Timely and accurate estimation of grain yield is valuable for crop monitoring and breeding, and plays an important role in precision agriculture. In this study, we developed a method to predict grain yield based entirely on unmanned aerial vehicle (UAV) data in different rice cultivars under two contrasting climatic regions. Vegetation indices (VIs), which were derived from canopy reflectance collected by UAV, were used to correlate with rice phenotyping and estimate grain yield. It is found that the two-band enhanced vegetation index (EVI2) closely related to leaf area index (LAI) as well as canopy chlorophyll content (CCC), and the red edge chlorophyll index (CI_rededge) related to above ground biomass (AGB). Thus, the phenotyping-related VIs – EVI2 and CI_rededge were exploited to develop yield estimation model. Results showed that the single stage VIs weakly correlated with grain yield of different rice cultivars and was not able to estimate grain yield. By contrast, the multi-temporal VIs can be used to estimate grain yield in different rice cultivars with the estimation error below 7.1 %. In addition, the rice growth duration differed in different climatic zones, which may decrease the estimation accuracy of grain yield by using multi-temporal VIs. After adjusting the phenological stage of multi-temporal VIs used in estimation model, the estimation accuracy of grain yield in different climatic zones increased. In conclusion, this study demonstrated that the UAV-based multi-temporal VIs were reliable for grain yield estimation in different rice cultivars under contrasting climatic zones.

及时准确地估算出谷物的产量，对作物的监测和育种具有重要意义，在精准农业中起着重要的作用。在这项研究中，我们开发了一种完全基于两个不同气候区域下不同水稻品种的无人机数据来预测谷物产量的方法。从无人机收集的冠层反射率中得出的植被指数（VIs）与水稻表型相关并估计谷物产量。研究发现，两波段增强植被指数（EVI2）与叶面积指数（LAI）和冠层叶绿素含量（CCC）密切相关，而红缘叶绿素指数（CI _rededge）与地上生物量（AGB）相关）。因此，与表型相关的VI – EVI2和CI_还原开发了产量估算模型。结果表明，单阶段VI与不同水稻品种的籽粒产量弱相关，无法估算籽粒产量。相比之下，多时相VI可以用于估计不同水稻品种的籽粒产量，其估计误差低于7.1％。此外，水稻在不同气候区的生长期不同，这可能会导致使用多时相VI降低谷物产量的估计准确性。调整估算模型中使用的多时相VI的物候阶段后，提高了不同气候区粮食产量的估算精度。总之，这项研究表明基于UAV的多时相VI在气候条件不同的情况下，对于不同水稻品种的籽粒产量估算是可靠的。