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Summer maize was used as the research object, firstly, ground hyperspectral data were obtained for four key fertility stages（pulling stage, trumpeting stage, tasseling stage, filling stage）, and the above-ground biomass（AGB） of each fertility stage was measured empirically. Secondly, waveband optimization algorithms based on arbitrary waveband combinations were constructed for six different waveband combination forms of two-band and three-band spectral indices, respectively. Then, the 12 constructed spectral indices were correlated with the ground-truthed AGB, from which the best correlated spectral index was selected as the optimal spectral index to construct the AGB estimation model for summer maize at full fertility. Finally, the performance of the optimal spectral index for estimating AGB at each critical fertility stage of summer maize was systematically evaluated. The results showed that the optimal three-band spectral index TBI6（760,925,895） screened based on the band optimization algorithm had good correlation with the AGB of summer maize at all fertility stages and the whole fertility period, and the AGB estimation model constructed by it had high accuracy, which could provide a reference for the rapid and nondestructive estimation of AGB of summer maize at the whole fertility period and the integration and development of AGB monitoring devices. [ABSTRACT FROM AUTHOR]

Objectives: The key phenological information of oilseed rapeseed (Brassica napus L.) plays an important role in field management, viewing time prediction and yield estimation of the oilseed rape. It is also an important part of precision agriculture. Polarimetric synthetic aperture radar technology shows great potential in phenological phase identification with its all-weather monitoring capability and its sensitivity to the crop structural information. Methods: First, we identified the 5 phenological phases of the oilseed rape on the test area with 5 time series full-polarization Radarsat-2 data, which covers the whole growth period of the oilseed rape. 6 typical Stokes parameters are extracted and applied in the identification of oilseed rape phenological phases, the extracted Stokes parameters includ averaged intensity(g0), normalized average intensity(g0m), averaged degree of polarization(ρm), perimeter degree of zero orientation route(Pdor),inclination degree of zero aperture route(Idap), and arc asymmetry degree of zero aperture route(Aadap). Then, The phenological phases of oilseed rape is identified by the decision tree (DT) algorithm based on the comparative analysis of the dynamic response of the 6 special Stokes parameters to rape growth stages. Results and Conclusions: Among the extracted Stokes parameters applied in this study, except ρm and Aadap, other parameters show great sensitivity to the change of the oilseed rape phenological phases. The DT algorithm also perform well in the classification of the oilseed rape phenological phases. The classification results agree well with the field measured samples, and the overall classification accuracy is 87.4%, while the highest classifi⁃ cation accuracy of each phenological phase is 94.3%. [ABSTRACT FROM AUTHOR]

[ Objective] The study aimed to provide a scientific theoretical basis for the selection of superior province of lacquer tree. [ Method] In this study, photosynthetic characteristics of three geographic provinces from Hubei, Shaanxi and Yunnan were measured, and net photosynthetic rate, stomatal conductance, intercellular CO2 concentration and transpiration rate indexes of different province were measured. The differences of photosynthetic index, utility rate of luminous energy and water use efficiency of different provinces were analyzed. [ Result] The results showed that the photosynthetic characteristics of the three province seedlings showed certain regularity: the net photosynthetic rate ( Pn) and stomata! conductance ( Gs) of the seedlings were in turn as Hubei province >Yunnan province > Shaanxi province. The transpiration rate ( Tr) of Shaanxi province was the largest in the three province, while the water use efficiency of Yunnan province was the highest, but the average comprehensive utilization of water was the best in Hubei. The diurnal variation of the permeability in every province was uniformity. The lacquer seedlings had obvious photosynthesis midday break phenomena. [ Conclusion] Therefore, according to the photosynthetic characteristics, some measures of appropriate shading could be carried out during seedling cultivation to promote seedling growth. Of which, the utilization rates of light energy in Badong Hubei province were high which reflected the good growth of the seedlings and the adaptation to the environment to a certain extent, and should further carry out for genetic improvement and support the high-yield cultivation of the lacquer forest. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar (SAR) has been proved as an effective tool for agricultural monitoring and its effectiveness depends on the accurate and appropriate interpretation of SAR Information. Stokes pa⁃ rameters, which is proposed on the dichotomy principle of electromagnetic wave, describe the changes of the incident electromagnetic wave affected by objects which are radiated by electromagnetic wave, and then obtain the information from the objects. However, to our best knowledge, few reports focus on crop phenology monitoring using Stokes parameters. This study aims to explore the feasibility of Stokes related parameters for crop growth monitoring. In this paper, Stokes parameters and their subparameters are calcu⁃ lated based on assumption of wave transmitted in horizontal and received in both horizontal and vertical po⁃ larization. Then these Stokes parameters are derived from 5 multi⁃temporal Radarsat⁃ 2 images and aver⁃ aged relying on each oilseed rape field area. The correlation between all of the Stokes parameters and oil⁃ seed rape growth parameters including above ground biomass (AGB), height and leaf area index (LAI) are computed by Pearson product moment correlation coefficient. The significance of these Stokes parameters for oilseed rape AGB, height and LAI inversion are derived from random forest (RF) model. The results in⁃ dicate the potential of Stokes parameter for crop growth monitoring and growth parameters inversion. It demonstrates that scattering power related Stokes parameters reveal better performance for crop AGB in⁃ version, but scattering mechanism related Stokes parameters such as degree of polarization (m), the degree of linear polarization (ml) and the ratio of linear polarization (μl) are more sensitive to crop height and LAI. Moreover, the results suggest that it is necessary to analyze the influence of crop structure on scattering power when crop growth parameters inversion is performed with Stokes parameters. [ABSTRACT FROM AUTHOR]