硼对平邑甜茶幼苗硝态氮吸收、利用及分配特性的影响

Effects of Boron on Absorption,Utilization and Distribution of Nitratenitrogen of Malus hupehensis Seedlings

以平邑甜茶幼苗为试材,运用^(15)N同位素示踪和非损伤微测技术,研究了不同供硼(硼酸0、1.0、2.0、3.0、4.0、5.0和6.0 mg·L^(-1))水平对平邑甜茶根系生长及氮素吸收、利用和分配特性的影响。结果表明,3.0 mg·L^(-1)硼酸处理的幼苗根系活力及根系形态指标显著高于其他处理,幼苗的全氮量及^(15)N吸收量增幅最大,分别比对照提高了19.4%和75.0%。随供硼水平的增加,植株氮素利用率呈现先增高后降低的趋势,在3.0 mg·L^(-1)硼酸处理时最大,为14.8%,是对照的1.8倍。施硼处理对幼苗的^(15)N分配率有一定的影响,3.0 mg·L^(-1)硼酸处理的根系^(15)N分配率达到最大,且显著高于对照。非损伤微测结果显示,3.0 mg·L^(-1)硼酸处理时,平邑甜茶根系对NO_3^-有强烈吸收且内流速度达到最大,在缺硼和高硼(硼酸0和6.0 mg·L^(-1))处理时有明显外排趋势。因此,3.0 mg·L^(-1)硼酸处理最有利于平邑甜茶根系的生长、根系活力的提高和氮素的吸收利用,而低硼和过量供硼均会抑制根系生长及氮素的吸收利用。

Malus hupehensis Rehd. seedlings were used as test materials, study the effect of different boron concentrations （0, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 mg·L^-1 boric acid） to Malus hupehensis Rehd. seedlings root growth, nitrogen uptake, utilization and distribution using 15N isotope tracer and non-damage microtest techniques. The results showed that root vigor and root morphological index of seedlings treated with 3.0 mg ·L^-1boric acid treatment were significantly higher than those of other treatments. Compared with the control, the total N and 15N uptake of 3.0 mg ·L^-1 boric acid treatment increased by 19.4% and 75.0%, respectively. With the increase of boron supply, the nitrogen use efficiency of plants increased first and then decreased, and it was 14.8% at 3.0 mg ·L^-1 boric acid treatment, which was 1.8 times of the control. The effect of boron treatment on the 15N partitioning rate of seedlings was significant, and the root partition rate of 3.0 mg ·L^-1 boric acid treatment was the highest and significantly higher than that of the control. The results of non-damage microtest showed that the root absorption of NO3- was strong and the influx velocity was the highest in 3.0 mg ·L^-1 boric acid treatment, and obvious efflux in the treatments of boron deficiency （0 mg ·L^-1 boric acid） and high boron （6.0 mg ·L^-1 boric acid）. Therefore, 3.0 mg ·L^-1 boric acid treatment was most beneficial to the root growth, root activity and nitrogen absorption and utilization of Malus hupehensis, while low boron and excess boron could inhibit roots growth and nitrogen uptake and utilization.