Effect of a dynamic climate control on energy saving, yield and shelf life of spring production of bell peppers (Capsicum annuum L.)

摘要

Bell pepper 'Fiesta' (Capsicum annuum L.) was grown in a novel dynamic climate concept called 'Intelli-Grow' together with a number of potted plants aiming to save energy under low light conditions and to optimise photosynthesis (and thereby carbongain that can be used for growth) under high light conditions. The dynamic climates utilize the plants ability to increase the photosynthesis and productivity under adequate light conditions by allowing temperature to increase while supplying the plantswith extra CO_2. Energy is saved by allowing the temperature to decrease to lower levels than usual at low light conditions when the temperature response curve of photosynthesis is very flat. Both temperature and CO_2 is determined by the light level (light dependent temperature and CO_2 increase in the climate computer). It is possible to reduce the energy use needed for bell pepper growing by up to 21 percent in this experiment depending on climate control strategy. Temperatures below 17 deg C resultsin reduced fruit quality in terms of size and quality and increased risk of grey mould and also a delay in the harvest start. On the other hand the total number of fruits was not affected in a similar way. The standard climate 21/19 dayight with 600 ppm CO_2 in light and the dynamic climate using 80 percent photosynthesis and a minimum temperature set point of 17 deg C, especially in combination with short peaks of higher night temperature gave the same or better harvest and approximately the same quality. The fruits in the warmest climate, however, had a slightly lower dry matter- percent .There were limited damages (spots, sun burns) due to the relatively higher temperatures during the day even thought the air temperature was allowed to rise to 30deg C during the days. The increased CO_2 level might have alleviated some of the potential damages due to high fruit temperatures. The major problem was remains of the flowers on the fruits, which created an entry point for grey mould. The post harvestquality of the fruits was therefore poorer in the dynamic climates due to infection with Botrytis primarily through the flowers and secondarily through the fruit stem. A modified energy saving strategy therefore requires a change in harvest procedure toremove flower remains.