Responses of rice leaf thickness,SPAD readings and chlorophyll a/b ratios to different nitrogen supply rates in paddy field |
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Authors: | Li Jinwen Yang Jingping Fei Pinpin Song Junlan Li Dongsheng Ge Changshui Chen Wenyue |
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Institution: | 1. College of Life Sciences, Zhejiang University, Kaixuan Road, Hangzhou 310029, China;2. College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310029, China;3. College of Measurement and Test Engineering, China Jiliang University, Hangzhou 310018, China;4. Hangzhou Academy of Agricultural Sciences, Hangzhou 310003, China |
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Abstract: | The objective of this paper was to investigate the influence of different nitrogen (N) application rates to some morphological and physiological features of leaf blades, including leaf thickness, chlorophyll content at different leaf ages and chlorophyll a/b ratios. A paddy field and a cement tank experiments were conducted simultaneously. Rice leaf thickness was measured through a specially developed displacement sensor. Meanwhile, chlorophyll content was estimated using chlorophyll meter (SPAD) and spectrophotometer after ethanol extraction of leaf samples. With the increase of N application, leaf thickness became thinner and chlorophyll a/b ratios decreased. Moreover, the sensitivity of the SPAD readings of the same leaf at different leaf ages to N rates was assessed through coefficients of variation (CV). CV of SPAD readings increased from 8.8% to 21.6% during leaf lifetime, which indicates that SPAD readings became more and more sensitive to nitrogen rates as leaf aged. Therefore, SPAD readings of the lower leaves, which were physiologically older than the upper ones, were more sensitive to nitrogen rates. |
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Keywords: | Specific leaf mass Nitrogen Leaf thickness |
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