Study the response of three date palm cultivars of Kabkab, Zahidi and Shahabi to deficit irrigation in Bushehr, Iran

There are more than 5.5 million date palms in Bushehr province in southern Iran. Repeated droughts and lack of irrigation water in recent years are being the most important factors for yield reduction and low quality of date fruits. Proper utilization of water supplies in order to increase water use efficiency and also, identification of more tolerant plants are so sensed according to recent drought crisis in the region. Although, date palm can suffer water shortage for a long time but higher water levels and annual soil temperature between 17 to 45 centigrade degrees would make the highest production. Therefore, a study was conducted in Bushehr Agricultural Research Center to determine the responses of three date palm cultivars of Kabkab, Zahidi and Shahabi to deficit irrigation. This experiment was carried out on randomized complete block design with three replications during 2004 to 2007. The irrigation treatments of this study were water depth in four levels of 35, 50 and 65 percent of irrigation water, which shows the cumulative evaporation of class A pan. Irrigation water was offered to plants under pressured system. Tree responses were evaluated in each year for the following properties: fruits and seeds weight, length and diameter, pulp to seed ratio, TSS, pH and yield. Results showed that cultivar effect was significant in all date palm responses (p>0.01) which can prove different inherent qualitative and quantitative characteristics in date palm cultivars. Zahidi cultivar proved to have higher water use efficiency in water stress conditions during drought periods. Irrigation treatments affected only the yield responses. Although, 65 percent of irrigation water showed to have higher production abut it was classified in the same statistical class with 50 percent of irrigation water. This means that in the situation of water shortage, 50 percent of irrigation water would be the choice. Also, mean water usage during three years of the experiment were 5497, 7758 and 9822 m3 ha-1 per year in the irrigation treatments with 0.544, 0.481 and 0.409 kg m-3 water use efficiency respectively. The sequence of water stress toleration in three date palms was Zahidi > Shahabi > Kabkab.