基因型影响磷镁互作下大豆生长及根瘤和菌根性状

【目的】明确施加镁肥在不同磷处理的土壤上对不同基因型大豆生长及根瘤和菌根性状的影响。【方法】田间试验采用三因素试验设计，设置施P₂O₅ 40 kg/hm² (P40)和100 kg/hm² (P100)两个水平，施MgO 0kg/hm² (Mg0)和75 kg/hm² (Mg75)两个水平，磷高效基因型粤春03-3 (YC03-3)和磷低效基因型本地2号(BD2)两个大豆基因型。测定了大豆植株干重、单株结荚数、根系性状、根瘤性状、菌根侵染率以及植株氮、磷、镁含量。【结果】P100处理显著增加了两个大豆基因型的植株干重、单株结荚数、总根长、根表面积和体积以及植株氮、磷、镁积累量。施用镁肥，YC03-3在P40和P100处理下植株干重、单株结荚数、植株氮和镁积累量均显著增加，在P100条件下植株磷积累量以及根表面积、根体积、根平均直径显著增加；BD2在P40和P100处理下植株镁积累量显著增加，P40条件下植株氮积累量显著增加。磷和镁处理显著影响大豆与有益微生...

Genotype affects the interaction of phosphorus and magnesium on soybean growth,nodule and mycorrhizal traits

  【Objectives】  The effects of magnesium (Mg) fertilizer on plant growth, nodule and mycorrhizal traits of different soybean genotypes were studied with different phosphorous (P) treatments.  【Methods】  A three-factor-two-level field experiment was conducted in Ningxi farm, South China Agricultural University. The three factors were P₂O₅ level in 40 kg/hm2 (P40) and 100 kg/hm2 (P100), MgO level in 0 (Mg0) and 75 kg/hm2 (Mg75), and soybean genotypes of P-efficient Yuechun 03-3 (YC03-3) and P-inefficient Bendi No.2 (BD2). Plant dry weight, pod number, root and nodule traits, mycorrhizal colonization rate, and plant N, P, and Mg contents were measured.   【Results】  Compared with P40, P100 significantly increased plant dry weight, pod number, total root length, root surface area and volume, and the uptake of N, P, and Mg in the two soybean genotypes. For P-efficient genotype YC03-3, Mg75 treatment significantly increased the plant dry weight, pod number, plant N and Mg uptake under both P40 and P100 levels, and increased plant P uptake, root surface area, root volume, and average root diameter under P100 condition. For P-inefficient genotype BD2, Mg75 significantly increased plant Mg uptake under P40 and P100, and increased plant N uptake under P40. P and Mg treatments markedly affected the symbiosis between soybean and beneficial microorganisms. Mg75 did not affect the nodule number and dry weight of the two soybean genotypes under P40 condition, but increased the nodule number of BD2 and YC03-3 by 135% and 178%, and the nodule dry weight by 308% and 197% under P100 condition, respectively. P40 increased the mycorrhizal infection rate of YC03-3 by 31.6% under Mg0 and increased that of BD2 by 15% under Mg75, compared to the corresponding P100 treatment. Mg75 increased the mycorrhizal colonization rate of BD2 by 16.3 % under P40 condition, and increased that of YC03-3 by 32.1% under P100 condition. Principal component analysis showed that a significant difference existed between Mg0 and Mg75 treatments under P100 condition, but no significant difference under P40.  【Conclusion】  The higher P fertilizer (P100) substantially boosts the growth of the two soybean genotypes, and improves the nutrient status of N, P, and Mg. The Mg fertilizer increases the shoot and root dry weight, pod number, and plant N uptake of P-efficient genotype YC03-3. P and Mg exhibits significant interaction on the nodulation and mycorrhizal traits of two soybean genotypes, the nodule density of YC03-3 is more sensitive than BD2 to P and Mg application. The mycorrhizal colonization rate of BD2 is more sensitive to Mg supply under low P supply (P40), while that of the YC03-3 is more sensitive to Mg application under high P supply (P100). Therefore, soybean genotypes influence the interaction of P and Mg nutrients.