APPLE LEAF GAS EXCHANGE MEASUREMENTS IN 'BROOKFIELD GALA' TREES UNDER THREE WATER AND NUTRIENT MANAGEMENT STRATEGIES

In this study, the use of water and nutrient management strategies through single (fertigation) and more frequent (pulsating) daily drip systems was compared to the conventional micro jet irrigation system on two rootstocks (‘M793’ and ‘M7’) together with hand application of nutrients in the Western Cape Province, South Africa. During the 2004/2005 and 2005/2006 seasons, seasonal gas exchange measurements were made on 2-3 year old ‘Brookfield Gala’ apple trees under each system, to determine photosynthetic rate, stomatal conductance, transpiration rate, and instantaneous leaf water use efficiency. Pre-dawn and midday leaf water potential measurements were made throughout the season using a pressure chamber. Results indicated higher photosynthetic rates, and higher leaf water use efficiency during the warm summer months in the conventional drip and pulsating drip compared to micro jet irrigation system.