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Agriculture & Soil
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The method and practice of macro Remote Sensing Monitoring of winter wheat
The experimental results show that logarithmic function is fit for PVI an LAI before earing stage. Please see the Fig.1 the value of LAI will reach its climax at earing stage (LAImax). If we call LAI/LAImax standard leaves area index (LAIn), the a universal law of LAIn (t) does exist which is mainly controlled by day temperature accumulation. One stem has one ear, so LAImax keeps linear function with ear number. Therefore the ear number can be judged by measurement of PVI corresponding day _ temperature accumulation. One stem has one ear, so LAImax keeps linear function with ear number. Therefore the ear number can be judged by measurement of PVI and corresponding day temperature accumulation data. The logical relation can be expressed by
because of the emphasis of biomass increasing to be put on leaf's growing, so the effect of different environmental factors or different agronomic measures are totally reflected by value of LAI. Therefore it is necessary to consider to other factors when we juged S by PVI, sometimes it is practical to form an empirical formular such as
S= Aeb PVI dt
experimental results show the weight of stem per unit length is closely related with grain number and grain weight, it is obvious that ear number is determined by colony, but the grain number and grain weight are decided by robustness of individual. If PVI describs the effective photosynthetic intensity of individual. The organ of grain was built from jointing stage to flowering stage to be fixed at this time. The grain weight will be determined by strength of milking and its duration. It begins at flowering stage lasting to ripe stage.
Winter wheat absorbs water from its root system, 99% water absorbed to be evaporated into atmosphere through leaves. The function of water keeps smooth transportation of material inside the body and makes cavities on the leaves open properly and let enough amount of CO2 coming, so soil moisture (Vw) becomes one of the factors to form grain number and grain weight.
Since the main stem to grow up early, it has enough time and nutrition to form big ear. The later the tillering happen, the higher location the tillering stems grew up, the lower possibility the big ear have. So the effective tillering number (T) is also one of the factors to form grain number (L).
For every sample field a linear equation may be constructed by grain number (L), PVI/S, Vw and T. For many sample fields a group of this kind linear equation can be formed. The pseudoinvers method was employed to calculate weight coefficient (a1, a2, a3).
L = a1 ( ò2 PVI.dt / s) + a2Vw + a3T --------------------(1)
The same way can be used for grain weight
Z = b1 ( ò3 PVT.dt/S) + b2Vw ---------------------------(2)
In our
experiments every sample field is under the same temperature and insolation. If we use <1> and <2> tio practical situation, the first term PVI dt/S must be multiplied by mending factor of insolation hours.
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