生物炭对R2期大豆根系生长和氮磷吸收利用的影响

为了探讨生物炭对大豆植株及籽粒养分吸收利用的影响,采用盆栽试验,设置4个生物炭用量处理(0%、1%、5%、10%,生物炭/干土重),分析了不同处理下R2期大豆根系和植株形态特性以及植株体内氮和磷的转移情况。结果表明,施用生物炭会增加土壤中有机碳、全氮和速效磷含量,并对大豆根系发育和植株生长产生积极影响。5%和10%生物炭处理会显著增加大豆叶面积(分别较对照高62.0%和74.5%)和植株鲜重(分别较对照高57.1%和72.6%),提高茎叶的氮磷转移量,显著提高籽粒产量(平均比对照高51%)。10%生物炭处理会显著增加大豆总根长、根表面积、根体积和比根长以及氮、磷收获指数,分别较对照高19.4%、25.1%、27.4%、28.7%、10.7%和8.9%。生物炭对大豆根系发育的影响主要是促进了细根(<0.5mm)的伸长和增长,在1%、5%和10%生物炭处理下,细根长度占植株根系总长度的比例从无生物炭处理的71.4%分别增加到76.4%、82.7%和84.6%。相关分析结果表明,大豆籽粒产量与土壤全氮和速效磷含量以及氮磷收获指数均呈现显著的正相关关系,根长与土壤养分含量、氮磷收获指数以及氮、磷转移量也均呈现显著的正相关关系。总之,施用一定量的生物炭能够对土壤养分含量产生积极影响,并促进大豆根系生长,影响大豆植株体内养分吸收和利用,提高籽粒产量。

Effect of biochar on grain yield and leaf photosynthetic physiology of soybean cultivars with different phosphorus efficiencies

This study was conducted with two soybean cultivars, Liaodou 13 (L13, phosphorus (P)-efficient) and Tiefeng 3 (T3, P-inefficient), to investigate the effects of biochar on soybean yield and photosynthetic physiological parameters, at four biochar application rates (0, 1, 5, and 10%, w/w), and two fertilization treatments (0 and 150 kg ha–1). Grain yield, plant biomass, P accumulation, leaf net photosynthetic rate (Pn), chlorophyll index (Chl), nitrogen balance index (NBI), sucrose phosphate synthase (SPS), and sucrose synthase (SS) activities, soluble sugar, sucrose and starch contents, and leaf area duration (LAD) were measured. Biochar had positive effects on Pn, Chl, NBI, SPS, and SS activities, and leaf soluble sugar, sucrose, and starch contents of both genotypes, these effects increased with biochar application rate. L13 benefited more efficiently from biochar than T3 did, as the grain yield of L13 significantly increased by 31.0 and 51.0%, at 5 and 10% biochar, respectively, while that of T3 increased by 40.4 at 10% biochar application rate, as compared with controls. The combined application of biochar and fertilizer boosted the positive effects described, but no difference was found for grain yield in L13 among biochar application rates, while grain yield of T3 continually increased with biochar rate, among which, 1% biochar combined with 150 kg ha–1 fertilizer resulted in T3 yield increment of more than 23%, compared with the application of 150 kg ha–1 fertilizer alone. Altogether, our results indicated that the application of biochar enhanced carbon assimilation in soybean, resulting in increased biomass accumulation and yield. Differences in genotypic responses to biochar highlight the need to consider specific cultivars and biochar rate, when evaluating the potential responses of crops to biochar.