氮同化與合理施肥

1、 植物的礦質(zhì)與氮素營養(yǎng) (Mineral Nutrition and Nitrogen Nutrition in Plant)1第四節(jié) 氮的同化一、植物的氮源空氣 N2土壤無機氮化物有機氮化物 （氨基酸、尿素等）氨態(tài)氮硝態(tài)氮2The nitrogen cycle3生物固氮Substrates and products of nitrogenase(固氮酶)Substrate ProductN2 NH3H+ H2N2O N2, H2OCN- NH3, CH4C2H2 C2H4, C2H64Symbiotic nitrogen fixation5Legumes create root nodule

2、s to house their rhizobial symbionts.6Overview of events leading to formation of legume-rhizobium symbiosis.7Overview of N uptake by a nonnodulated plant (left), and by a nodulated plant with N-fixing symbionts (right).8Enzymology of nitrogen fixati9Proposed model for regulation of nitrate reductase

3、 activity by phosphorylation/dephosphorylation and reversible binding of14-3-3 protein.10第四節(jié) 氮的同化二、硝酸鹽的還原硝酸鹽硝酸鹽還原酶亞硝酸鹽氨亞硝酸鹽還原酶11第四節(jié) 氮的同化二、硝酸鹽的還原1213Nitrate is reduced in the cytosol of root and shoot cellsThe first committed step in the nitrate assimilation pathway is the reduction of nitrate nitrit

4、e. The reaction is catalyzed by NR, a complex metalloenzyme that forms homodimers and homotetramers.NO3-+ NAD(P)H +H+NO2- + NAD(P)+H2O14硝酸還原酶(nitrate reductase, NR) 催化硝酸鹽還原為亞硝酸鹽。真核生物的NR由于來源不同,其亞基組成的數(shù)目和大小也不同,小的有兩個亞基,大的可達八個亞基?，F(xiàn)在認為硝酸還原酶是一種可溶性的鉬黃素蛋白(molybdoflavoprotein) 硝酸還原酶是一種誘導(dǎo)酶(induced enzyme)。 15Do

5、main structure of nitrate reductase(硝酸還原酶)1617亞硝酸還原酶(nitrite reductase,NiR) 催化亞硝酸鹽還原為氨。在正常有氧條件下,由NR催化形成的亞硝酸鹽,很少在植物體內(nèi)積累,因為在植物組織中NiR的存在量大。 亞硝酸還原酶由兩個亞基組成,其輔基由西羅血紅素(sirohaem)和一個4Fe4S簇組成。 181920第四節(jié) 氮的同化二、硝酸鹽的還原21第四節(jié) 氮的同化三、氨的同化22第四節(jié) 氮的同化三、氨的同化232425 AQ=CO2消耗/O2釋放assimulatory quitient26 AQ=CO2消耗/O2釋放assimulatory quitient27282930第五節(jié) 合理施肥的生理基礎(chǔ)一、作物的需肥特點1.不同作物或同一作物的不同品種需肥情況不同2.作物不同需肥形態(tài)不同3.同一作物在不同生育期需肥不同3132第五節(jié) 合理施肥的生理基礎(chǔ)二、施肥的指標 1. 土壤營養(yǎng)豐缺指標 2.作物營養(yǎng)豐缺指標形態(tài)指標生理指標長相葉色體內(nèi)養(yǎng)分狀況葉綠素含量