Abstract
Paddy rice is one of the most widely planted crops in Asia. Yield estimation of paddy rice is crucial to food security. Gross primary productivity or net primary productivity (NPP) models are some of the most commonly used methods for crop yield estimation as they have a theoretical basis and are simple to use. The harvest index (HI) of paddy rice, one of the input parameters in yield estimation models, has been increasingly used with the improvement of paddy rice cultivars over the past four decades. However, in many previous researches, this parameter was arbitrarily determined to fit the observed yield data values, without considering its changing trend. In the present study, we developed an NPP-based rice yield estimation model with HI being a changing parameter. The accuracy of the proposed method is tested over the Jiangsu Province, Southeast China. The results showed that the rice HI increases linearly in study area. Compared with yield estimation with a fixed HI, yield estimations using a changing HI are greatly improved, with the average estimation accuracy greater than 96%, and the relative errors within ±5%. The results proved that the NPP-based yield estimation model with a changing HI can be a promising alternative for rice yield estimation.
Highlights
T HE global human population is estimated to reach 9.7 billion by the year 2050 [1] and this makes the availability of the rice grain extremely important for food security
Comparing estimated rice yields with statistical rice yields (Fig. 7), it is observed that data points are near to 1:1 line, and estimated yields calculated by the proposed estimation model are close to the statistical yield
The test results shown that 76.92% of the relative errors of estimated yields are within ±5%, occupation increased by 45.45% compared with those that obtained by the model with a fixed harvest index (HI)
Summary
T HE global human population is estimated to reach 9.7 billion by the year 2050 [1] and this makes the availability of the rice grain extremely important for food security. A range of factors, including sharp increase of population, decline in arable area, water pollution and water resource shortage, environmental pollution and global climate change, significantly affects agricultural production and threatens grain security [2]. Grain security has become a tremendous challenge in many countries and regions. Paddy rice is one of the most important and widely planted crops in the world, especially in Asia [3], providing an half of mankind’s calories. Manuscript received January 19, 2020; revised April 3, 2020 and May 3, 2020; accepted May 6, 2020.
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