The second of a four-year study to investigate the effects of irrigation frequency on Thompson Seedless productivity was concluded in 1999. The irrigation frequency treatments included: a.) the application of water whenever the vines in a weighing lysimeter used 2mm (2.11 gallons) of water, b.) the application of water once a day (the amount being equivalent to the day’s use of water by the lysimeter), c.) the application of water every three days (the amount being equivalent to three days use of water by the lysimeter) and d.) the application of water once a week (the amount being equal to a week’s use of water by the lysimeter). In addition to the frequency treatments, water was applied in three different amounts: 60, 80 and 100%of lysimeter vine water use. Lastly, three different trellis treatments were included. The trellis treatments consisted of a single wire, a 0.6 m (2 ft) crossarm and a 1.2 m (4 ft) crossarm. Vine density in the vineyard was 1318 vines per hectare (533 vines per acre). Irrigation of the vines in the lysimeter and the rest of the vineyard commenced on April 19th. Vine water use between budbreak and bloom was 750 liters (200 gallons) per vine and between budbreak and harvest was 5800 liters (1534 gallons). The water use between budbreak and harvest was equivalent to 762 mm (30 inches). The amount of water applied to the 60, 80 and 100%of ET irrigation amounts was 58, 76 and 100%of actual vine water use (measured with the weighing lysimeter). Irrigation amounts had the predominant effect on midday leaf water potential. Averaged across the frequency and trellis treatments, the 60, 80 and 100%irrigation treatments midday leaf water potential values were -1.25, -1.08 and -0.91 MPa, respectively. There was a significant effect of irrigation frequency on berry weight. Irrigation amount and trellis type had significant effects on berry weight and soluble solids. However, there were no significant interactions among the treatments with regard to berry weight or soluble solids. The 60%irrigation amount had the smallest berries and the highest soluble solids. The single wire trellis had the smallest berries and thel.2 m crossarm had the highest soluble solids. There were no significant effects of the treatments on final yield. It is anticipated that two more years of study are needed to accurately assess the effect of irrigation frequency on Thompson Seedless productivity at this location.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF1999-10-18 10:25:502017-10-18 10:26:34Effect of Irrigation Frequency on Productivity of Thompson Seedless Grapevines