Abstract
Paddy rice is one of the most important cereal crops worldwide, so it is very important to accurately monitor its growth status and photosynthetic efficiency. The nitrogen (N) level is a key factor closely related to crop growth. In this study, laser-induced fluorescence (LIF) technology combined with multi-variate analysis was applied to investigate the effect of paddy rice variety on N fertilizer level monitoring. Principal components analysis was conducted to extract the variables of the main fluorescence characteristics to identify N levels. Experimental results demonstrated that no nitrogen fertilizer can be completely identified for each paddy rice variety. In addition, other N levels can also be well classified based on the fluorescence characteristics. The relationship between the fluorescence ratio (F735/F685 : F735, and F685 denote the fluorescence intensity at 735 nm, and 685 nm, respectively) and leaf N content of different paddy rice varieties is also discussed. Experimental results revealed that LIF technology is an effective method of monitoring the N fertilizer and leaf biochemical components of paddy rice.
Highlights
Paddy rice (Oryza sativa L.) is the main cultivated crop worldwide [1]
A related investigation revealed that the fluorescence peak at 685 nm was attributed to chlorophyll a, which is associated with photosystem II
The possible interpretation for this is that the fluorescence emitted between 684 and 695 nm was more strongly reabsorbed by the chlorophyll pigment than that between 730 and 745 nm in the upper layer leaf cells [26]
Summary
Paddy rice (Oryza sativa L.) is the main cultivated crop worldwide [1]. Nitrogen (N) is known to be one of the required elements for the growth of paddy rice, so farmers tend to increase the dose of N fertilizer to improve paddy rice yield. N fertilizer abuse, which has resulted in serious environmental problems, has attracted much attention throughout the world. Passive remote sensing, which can measure the spectral information of paddy rice, was used as a main method.
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