content displayed RSP (Relative Steady Phase) and SF1?during leaf pkK)tosyntletc function decline. The decline of RuBPCase activity was obviously aster than that offrtosyntietic electttm transfer activity. Thfore hiaeasing RuBPCase carboxylase efficiency has become one of keys to imriove photosynthetic efficiency. lie relationship of leaf scxmx capacity (which is tie total amoinit of assimilated CO2 of leaf cluing whole life) in flag leaf to yield traits was studied. lie results showed that tie relationships betwcai leaf source capacity hi flag leaf and yield per plant city weight per panicle, full spikekts per panide were all positive significant at 1% level, confirming its tight conelaficm with yield fruits. Path analysis further showed that APD had the largest direct eflcts on leaf souree capacity, while leaf area tie smallest. Tie results also showed that lie differuice of leaf soiree capacity in flag leaves among rice varieties was significant at 1% level aid accordingly among gax)types ii rice, indicating it is viable for rice varieties with high leaf source capacity to be selected Also, tl was variation of leaf source capacity hi rice, aid its variation coefficient within a rice variety was 6.l9l7.34%, suggesting that leaf source capacity maybe regulated by some planting measures. The nediod of assaying supaxide anion content in plant was improved by adding ice acetic acid hi key regents, which increased sensitivity by 50 % superoxjde anion fivm plant leaves, adding EDTA aid hydmxylarnine could inhii,it SOD activity aid fixing supezo,dde anion in situ. By this wy tie st.oxide anion amitait could reflect the truth M situ. We also found supaoxide anicm was not generated frm stwnatant, which indirectly confirmed that peroxide anion is flomphotosyndiic maub,ure. lie effects of SDS titmdon on the atmcture and inactivation of rice Rubison v.e studied. As a detergent, S1)S, when in low has the similar character wietasyntietic membrane. The study on the effect of SDS on tie stnctize and inactivation of rice Rubisco 1psto tnxieratumi tie hitaaction of Rnbisco with p tosynthetic nnlnie. lie results showecL Rnbisco lost all carboxylase activity in lowof SDS (0.4mM)aid most sulfiiydiyl groq exposed; when SDSined, SSU fii dociHnd from Rubisoo holocnzyme. The tertiary structure of Rubisco was hanged by SDS tzUnmit bit seccmdary structurc little aflbeted. We can find that tie conhruatianakhange of active site of Rubiaco is ster tan that ofholoa]zyme of 11202 on the atnicture aid inactivation of rice Rnbisco vu inve4gated. The tertiary aix] secondary sxs were little inThiezeed by 0-20mM H2 taeat that as thought to be in physiological concu1ia.L While tie hydrophobic sure of Ruihisco increased to lie maximum by 2(knM H202 treaflyrmt lie tertiary aid seccrdary stwcUzrc changed greatly when H202 concermm was ne than 20mM. Tie content of ez4zlix dedlied obviously flom 20% in native form to zero by 60mM 11202 kattnert lie hychuphobic surface content also declined but a...
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