Estimating aboveground and organ biomass of plant canopies across the entire season of rice growth with terrestrial laser scanning     

《International Journal of Applied Earth Observation and Geoinformation》2020

Non-destructive and accurate estimation of crop biomass is crucial for the quantitative diagnosis of growth status and timely prediction of grain yield. As an active remote sensing technique, terrestrial laser scanning (TLS) has become increasingly available in crop monitoring for its advantages in recording structural properties. Some researchers have attempted to use TLS data in the estimation of crop aboveground biomass, but only for part of the growing season. Previous studies rarely investigated the estimation of biomass for individual organs, such as the panicles in rice canopies, which led to the poor understanding of TLS technology in monitoring biomass partitioning among organs. The objective of this study was to investigate the potential of TLS in estimating the biomass for individual organs and aboveground biomass of rice and to examine the feasibility of developing universal models for the entire growing season. The field plots experiments were conducted in 2017 and 2018 and involved different nitrogen (N) rates, planting techniques and rice varieties. Three regression approaches, stepwise multiple linear regression (SMLR), random forest regression (RF) and linear mixed-effects (LME) modeling, were evaluated in estimating biomass with extensive TLS and biomass data collected at multiple phenological stages of rice growth across the entire season. The models were calibrated with the 2017 dataset and validated independently with the 2018 dataset.The results demonstrated that growth stage in LME modeling was selected as the most significant random effect on rice growth among the three candidates, which were rice variety, growth stage and planting technique. The LME models grouped by growth stage exhibited higher validation accuracies for all biomass variables over the entire season to varying degrees than SMLR models and RF models. The most pronounced improvement with a LME model was obtained for panicle biomass, with an increase of 0.74 in R² (LME: R² = 0.90, SMLR: R² = 0.16) and a decrease of 1.15 t/ha in RMSE (LME: RMSE =0.79 t/ha, SMLR: RMSE =2.94 t/ha). Compared to SMLR and RF, LME modeling yielded similar estimation accuracies of aboveground biomass for pre-heading stages, but significantly higher accuracies for post-heading stages (LME: R² = 0.63, RMSE =2.27 t/ha; SMLR: R² = 0.42, RMSE =2.42 t/ha; RF: R² = 0.57, RMSE =2.80 t/ha). These findings implied that SMLR was only suitable for the estimation of biomass at pre-heading stages and LME modeling performed remarkably well across all growth stages, especially for post-heading. The results suggest coupling TLS with LME modeling is a promising approach to monitoring rice biomass at post-heading stages at high accuracy and to overcoming the saturation of canopy reflectance signals encountered in optical remote sensing. It also has great potential in the monitoring of other crops in cloud-cover conditions and the instantaneous prediction of grain yield any time before harvest.  相似文献   

SO2污染环境下水稻导数光谱与生理生化指标的相关性研究     

张金恒  李曰鹏  韩超  张振华 《国土资源遥感》2008,19(4):43-46

通过田间开顶式小区熏气试验,研究在SO2急性伤害条件下水稻冠层导数光谱与叶片含硫量、叶液pH值以及叶绿素含量的相 关性。分别选择分蘖期和抽穗期显著相关的波段(分蘖期： 689 nm、584 nm、570 nm; 抽穗期： 689 nm、584 nm、585 nm)建立 预测叶片含硫量、叶液pH值及叶绿素含量的回归模型,并分别用拔节期和灌浆期相应导数光谱反射率检验模型预测精度。结果表明 ,由分蘖期建立的回归模型估测拔节期叶液pH值以及叶绿素含量与实测值之间相关系数分别为0.884和0.630; 由抽穗期建立的回 归模型估测灌浆期的叶片含硫量、叶绿素含量与实测值之间相关系数分别为0.659和0.768,均通过显著检验。  相似文献   

Wavelength selection and spectral discrimination for paddy rice, with laboratory measurements of hyperspectral leaf reflectance   总被引：1，自引：0，他引：1  

Shalei Song  Wei GongBo Zhu  Xin Huang 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(5):672-682

