Environmental factors affecting the cracking of greenhouse-grown bell pepper fruit

The cracking of bell pepper fruit is one of the main physiological disorder s that reduce marketable yield. Understanding the environmental and endogen ous factors that influence this disorder may help to reduce its severity. P lants grown in three greenhouses were subjected to differing potential tran spiration (Tp) at night, with identical daytime Tp, Measurements included c limatic variables in the greenhouses, soil water content, sap flow, transpi ration, leaf temperature, surface and internal fruit temperatures, fruit an d stem diameters, stomatal conductance, and leaf area. The results show tha t at night pepper plants transpired at a rate proportional to the vapour pr essure difference (leaves to air; VDPla) in the respective greenhouses. The percentage of cracked fruits was highest in the greenhouse with the lowest night vapour pressure deficit (VPD) and lowest in the greenhouse with the highest VPD. Both increased direct radiation reaching the fruit surface and decreased soil water content reduced the growth rate of the fruit. Direct radiation and the temperature of the fruit inner space were well correlated with diurnal expansion and shrinkage of the fruit. The fruits with the hig her expansion-shrinkage amplitude had more severe cracking symptoms. Decrea sed soil water potential counteracted the negative effect of direct radiati on. These results indicate that the water status of the fruit is a key fact or in determining the severity of fruit cracking. The implications of these results for greenhouse management in pepper production are discussed.