College of Agricultural Science and Engineering, Hohai University, Nanjing 210098, China.
College of Agricultural Science and Engineering, Hohai University, Nanjing 210098, China.
Sci Total Environ. 2022 Sep 10;838(Pt 4):156528. doi: 10.1016/j.scitotenv.2022.156528. Epub 2022 Jun 7.
The N natural abundance is an effective indicator of nitrogen dynamics in plants. The impact of different irrigation regimes as a function of varied soil clay contents on stable nitrogen isotope abundance (δN) in rice remains unknown. Therefore, the response of δN and nitrogen utilization efficiency (NUE) of rice to different combinations of alternate wetting and drying irrigation (AWD) and clay contents were investigated. The study included three AWD regimes, viz. I100, (100 % saturation, 30 mm flooded), I90 (90 % saturation, 30 mm flooded) and I70 (70 % saturation, 30 mm flooded), and three soil clay content treatments, viz. 40 % (S40), 50 % (S50), and 60 % (S60) clay content. Compared with I100, I90 and I70 with high clay content (S60) significantly increased the crack volumes and N leaching losses and reduced the total N accumulation and different forms of NUE of rice plants. The values of δN in above-ground organs and soil were greatly increased by I90 and I70 irrigation regimes compared to I100. An increasing trend of organs δN from root to shoot was found for all three irrigation regimes. Significant negative relationships were found between (i) N partial factor productivity (PFP) and grain N, (ii) PFP and leaf N, and (iii) N harvest index (NHI) and leaf N. These significant negative relationships might contribute to the increased N losses and changed N allocation under AWD with high clay contents. Hence, it is suggested that cracks should be taken into consideration in rice cultivation. Moreover, δN may serve as an effective indicator of NUE in rice grown under AWD irrigation with high clay contents as well as an indirect indicator for assessing the N loss in agro-ecosystems.
氮自然丰度是植物氮动态的有效指标。不同灌溉制度（不同土壤粘粒含量）对水稻稳定氮同位素丰度（δN）的影响尚不清楚。因此，研究了不同交替湿润和干燥灌溉（AWD）和粘粒含量组合对水稻δN和氮利用效率（NUE）的响应。该研究包括三种 AWD 制度，即 I100（100%饱和，30mm 淹没）、I90（90%饱和，30mm 淹没）和 I70（70%饱和，30mm 淹没），以及三种土壤粘粒含量处理，即 40%（S40）、50%（S50）和 60%（S60）粘土含量。与 I100 相比，高粘土含量（S60）下的 I90 和 I70 显著增加了裂缝体积和氮淋失损失，降低了水稻植株的总氮积累和不同形式的 NUE。与 I100 相比，I90 和 I70 灌溉制度显著增加了地上器官和土壤的δN 值。在所有三种灌溉制度下，从根到茎的器官δN 呈增加趋势。发现三个灌溉制度之间存在以下显著负相关关系：（i）氮部分生产力（PFP）与籽粒氮，（ii）PFP 与叶片氮，和（iii）氮收获指数（NHI）与叶片氮。这些显著的负相关关系可能导致 AWD 下氮损失增加和氮分配改变。因此，建议在水稻种植中考虑裂缝。此外，δN 可作为 AWD 灌溉下高粘土含量水稻 NUE 的有效指标，以及评估农业生态系统氮损失的间接指标。
