不同材料生物炭和施用量对小麦和黄瓜种子萌发和根茎生长的影响

为明确不同生物炭材料和添加量对小麦和黄瓜种子萌发和根茎生长的影响,通过分析4种不同材料制备生物炭花生壳生物炭(PBC)、玉米秸秆生物炭(MBC)、杨木屑生物炭(ABC)和竹屑生物炭(BBC)]组分特征,及设计发芽培养试验,测定4种生物炭的不同添加量(0、20.0、40.0、80.0、160.0 g·kg~(-1))对小麦种子(须根系)和黄瓜种子(直根系)发芽率和根、茎生长的影响。结果表明:4种生物炭均呈碱性,孔隙结构明显,表面有-O-、-OH、-C=O等含氧官能团。各生物炭除含有对植物生长有利的营养元素外,其浸提液和施用土壤也测出多种PAHs有机化合物,且不同材料生物炭PAHs含量存在显著差异。与CK相比,生物炭对小麦和黄瓜种子的发芽率无显著影响,但对其根、茎生长影响显著。随着生物炭添加量的增加,两种作物根长和茎长均表现出低添加量促进、高添加量抑制的趋势,达到160.0 g·kg~(-1)生物炭对两种作物的根长和茎长均表现出明显抑制作用。PBC添加量在80.0 g·kg~(-1)时,小麦根长、茎长提高101.67%和173.82%,对黄瓜根长、茎长分别提高了31.58%和85.14%,效果最优;而MBC、ABC和BBC则在添加量为40.0 g·kg~(-1)时达到最优效果,小麦根长、茎长生长率提高了45.26%～83.49%和79.30%～133.17%,对黄瓜根长、茎长生长率提高了18.55%～39.77%和63.14%～84.00%。总体上,各生物炭处理对须根系小麦种子根长和茎长的促进效果优于直根系黄瓜种子。研究表明,不同原料生物炭组分和性质差异显著,其材料种类和投入量均极显著影响小麦和黄瓜根、茎早期生长,且交互作用显著,因此,根据生物炭制备材料,探讨其理化特性,并筛选其最适用量,对生物炭的安全应用具有重要意义。

Effect of different biochar types and applications on germination and rhizome growth of wheat and cucumber seeds

In order to clarify the effects of different biochar types and applications on the germination and rhizome growth of wheat and cucumber seeds, we evaluated four different biocharspeanut shell biochar (PBC), corn stalks biochar (MBC), aspen chips biochar (ABC)and bamboo chips biochar (BBC)] that differed in feedstock type. We also conducted an indoor incubation experiment to evaluate the response of germination percentage and the responses of the root and shoot lengths of wheat seeds (fibrous root syshoot)and cucumber seed (taproot syshoot)to different biochar inputs (0, 20.0, 40.0, 80.0, and 160.0 g·kg^-1)at the end of the germination period. The results showed that the four types of biochars were alkaline in nature and had an obvious pore structure. These biochars also contained functional groups, including -O-, -OH and -C=O. Furthermore, in addition to nutrient elements that can benefit crop growth, several polycyclic aromatic hydrocarbons (PAH) compounds of biochar and soil were also identified and quantified, which differed among the four biochars. Compared with the control, the input of biochar had no effect on the percentage of germination of either wheat or cucumber seeds. Nevertheless, at a low input rate, these biochars effectively promoted the growth of the wheat and cucumber seedlings, whereas a high input of biochar significantly inhibited their root and shoot growth. The application of PBC at 80.0 g·kg^-1 had the best effect with respect to stimulating the root and shoot growth of wheat and cucumber, with increases of 31.58% and 85.14%, respectively. However, MBC, ABC and BBC were most effectives when applied at 40.0 g·kg^-1, promoting increases in the root and shoot lengths of wheat by 45.26%~83.49% and 79.30%~133.17%, and of cucumber by 18.55%~39.77% and 63.14%~84.00%, respectively. Consequently, the different biochars had a considerably greater influence on wheat seedlings than that on cucumber seedlings. In conclusion, differences in both the feedstock type and chemical composition of biochars and their application amounts significantly affected the early growth of wheat and cucumber seedlings, and the interaction of type and application was also significant. Therefore, on the basis of different feedstock types, an examination of the physical and chemical properties of biochars in conjunction with a determination of optimal dosage might be important for reliable field application.