ADAPTATION OF A MODEL TO EVALUATE SEED DETERIORATION IN HUSK TOMATO

Abstract

Air temperature and relative humidity are the most important environmental factors affecting the viability of stored seeds. In this investigation, the viability of husk tomato (Physalis ixocarpa Brot.) seeds stored without control of air temperature and relative humidity, was estimated with a model designed for tomato seeds (Lycopersicon esculentum Mill.). The seed moisture was calculated using the air temperature and relative humidity of storage conditions, while the seed viability was calculated using the Ellis and Roberts equation. The coefficient lambda (λ) in the seed water content equation, and the values of C_H, C_W, C_Q, and Ki in the Ellis and Roberts equation were calibrated with the Marquardt and Simplex optimization methods. The mean error of the difference between observed and modeled data (MBE), the mean error in percent (MPE), and the root square of the mean difference between modeled and observed data (RMSD), were used as bias measurements. The calibrated lambda (61.6) for husk tomato seeds was 62 % higher than that for tomato, but this calibrated value rendered an adequate average (5 %) of the seed moisture. C_H, C_W and K_i optimized simultaneously with the Simplex method produced the best calibration of the Ellis and Roberts equation, since each parameter changed less than 4.6 % from its original value, with a mean error of 3.4 % and a R² over 0.97. Modeled viability of husk tomato seeds was higher or equal than 85 % after 263 d of storage, and there after 50 % of viability was lost in 4 years and 5 months.