However, the maximum number of fruit clusters available for harvest is limited by the number of inflorescences initiated in those buds during the previous growing season. The upper limit on the number of fruitful shoots per vine is largely determined by the number of buds left after winter pruning-that is, on the pruning severity. Vine size in turn depends on the planting density, as well as on the trellis and training system and the pruning method (e.g., spur, cane, mechanical, or minimal). The vineyard yield is the sum of the yield of all individual vines and depends on the planted land surface, the number of bearing vines per unit land area, and the size of each vine. Yield = buds vine × shoots bud × clusters shoot × berries cluster × berry weight The concept of crop load is similar to the concept of harvest index used in cereals and other crops the harvest index is defined as the amount of harvested product relative to the total above-ground biomass. “Overcropping” refers to the production of more crop than a vine can bring to acceptable maturity by normal harvest time (see Section 6.2). Vine size is usually estimated as pruning weight or leaf area thus, crop load is a measure of the canopy sink ÷ source ratio and is often called “vine balance” by viticulturists. By contrast, the term “crop load” refers to the crop size relative to vine size. The terms crop level and crop size are often used synonymously. The “crop level” is the amount of fruit (sometimes the number of clusters) per shoot or per unit of canopy length, the “crop size” is the yield per vine or per unit of land area. Yield formation is often referred to as cropping, with the crop being the amount of fruit borne on a vine or produced by a vineyard. Viticultural yields are determined by the amount of sugar partitioned to the fruit rather than to other organs. The amount of fruit production in a given year and over the lifetime of grapevines determines both their reproductive success as a species and their agronomic trait of yield potential. Markus Keller, in The Science of Grapevines (Third Edition), 2020 6.1.1 Yield components and compensation The analysis may be performed by linking the simulation model with a Geographic Information System to define the ideotypes for different areas within a region. Future work should also explore the effect of rotations and fertilizer management on the performance of sunflower genotypes differing in EV and season length. The physiological bases of differences in EV remain unknown and deserve further research. This analysis may be extended to determine the optimum sunflower season length at any environment taking into account soil and weather data. In the cases studied, medium season length genotypes produce the maximum yield, except for a late sowing date on shallow soil, when short genotypes performed the best. The optimum strategy would be to use the genotype with a season length adequate for a given environment and with high EV. Higher yield was related to higher EV for every environment studied as a result of increases in WUE, the T/ET ratio and TE. Using a modified version of OILCROP-SUN to analyze the effect of EV on sunflower yield under different situations we concluded that high EV is a positive character. Thus, selection for high EV in a sunflower breeding program to improve seed yield will not be correlated with indirect selection for a poor rooting system or a short season length. We can find plants with high EV and a determined season length. Moreover, the negative association between EV and season length does not imply substantial differences between plants with high and low EV. High EV in sunflower populations is not related to a low dry matter accumulation in the root. Orgaz, in Developments in Crop Science, 1997 5 Conclusions
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