growing period calculation and net biomass production estimation of sugar beet by fao growth model in lorestan silakhoor plain

this study was carried out in lorestan silakhoor plain  during 2001-2002. twenty soil properties from 25 profiles were evaluated. profiles studied were entisols and inceptisols. moreover, soil classification resulted in 5 subgroups, 8 families and 17 soil series. in the study, parametric land evaluation method was used. the strong correlation between the land index and observed yield (r = 0.55) suggested the potential usefulness and applicability of the parametric land evaluation method. the area is located in semiarid region, based on broujerd station data. the objective of this research was to determine the growing period and radiation thermal production potential (rtpp) for sugar beet. the results indicated that growing period of sugar beet in the area starts on 6 november and ends on 3 may, which is about 179 days, and rtpp is 68628 kg/ha. average sugar beet yield in the research area was 28448 kg/ha (1991-2001) with an average of 14.72% sugar content (min. 13.78%, max. 16.28%) based on lorestan sugar beet factory data. the net biomass production was calculated using climatic and crop data and predicted yield was obtained from the effects of soil, water and management limitations on rtpp. therefore, observed yield can be increased by removing remediable soil limitations and promoting management level.