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为明确氮肥施用模式对小麦茎秆木质素合成与积累及抗倒伏能力的影响,2011—2012和2012—2013生长季,选用济麦22(抗倒伏)和山农16(不抗倒伏)品种,分析不同生育期追施氮肥处理的茎秆木质素含量和木质素合成相关酶活性,及其与抗倒伏指数和产量的关系。各处理总施氮量为240 kg hm-2,其中80 kg hm-2播前基施,其余氮肥按4种模式追施,分别是起身期和孕穗期各一半(N1)、拔节期全施(N2)、拔节期和开花期各一半(N3)和孕穗期全施(N4)。与N2和N3处理相比,N1和N4处理的茎秆木质素含量高,茎秆抗折力大,茎秆抗倒能力强。各处理对木质素合成关键酶活性有显著影响,其中N1的苯丙氨酸解氨酶(PAL)、酪氨酸解氨酶(TAL)和过氧化物酶(POD)活性较高;N2处理第2节间形成后0~7 d时PAL、TAL和POD活性显著高于其他处理,但第2节间形成后21 d时迅速下降;N3处理第2节间形成后0~21 d时PAL、TAL和POD活性低,但开花期(21 d)追氮延缓了3种酶活性的降低;N4处理显著提高了第2节间形成14 d后的酶活性。在乳熟期和蜡熟期,两品种的基部茎秆抗折力和抗倒伏指数均以N1和N4处理显著优于其他处理,并且N1和N4处理的籽粒产量也显著高于其他处理。试验结果表明,孕穗期追肥的N1和N4处理有助于提高茎秆中PAL、TAL、POD活性及木质素含量,提高小麦茎秆的机械强度及抗倒伏能力,降低小麦倒伏面积和倒伏程度。
In order to clarify the effects of nitrogen application mode on the lignin synthesis, accumulation and lodging resistance of wheat stalk, during the growing season of 2011-2012 and 2012-2013, the varieties of Jimai 22 (lodging resistance) and Shannon 16 (non-lodging resistance) The lignin content and lignin biosynthesis-related enzyme activities of culm cultivated at different growth stages under topdressing nitrogen application and their relationship with lodging resistance index and yield were analyzed. The total N application rate was 240 kg hm-2. Among them, 80 kg hm-2 was basal application before sowing, and the other nitrogen fertilizers were topdressing in 4 modes, which were respectively half of initiation and booting (N1) (N2), half of the jointing and flowering stages (N3) and full booting stage (N4). Compared with N2 and N3 treatment, the content of lignin in the stems treated with N1 and N4 was high, the stems had high anti-fracture ability and strong stem lodging resistance. Each treatment had a significant effect on the key enzyme activities of lignin synthesis, of which N1, PAL, TAL and POD activities were higher; The activities of PAL, TAL and POD at 0 ~ 7 d after the formation of the second internode were significantly higher than those of other treatments, but decreased rapidly at 21 d after the formation of the second internode. At 0 ~ 21 d after N3 treatment, the PAL , TAL and POD activities were low. However, the dephosphorylation at the flowering stage (21 d) retarded the activity of three enzymes. N4 treatment significantly increased the enzyme activity after 14 days of formation in the second internode. At milky ripening stage and wax ripening stage, the bending strength and lodging resistance index of the base stem of both cultivars were significantly better than those of other treatments in N1 and N4 treatments, and the grain yield of N1 and N4 treatments were also significantly higher than those of other treatments. The results showed that treatment with N1 and N4 at the booting stage could improve PAL, TAL, POD activity and lignin content in the culm, increase the mechanical strength and lodging resistance of wheat stalks and reduce the lodging area and lodging of wheat.