The objective of this research is to select the most sensitive wavelengths for the discrimination of the imperceptible spectral variations of paddy rice under different cultivation conditions. The paddy rice was cultivated under four different nitrogen cultivation levels and three water irrigation levels. There are 2151 hyperspectral wavelengths available, both in hyperspectral reflectance and energy space transformed spectral data. Based on these two data sets, the principal component analysis (PCA) and band-band correlation methods were used to select significant wavelengths with no reference to leaf biochemical properties, while the partial least squares (PLS) method assessed the contribution of each narrow band to leaf biochemical content associated with each loading weight across the nitrogen and water stresses. Moreover, several significant narrow bands and other broad bands were selected to establish eight kinds of wavelength (broad-band) combinations, focusing on comparing the performance of the narrow-band combinations instead of broad-band combinations for rice supervising applications. Finally, to investigate the capability of the selected wavelengths to diagnose the stress conditions across the different cultivation levels, four selected narrow bands (552, 675, 705 and 776 nm) were calculated and compared between nitrogen-stressed and non-stressed rice leaves using linear discriminant analysis (LDA). Also, wavelengths of 1158, 1378 and 1965 nm were identified as the most useful bands to diagnose the stress condition across three irrigation levels. Results indicated that good discrimination was achieved. Overall, the narrow bands based on hyperspectral reflectance data appear to have great potential for discriminating rice of differing cultivation conditions and for detecting stress in rice vegetation; these selected wavelengths also have great potential use for the designing of future sensors.  相似文献   

Of yield gaps and yield ceilings: Making plants grow in particular places     

《Geoforum》2014

The System of Rice Intensification (SRI) and rice genetic improvement are proposed as two approaches to improving and increasing rice production. In recent exchanges, they have been represented by their respective supporters as starkly contrasting, almost mutually incompatible alternatives. However, advocates on both sides of this argument have tended to stress the genetic and physiological characteristics of rice plants and place less emphasis on the spatially and temporally situated knowledge and management skills of farmers, which are the means by which any agricultural technology is locally adapted and integrated into livelihood strategies, and technological potential is translated into real outcomes in specific settings. Taking this proposition seriously would entail a substantial reorganisation of agricultural research and extension, bridging the historical divide between these two wings of professional agronomy. It would require agronomists of both types to work more collaboratively with farmers. It would also require scientists to produce new kinds of outputs, such as analytical frameworks, heuristics and decision-making tools to help farmers apply scientific insights to their own constrained circumstances. This argument is made with reference to the cases of SRI (a cultivation system that is said to boost farm yields without the need for genetically improved germplasm) and C4 rice (a crop-improvement project intending to ‘supercharge’ rice photosynthesis to increase rice yields). The paper uses the agronomic concepts of the ‘yield gap’ and the ‘yield ceiling’ to offer a perspective on strategic questions about the goals and organisation of agricultural research and extension.  相似文献   

Nitrogen Fertilizer Optimization and Cultivar Selection for Rice Grown near Mountainous Slopes in Orissa, India ——A Field Experiment and Simulation Model Study     

D. K. Swain  S. Herath  A. Pathirana  R. N. Dash 《山地科学学报》2005,2(4):329-335

Introduction Agriculture, which is the dominant sector in the mountains, is generally stagnant. Degradation of the natural resource base has contributed to an increase in frequency and intensity of landslides, gully formation, soil erosion, declining soil fertility, reduced per capita availability and fragmentation of land, and reduced flow of water for irrigation. This has led to steady decline in crop yields (5~30 %) or stagnation that caused food shortages at varying degrees among mountain …  相似文献   

东北地区水稻霜冻灾害风险评估与区划   总被引：1，自引：0，他引：1  

王晾晾  杨晓强  李帅  朱海霞  王萍  纪仰慧  姜丽霞 《辽宁气象》2012,(5):40-45

依据灾害系统理论,在综合考虑致灾因子自然属性和承灾体社会属性的基础上,建立风险评估模型,将传统的灾害研究方法与地理信息系统等现代技术手段相结合,利用1961—2010年东北地区182个气象站点逐日最低气温资料和1991—2006年172个水稻产区县（市）国土面积及社会经济资料,包括1981—2006年30个农业气象观测站水稻发育期资料,对东北地区水稻霜冻灾害风险进行评估。结果表明：东北地区可划分为高风险、次高风险、中等风险、次低风险和低风险5个水稻霜冻灾害风险区域。东北地区水稻霜冻灾害高风险区位于黑龙江省的黑河地区大部、伊春西部和吉林省的延边州西部、白山北部等地,而辽宁省的中南部等地风险较低。  相似文献   

