干旱区生态环境知识资源中心

A project to improve the crop production in arid area is underway in Guerrero Negro, Baja California, Mexico as a joint enterprise of Japanese and Mexican Government. The objective of this project is to establish the production system of vegetables and fruits by drip irrigation in the desert area. The mineral composition of xylem sap and bleeding rate in pepper and melon at the harvest stage were examined to obtain basic data for the study of salinity problems. The mineral composition of xylem sap in the field-grown pepper differed between daytime and night time. Bleeding rate in pepper also showed a diurnal change with the maximum value at around noon. On the other hand, in field-grown melon, neither bleeding rate nor mineral composition of xylem sap showed such diurnal changes. The mineral composition of xylem sap was analyzed in relation to the bleeding rate. The results showed that the concentration of Na+ was low in the daytime when the bleeding rate was high and high in the night time when the bleeding rate was low in both field-grown pepper and pot-grown melon. Then mineral composition of xylem sap was also examined in the plants grown on different soils. These information on mineral composition in xylem sap and bleeding rate as well as soil chemical coniditions may be useful for improving the salinity tolerance of crops.