Olk D C, Dinnes D L, Hatfield R D, Scoresby J R, Darlington J W
U.S. Department of Agriculture - Agricultural Research Service, National Laboratory for Agriculture and the Environment, Ames, IA, United States.
U.S. Department of Agriculture - Agricultural Research Service, U.S. Dairy Forage Research Center, Madison, WI, United States.
Front Plant Sci. 2023 Jan 12;13:1058141. doi: 10.3389/fpls.2022.1058141. eCollection 2022.
Agronomic benefits of humic product application to crops are receiving increasing attention, though underlying biochemical changes remain unexplored, especially in field settings. In this study, maize (Zea mays L.) concentrations of 11 phenol and five carbohydrate monomers were determined in whole plant stover (four growing seasons) and roots (two growing seasons) at physiological maturity for two rainfed fields in Iowa (USA) having humic product applications. Stover and root tissues tended toward greater phenol concentrations in a drier upland transect but greater carbohydrate concentrations in a wetter lowland transect. Two humic treatments further accentuated these trends in upland roots. Their phenol content increased significantly with humic application in the droughtier season of root sampling (2013). Phenol increases above the unamended control averaged 20% for each monomer. Total phenols increased above the control by 12% and 19% for the two humic treatments. Five carbohydrate monomers in the upland roots did not respond to humic application. In the second year of root sampling (2014), which had abundant rainfall, upland root phenols did not respond substantively to humic application, but root carbohydrates increased on average by 11 or 20% for the two humic treatments compared to the control, reaching significance (P< 0.10) in 7 of 10 cases. Upland stover phenol concentrations responded differently to humic product application in each of four years, ranging from numeric increases in the droughtiest year (2012) to significant decreases with abundant rainfall (2014). In the lowland transect, root phenols and carbohydrates and stover phenols responded inconsistently to humic application in four years. Stover carbohydrates did not respond consistently to humic application in either transect. The phenols that were more responsive to humic application or to droughtier conditions included p-coumaric acid and syringaldehyde, which are heavily involved in late-season maize lignification. In summary, humic product application further promoted root lignification, a natural response to drought. Yet under non-drought conditions it promoted root carbohydrate production. Carbohydrate production might be the intrinsic plant response to humic product application in stress-free conditions. These results indicate complex interactions in field conditions between plant biochemistry, environmental signals, and the humic product.
腐殖质产品应用于作物的农艺效益正受到越来越多的关注，不过其潜在的生化变化仍未得到探索，尤其是在田间环境中。在本研究中，测定了美国爱荷华州两块施用腐殖质产品的雨养田在生理成熟时全株秸秆（四个生长季）和根系（两个生长季）中11种酚类和5种碳水化合物单体的含量。在较干燥的高地样带中，秸秆和根系组织中的酚类浓度往往较高，而在较湿润的低地样带中，碳水化合物浓度较高。两种腐殖质处理进一步加剧了高地根系中的这些趋势。在根系采样的较干旱季节（2013年），随着腐殖质的施用，其酚类含量显著增加。每种单体的酚类增加量比未改良对照平均高出20%。两种腐殖质处理的总酚含量比对照分别高出12%和19%。高地根系中的5种碳水化合物单体对腐殖质施用没有反应。在根系采样的第二年（2014年），降雨充沛，高地根系中的酚类对腐殖质施用没有实质性反应，但两种腐殖质处理的根系碳水化合物含量相比对照平均增加了11%或20%，在10个案例中有7个达到显著水平（P<0.10）。高地秸秆中的酚类浓度在四年中的每一年对腐殖质产品施用的反应都不同，从最干旱年份（2012年）的数值增加到降雨充沛时（2014年）的显著下降。在低地样带中，根系酚类和碳水化合物以及秸秆酚类在四年中对腐殖质施用的反应不一致。在两个样带中，秸秆碳水化合物对腐殖质施用的反应都不始终如一。对腐殖质施用或较干旱条件反应更敏感的酚类包括对香豆酸和丁香醛，它们在玉米后期木质化过程中起重要作用。总之，腐殖质产品的施用进一步促进了根系木质化，这是对干旱的一种自然反应。然而在非干旱条件下，它促进了根系碳水化合物的产生。碳水化合物的产生可能是植物在无胁迫条件下对腐殖质产品施用的内在反应。这些结果表明在田间条件下，植物生物化学、环境信号和腐殖质产品之间存在复杂的相互作用。
