The effect of temperature during fruit development on the quality of green snap beans

The effect of temperature and maturity on the quality of Tendercrop green snap beans was studied by growing plants in controlled environment cabinets. Plants were grown in the greenhouse until 7 days after anthesis at which time they were removed and transferred to temperatures of 20°C, 25°C, 30°C and 35°C. The beans were harvested at 14, 19, 21, 29 and 34 days after anthesis and analyzed for various quality factors. Growing the fruit at a temperature of 35°C resulted in a significant stunting of the size and average weight of the pod. The optimum temperature for maximum yield was found to be 25°C. Temperature resulted in a significant increase in lightness and yellowness and increased significantly with maturity below 35°C over the period studied. Toughness did not change with maturity or temperature between 20°C and 30°C until 24 days after anthesis. After this point, toughness increased with increasing temperature. Beans grown at 35°C were significantly tougher than 20 - 30°C beans and increased in toughness over their 14 - 24 day maturity period. Increased temperature and maturity caused an increase in total solids, water insoluble solids, starch, fibre and in pectin above 30°C. Total sugars decreased with maturity and increased temperature. Total ash did not change significantly with temperature or maturity. Pod width and seed length were shown to be accurate indices of maturity. Total solids appeared to be a good index of edible maturity. The need for revision of standards to account for various rates of maturity onset was stressed.