连云港水稻产量的气象影响因子分析   总被引：1，自引：1，他引：0  

肖卉  沈瑱  刘杰  翟伶俐 《气象科学》2012,32(S1):81-86

经验正交函数分析方法(EOF)是正交函数分解方法的一种,其优点是可将某要素场分解为不随时间变化的空间函数部分的特征向量及与空间无关的时间函数部分。该方法同样可用于某空间点的多要素特征分析,得到的空间函数每个特征向量都反映了所有要素某种共性。本文则是利用EOF这一特性,选取连云港地区历年(1961—2007年)水稻各个生育期的多个气象因子与气象产量做EOF分析,选取方差贡献大的前4项特征向量中与产量相关性较好的因子,作为影响因子。并通过对影响因子多年变化趋势及波动特征年的分析,剔除其相关性差的因子,最终得到与产量密切相关的气象因子。  相似文献   

Silicon transfers in a rice field in Camargue (France)     

V. Desplanques  L. Cary  J.-C. Mouret  F. Trolard  G. Bourri  O. Grauby  J.-D. Meunier 《Journal of Geochemical Exploration》2006,88(1-3):190

We conducted a study of the biogeochemical cycle of silicon in a rice field in Camargue (France) in order to evaluate the role of biogenic silicon particles (BSi) in the cycle. Opal-A biogenic particles (phytoliths, diatoms…), which dissolve more rapidly than other forms of silicate usually present in soils, are postulated to represent the easiest bioavailable Si for rice. We found 0.03–0.06 wt.% of BSi in soils (mainly phytoliths). This value is lower than other values from the literature. Each year, the exportation of BSi from rice cultivation is 270 ± 80 kg Si ha^− 1. We show that BSi input by irrigation is mostly composed of diatoms and we estimate it at 100 kg Si ha^− 1 year^− 1. This value is more than a third of the annual Si need for rice. The budget of the dissolved silicon (DSi) fluxes gives the following results: the atmospheric and irrigation inputs represents 1% and roughly 10%, respectively, of the annual need for rice; the drainage and infiltration outputs represent 17 ± 14 and 12 ± 9 kg Si ha^− 1 year^− 1, respectively; the balance of our budget shows that at least 170 kg Si ha^− 1 year^− 1 are exported from the soil. If we consider the soil BSi as the only source of dissolved silicon, this stock could be exhausted in 5 years.  相似文献   

2005年江西晚稻飞虱大发生气象成因初步分析   总被引：7，自引：0，他引：7  

杜筱玲  郭瑞鸽  魏丽 《气象与减灾研究》2006,29(2):48-52

介绍了江西省稻飞虱历年发生概况,以及2005年江西稻飞虱发生特点,并从2005年副高脊线位置与飞虱早迁、汛期降雨峰值与飞虱多迁、台风环流与飞虱秋季回迁、夏秋季温湿条件与飞虱生长繁殖的关系等方面,进行了稻飞虱大发生的气象成因分析,力图为今后建立稻飞虱发生发展气象预测模型,开展灾害监测与预报提供依据.分析结果表明,2005年江西省晚稻飞虱具有发生时间早、面积广、为害重等特点,为历史罕见大爆发;稻飞虱主要来源于外地迁入,有春季迁入及秋季回迁2种;副高脊线位置偏南,西南气流强盛,导致春季气候适宜,暖湿气流活跃,强降水多,有利春季稻飞虱早迁、多迁、大量迁,早稻发生后的残留虫量是晚稻飞虱大发生的虫源基础;7～10月台风频频影响江西,特别是后期台风的影响,加速了秋季稻飞虱随东北气流的回迁,为晚稻飞虱大爆发起到促进作用;盛夏不热且秋季不凉的气象条件,有利于当地稻飞虱的生长繁殖,导致飞虱代数多.  相似文献   

应用数值模拟进行水稻品种的丰产性鉴定          下载免费PDF全文

李军  吴元中 《应用气象学报》1997,8(3):374-378

应用单叶光合作用非线性双曲线光响应模型，在生产上进行水稻品种丰产性鉴定。结果表明在上海地区测定的水稻品种中，“寒优湘晴”的丰产性最好。  相似文献