Morphological charateristics of the root system of Japonica-Indica hybrid rice cultivars

Nutrient requirements for single-season rice using the quantitative evaluation of the fertility of tropical soils (QUEFTS) model in China have been estimated in a previous study, which involved all the rice varieties; however, it is unclear whether a similar result can be obtained for different rice varieties. In this study, data were collected from field experiments conducted from 2016 to 2019 in Zhejiang Province, China. The dataset was separated into two parts: japonica/indica hybrid rice and japonica rice. To produce 1000 kg of grain, 13.5 kg N, 3.6 kg P, and 20.4 kg K were required in the above-ground plant dry matter for japonica/indica hybrid rice, and the corresponding internal efficiencies (IEs) were 74.0 kg grain per kg N, 279.1 kg grain per kg P, and 49.1 kg grain per kg K. For japonica rice, 17.6 kg N, 4.1 kg P, and 23.0 kg K were required to produce 1000 kg of grain, and the corresponding IEs were 56.8 kg grain per kg N, 244.6 kg grain per kg P, and 43.5 kg grain per kg K. Field validation experiments indicated that the QUEFTS model could be used to estimate nutrient uptake of different rice varieties. We suggest that variety should be taken into consideration when estimating nutrient uptake for rice using the QUEFTS model, which would improve this model.

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Effects of nitrogen application rate on the photosynthetic pigment, leaf fluorescence characteristics, and yield of indica hybrid rice and their interrelations

Scientific Reports ◽

10.1038/s41598-021-86858-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jinfeng Peng ◽

Yuehua Feng ◽

Xiaoke Wang ◽

Jie Li ◽

Guiling Xu ◽

...

Keyword(s):

Quantum Yield ◽

Hybrid Rice ◽

Photosynthetic Pigment ◽

Application Rate ◽

Maturity Stage ◽

Nitrogen Application ◽

Fluorescence Characteristics ◽

Heading Stage ◽

Indica Hybrid Rice ◽

Nitrogen Application Rate

AbstractA field experiment employing the rice cultivars Qyou6 and Yixiangyou2115 as materials and different nitrogen application rates was conducted in Huangping County, Guizhou Province in 2019 to determine the effects of nitrogen application rate on photosynthetic pigments, leaf fluorescence characteristics, yield, and their interrelations in indica hybrid rice. The results showed that photosynthetic pigment contents generally increased with increasing nitrogen application rate. As the nitrogen rate increased, the maximal quantum yield of PSII (Fv/Fm), actual quantum yield of PSII (ΦPSII), and relative electron transfer rate at PSII (ETR) first decreased and then increased at the booting stage; Fv/Fm and ΦPSII decreased while ETR first increased and then decreased at the heading stage; nevertheless, Fv/Fm and ΦPSII first decreased and then increased but ETR was just the opposite at the maturity stage. Non-photochemical quenching coefficient (qN) and quantum yield of regulatory energy dissipation at PSII (Y(NPQ)) first increased and then decreased whereas quantum yield of non-regulatory energy dissipation at PSII (Y(NO)) first decreased and then increased at the booting, heading, and maturity stages with increasing nitrogen application rate. Photochemical quenching coefficient (qP) showed an increasing trend as the nitrogen rate increased in the range of 150–300 kg/ha at the heading and maturity stages. Photosynthetic pigments, leaf fluorescence characteristics, and yield and its components were significantly correlated. First, chlorophylls a and b were significantly negatively correlated with Fv/Fm while significantly positively correlated with qP at the heading stage. Secondly, Carotenoids were significantly positively correlated with the effective panicle number (EPN) at the booting stage while significantly negatively correlated with the spikelets per panicle (SPP) at the heading stage. Chlorophyll a and carotenoids were significantly positively correlated with EPN but significantly negatively correlated with spikelet filling (SF) at the maturity stage. In addition, qP was significantly negatively correlated with EPN at the booting stage. At the heading stage, Fv/Fm and Y(NO) were significantly negatively correlated with EPN and SPP, respectively, and Fv/Fm and ΦPSII were significantly positively related to SF. Moreover, qP was extremely significantly positively related to EPN whereas Fv/Fm was extremely significantly negatively correlated with grain yield at the maturity stage. Appropriate nitrogen application rates can enhance photosynthetic pigment contents, improve the photochemical efficiency and proportion of the open part of the reaction center of PSII, and promote the quantum efficiency and self-protection ability of PSII, thereby increasing photosynthetic efficiency and yield. Under the conditions adopted in this experiment, a parabolic relationship was observed between the nitrogen application rate and grain yield. The regression analysis results showed that the best nitrogen application rate of indica hybrid rice is 168.16 kg ha−1 and the highest yield is 11,804.87 kg ha−1.

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Monitoring Hybrid Rice Phenology at Initial Heading Stage Based on Low-Altitude Remote Sensing Data

Remote Sensing ◽

10.3390/rs13010086 ◽

2020 ◽

Vol 13 (1) ◽

pp. 86

Author(s):

Yi Ma ◽

Qi Jiang ◽

Xianting Wu ◽

Renshan Zhu ◽

Yan Gong ◽

...

Keyword(s):

Remote Sensing ◽

Air Temperature ◽

Hybrid Rice ◽

Remote Sensing Data ◽

Rice Cultivars ◽

Sensing Data ◽

Gauss Function ◽

Low Altitude ◽

Rice Phenology ◽

Heading Stage

Accurate monitoring of hybrid rice phenology (RP) is crucial for breeding rice cultivars and controlling fertilizing amount. The aim of this study is to monitor the exact date of hybrid rice initial heading stage (IHSDAS) based on low-altitude remote sensing data and analyze the influence factors of RP. In this study, six field experiments were conducted in Ezhou city and Lingshui city from 2016 to 2019, which involved different rice cultivars and nitrogen rates. Three low-altitude remote sensing platforms were used to collect rice canopy reflectance. Firstly, we compared the performance of normalized difference vegetation index (NDVI) and red edge chlorophyll index (CIred edge) for monitoring RP. Secondly, double logistic function (DLF), asymmetric gauss function (AGF), and symmetric gauss function (SGF) were used to fit time-series CIred edge for acquiring phenological curves (PC), the feature: maximum curvature (MC) of PC was extracted to monitor IHSDAS. Finally, we analyzed the influence of rice cultivars, N rates, and air temperature on RP. The results indicated that CIred edge was more appropriate than NDVI for monitoring RP without saturation problem. Compared with DLF and AGF, SGF could fit CIred edge without over fitting problem. MC of SGF_CIred edge from all three platforms showed good performance in monitoring IHSDAS with good robustness, R2 varied between 0.82 and 0.95, RMSE ranged from 2.31 to 3.81. In addition, the results demonstrated that high air temperature might cause a decrease of IHSDAS, and the growth process of rice was delayed when more nitrogen fertilizer was applied before IHSDAS. This study illustrated that low-altitude remote sensing technology could be used for monitoring field-scale hybrid rice IHSDAS accurately.

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