Analysis of the influence of environmental variables on carbon content of sugar beet crop and estimation of nitrogen content in leaves by vegetation indices

Resumen

In the first article, entitled “Impact of Climate Variables on Carbon Contents in Sugar Beet Root” the impact of climate variables on the growth and carbon contents of spring-sown sugar beet (Beta vulgaris saccharifera) in Castilla y Leon region (north-western Spain) was assessed by analysing 34 beet crop parameters at different sites over two years. By resorting to ANOVA, Principal Component Analysis and Cluster Analysis, the impact of different factors such as climatic variables, site, beet variety or fertilization was evaluated. In the second article entitled “Assessment of The Use of RGB Vegetation Indices to Determinate Chlorophyll Content in Sugar Beet Leaves at Final Cultivation Stage” introduce the fact that high nitrogen levels in sugar beet leaves detected in the growing final stage can be an indicator of late incorporations of nitrogen from organic matter from soils or fertilizers. These tardy uptakes are known to decrease sugar yields. Thus, Among the different ways to measure nitrogen status in crops, here chlorophyll content determination using vegetation indices is explored. In this study, pictures of sugar beet leaves taken with a commercial camera were used to calculate 25 RGB indices found in bibliographic review and to obtain two new indices. The performance of studied indices are examined to evaluate its ability to measure chlorophyll content and degradation for sugar beet leaves in different natural light conditions along 4 days at final cultivation stage. In the short communication named “Detection of Sinapis arvensis Weeds in Alfafa Crop by Using RGB Indices” based on the good correlations shown by R-B/R+B and R-B/R+B+G at leaf scale for sugar beet leaves, considering that the colour rank in that study was from dark green to yellow, it was proposed to use these indices for checking its possible utility in detection of yellow weeds in fields of green crops. So in the frame of European LIFE Project Operation CO2 yellow weeds (Sinapis arvensis) infection occurred in alfalfa crop (Medicago sativa) plots sited in the experimental parcel of Soto de Cerrato (Palencia, Spain) which belongs to University of Valladolid. Thus images from UAV were used to make a mosaic from which were calculated R-B/R+B, R-B/R+B+G and NDVI index for visual comparison. In the third article entitled “Regional Analysis of Sugar Beet Crop under Future Scenarios of Climate Change” Evapotranspiration (ET) is studied as a main factor affecting crop yields which is related to water requirements of the plants. Because of changes predicted in future global climate it is necessary to assess the effects of different environmental conditions in crops such as sugar beet, which depend on irrigation to obtain high yields, in order to foresee measurements of adaptation. In the study presented herein future conditions extracted from RCP4.5 scenario of IPCC for 2050 and 2070, in Spanish region of Castilla y León, were used as inputs of FAO crop simulation model (Aquacrop). Thus, a regional analysis of future trends in yields, biomass and CO2 assimilation of sugar beet crop are carried out and adaptation measurements are also proposed.