密度和修剪对冬小麦根系时空分布和产量的影响

Effects of seeding rate and root pruning at different growth stages on spatiotemporal root distribution,soil water use and grain yield of winter wheat in Loess Plateau

田间试验研究了种植密度和不同时期根修剪对黄土旱塬冬小麦(Triticum aestivum L.)根系时空分布、土壤水分利用以及产量的影响。供试材料为该地区广泛种植的冬小麦品种长武135。试验设定4个密度处理:SR1、SR2、SR3和SR4,分别为180、225、280和340株/m2,其中SR2为常规密度;以及4个根修剪处理:CK(不剪根处理)、W(越冬期根修剪)、S(返青期根修剪)和B(越冬期根修剪+返青期根修剪)。研究结果表明,冬小麦返青期、孕穗期和花期根系总干重随种植密度的增加而增加。根修剪处理显著降低了各生育期冬小麦根系总干重,不同处理间排序为CK>W>S>B。种植密度和根修剪对冬小麦根系总长度的影响与根系总干重类似,各处理间根系总干重和根系总长度的差异主要来自于0—20 cm表土层。冬小麦表土层(0—20 cm)中的根干重密度(DRWD)和根长密度(RLD)都随种植密度的提高而增加。根修剪降低了返青期、孕穗期和花期冬小麦DRWD和RLD在0—20 cm表土层中的分布,但增加了花期60—100 cm深土层中的DRWD和RLD。整个生育期土壤水分消耗随种植密度增加而增加,而根修剪显著减少土壤水分的消耗。冬小麦的产量和水分利用效率随着种植密度增加而显著提高。根修剪处理显著增加了冬小麦的产量,且W处理的产量最高,同时根修剪也显著提高了冬小麦的水分利用效率。由此可见,越冬期根修剪(W)可以最大程度提高冬小麦产量。考虑到经济效益,建议旱地雨养农业区在较高的密度下进行越冬期根修剪处理,从而达到生产上高产高效的目的。

This study was to investigate the effects of combined application of actinomycetes Act12 bio-control agents and potassium humate on growth and microbial flora in rooting zone of Salvia miltiorrhiza Bge. Taking conventional transplantation treatment as control,we used root dipping with actinomycetes Act12 bio-control agents and potassium humateto evaluate survival rate,biomass and resistance to root-knot nematode of S. miltiorrhiza; The abundances of soil bacteria（B）,fungi（F） and actionmycetes（A） were determined using the dilution plating technique. Predominant microorganisms were identified using 16 S rRNA and ITS sequence analysis. Results were used to evaluate the microecological changes in soil microflora of S. miltiorrhiza root zones with combined application of actinomycetes Act12 bio-control agents and potassium humate. The results showed that： 1） Under Act12 combined with potassium humate treatment（ T20）,emergence rate increased by 8. 7% compared with the control treatment,and mortality rate decreased by 39. 0%; Stem-leaf natural weight,root natural weight,root natural weight per plant,root dry weight and root dry weight per plant were 6. 1% 、28.6% 、11. 1% 、36. 3% and 9. 0% higher than the control,respectively. 2） Combined application of Act12 agents and potassium humate can adjust soil microecological balance,modify microflora and microbial community composition. In rhizoplane soil,compared with the control treatment,A / F increased by 95. 0% under Act12 combined with potassium humate treatment. In S. miltiorrhiza roots,under Act12 combined with potassium humate treatment,the number of bacteria was 195. 0% higher than the control. While fungi and actinomyctes were not detected. 3） In rhizosphere and rhizoplane soil with Act12 and potassium humate,6 predominant microorganisms might be beneficial,which included 3 bacteria isolates namely A. nitroguajacolicus, R. radiobacter and P. frederiksbergensis, 3 actinomycetes isolates namely S.diastatochromogenes,S. lateritius and S. cavourensis; 2 predominant microorganisms were suspected harmful isolates,included 1 bacteria isolate B. frigoritolerans and 1 actinomycetes isolate S. turgidiscabies. 4） Combined application of Act12 agents and potassium humate may control the disease of root-knot nematode. The disease incidence of root-knot nematode in S. miltiorrhiza decreased by 49. 3% under using Act12 agents combined with potassium humate. These results suggested that the combined application of Act12 bio-control agents and potassium humate not only promoted S. miltiorrhiza growth and yield,but also enhanced plant disease resistance and adjusted soil microecological balance in rooting zone.