干湿交替灌溉耦合施氮对水稻根系性状及籽粒库活性的影响

以新稻20为材料进行土培试验，设置浅水层灌溉(0 kPa)、轻度水分胁迫(–20 kPa)和重度水分胁迫(–40 kPa) 3种灌溉方式及0氮(0N, 0 kg hm-2)、中氮(MN, 240 kg hm-2)和高氮(HN, 360 kg hm-2) 3种氮水平，研究不同水氮耦合处理对水稻根长、根冠比、根系伤流、根系有机酸含量、根系玉米素及玉米素核苷与籽粒酶活性的影响。结果表明，灌溉方式与施氮量存在显著的互作效应，轻度水分胁迫增加了主要生育期根长、根系伤流量、根系分泌物中有机酸总量、根系玉米素及玉米素核苷含量，提高籽粒ATP酶、蔗糖合酶及腺苷二磷酸葡萄糖焦磷酸化酶活性，降低穗分化后水稻根冠比，且与MN耦合后产量最高，为本试验最佳的水氮耦合运筹模式；重度水分胁迫则显著降低主要生育期根长、根系伤流量、根系分泌物中有机酸总量、根系玉米素及玉米素核苷含量，降低籽粒ATP酶、蔗糖合酶及腺苷二磷酸葡萄糖焦磷酸化酶活性，增加主要生育期根冠比。水稻籽粒产量与主要生育期水稻根长、根系伤流量、根系分泌物中有机酸总量、根系玉米素及玉米素核苷含量均呈显著或极显著的正相关，而穗分化至成熟期根冠比与水稻产量呈负相关；同时水稻根长、根系伤流量、根系分泌物中有机酸总量、根系玉米素及玉米素核苷含量与籽粒ATP酶、蔗糖合酶及腺苷二磷酸葡萄糖焦磷酸化酶活性呈显著或极显著的正相关。表明通过适宜的肥水调控发挥水氮耦合效应，可以创造良好的根系形态、提高水稻根系代谢能力和籽粒库的生理活性，促进水稻高产。

Effect of Wetting and Drying Alternative Irrigation Coupling with Nitrogen Application on Root Characteristic and Grain-sink Activity

Soil moisture and nitrogen nutrient are the two principal factors affecting rice production. Elucidation of their coupling effects on grain yield of rice (Oryza sativa L.) has great significance for high yielding and high efficiency in production. The purposes of this study were to investigate the coupling effects of water and nitrogen on root traits and grain-sink activity. A field experiment was conducted using a mid-season japonica rice cultivar of Xindao 20 with three treatments of different nitrogen levels, including 0N, MN (240 kg ha-1) and HN (360 kg ha-1), and three irrigation regimes, including submerged irrigation (0 kPa), alternate wetting and moderate drying (–20 kPa) and alternate wetting and severe drying (–40 kPa) in 2013 and 2014. There was a significant interaction between irrigation regimes and nitrogen applications, with a similar result in two years. The grain yield was the highest in the treatment of MN coupling with mild water stress due to improved seed filling rate and grain weight. In the same nitrogen level, root length, root bleeding, organic acid and Z+ZR contents in roots at main growth stages were higher in treatment of alternate wetting and moderate drying than in treatment of submerged irrigation, meanwhile activating of ATPase, sucrose synthase and adenosine phosphate glucose pyrophosphorylase (AGPase) activity in grain were also increased during grain filling period, but root-shoot ratio was lower after panicle initiation stage. The treatment of mild water stress and MN enhanced rice yield and nitrogen use efficiency, being the best water-nitrogen coupling management model in this paper. The opposite result was observed under the condition of alternate wetting and severe drying. Grain yield positively correlated with root length and root metabolism indices at main growth stages and negatively correlated with ratio of root to shoot at the stage of heading. A negative correlation was observed between root-shoot ratio and activating of ATPase, sucrose synthase and AGPase in grain, while a significant or very significant and positive correlation between root length, root metabolism traits and aboveground development. These results suggest that a good root morphology, increasing root metabolism and aboveground development capabilities through the appropriate regulation of water coupling with nitrogen application will be much more beneficial to increasing grain yield in rice.