Wednesday, August 1, 2012
Grand Ballroom
Drip irrigation was evaluated as an alternative to conventional seepage irrigation to maximize water and fertilizer use efficiency, while maintaining yield and tuber quality. Potato varieties, ‘Fabula’ and ‘Red LaSoda’ were irrigated using surface drip (SD), sub-surface drip, with tape buried 10.2 cm below soil surface (SSD), or seepage (SP) irrigation. Tubers were harvested 1, 2 and 3 weeks after vine kill. Tuber marketable yield and internal and external quality were determined at harvest. The freshly harvested tubers were stored for 14 days at 10°C and 90-95% relative humidity. Tubers were analyzed every 7 days during storage for bruise susceptibility, firmness, and moisture and vitamin C content. To induce bruising, tubers were dropped individually from 90cm onto a solid surface and held at 20°C for 4 days, before evaluations for internal damage. Similar yields were obtained for SP and SD ‘Fabula’ plants, with an average yield 25% higher than SSD, whereas in Red LaSoda, SP yields were significantly higher than both drip irrigation methods. However, a higher incidence of physiological disorders was also observed in SP tubers for both varieties. Freshly harvested, SP irrigated ‘Fabula’ tubers were most susceptible to bruise injury at all the harvest times, with an average rating of 3.5, compared to 4.8 for the drip methods (rating: 5 = no symptoms of bruising; 1 = extreme bruising). In ‘Red LaSoda’, SP tubers had an average vitamin C content of 36.1mg/100 g during storage, which was 25% and 34% higher than SD and SSD, respectively. Vitamin C was also affected by time of harvest; it increased with tuber harvest maturity in both varieties. No other significant differences in tuber compositional quality were observed among the irrigation methods. The results indicated comparable yields and tuber quality for SP and SD irrigation in ‘Fabula’, whereas there seemed to be no advantage in using the drip methods in ‘Red LaSoda’.