Water regulation characteristics of winter wheat root at jointing stage in different nitrogen, phosphorus and water couplings | 水氮磷耦合对拔节期冬小麦根系水分调节特性的影响

Chinese. 研究不同水氮磷耦合条件下，冬小麦根系形态、生理和细胞结构变化与功能的关系。采用盆栽调亏灌溉的方法，以“小偃22”为试材，采用拌肥方式于播种时设低肥N1P1(纯氮 0.1 g/kg、P2O5 0.05 g/kg)和高肥N2P2(纯氮0.3 g/kg、P2O5 0.15 g/kg)2个氮磷肥处理；在拔节期设土壤含水量分别为田间持水量的70%～85%（正常供水,CK）、55%～70%（轻度亏缺,LS）和40%～55%（重度亏缺,SS）3个水分处理。于水分亏缺处理20 d后取样，从形态学、生理代谢和解剖学层面研究拔节期不同水氮磷耦合对冬小麦根系水分调节特性的影响。在相同营养条件下，拔节期水分亏缺会导致冬小麦地下部干物质量、地上部干物质量和总生物量减小；但根冠比增加，与CK相比，LS、SS在N1P1和N2P2 2种氮磷肥处理条件下，根冠比分别升高了32.3%，14.3%和11.5%，4.7%；根毛密度也明显增加。水分亏缺造成冬小麦根系皮层薄壁细胞体积变大，皮层占根系直径的比例增加；木质部导管横截面积显著减小，低肥条件下LS、SS分别较CK减小17.11%，43.32%，高肥条件下分别较CK减小11.10%，46.70%，并伴随有导管变形。同时，水分亏缺可以使冬小麦根系活力提高，游离脯氨酸、可溶性糖的合成和积累增加，从而提高其水分调节特性。同一水分状况下，与低肥条件相比，高肥条件能明显提高拔节期冬小麦的抗旱性。拔节期冬小麦在高肥轻度水分亏缺条件下，能够从代谢和结构2个层面作出更为合理、协调的综合性响应来维持植物体内的水分平衡，提高其水分利用效率和抵抗干旱的能力。

English. The research was to study the relationships between the change of morphology, physiology and cell structure of winter wheat root in different nitrogen, phosphorus and water couplings and function. Taking Xiaoyan 22 as test materials in pot experiments, mixed fertilizer at seeding time set two nitrogen phosphorus fertilizer processing: low fertilizer N1P1 (pure nitrogen 0.1 g/kg, P2O5 0.05 g/kg) and high fertilizer N2P2 (pure nitrogen 0.3 g/kg, P2O5 0.15 g/kg); Setting three water treatments at jointing stage: soil moisture content in proportion to field moisture as 70%-85% (CK), 55%-70%(LS), 40%-55%(SS). After water deficit treatment for 20 days, the morphological, physiological and anatomical comparative studies on the effect of moisture adjustment characteristic on root of winter wheat in different nitrogen, phosphorus and water couplings were carried out. Under the same nutritional conditions, dry weights of both the underground and ground parts of winter wheat were reduced at the jointing stage in water deficit. And the total biomass was declined. In contrast, the root-top ratio was increased. When dealing with N1P1 and N2P2, the data of LS and SS were 32.3%, 14.3% and 11.5%, 4.7% higher than CK, respectively. And the density of root hairs was apparently increased as well. Due to water deficit, the volumes of root cortex parenchyma cells and cortex accounted for the root diameter were increased, too. While the cross-sectional area of xylem conduit was significantly reduced, LS and SS under low-fat conditions and high-fat conditions were reduced by 17.11%, 43.32% and 11.10%, 46.70% respectively when compared with CK and accompanied by catheter deformation. At the same time, water deficit can improve the root activity and its water regulation functions, and promote the synthesis and accumulation of free proline and soluble sugar. Under the same moisture conditions, compared with low-nutrient conditions, high nutrient conditions will significantly improve winter wheat drought resistance at the jointing stage. Under the high-fertilizer and lighter water deficit conditions, winter wheat at jointing stage can maintain water balance of inside plants, rely on comprehensive response from reasonable coordinated metabolism and structure, and improve their ability to resist drought and increase efficiency of water usage.