Estimation of Garlic’s Bulb Weight at Harvest Using a Multi-level Model Based on Growth and Meteorological Data

There is a large fluctuation in the production and price of garlic (Allium sativum L.) because it is grown mainly in the open field and is vulnerable to weather conditions. Accurate forecasting is needed to manage production. The purpose of this study was to improve the accuracy of production forecasting by developing a model that estimates the weight of garlic bulbs at harvest based on growth and meteorological data. For this study, a two-level multilevel model was used to reflect the hierarchical data characteristics consisting of individual unit data that represented the above-ground growth conditions at the end of April and the lot unit data that represented the meteorological conditions from the end of April to harvest time. It was determined that the weight of the garlic bulb increased as the growth of the sheath diameter and the plant height increased at the end of April. As for the meteorological factors, it was estimated that precipitation had negative effects on the garlic bulb weight, while the pre-harvest precipitation, duration of sunshine, evapotranspiration, and the optimal temperature days had positive effects on the weight. Additional key words: Allium sativum L., fixed effect, growth observation survey, hierarchical data, supply-demand management