Deficit Irrigation to Control Vegetative Growth in Apple and Monitoring Fruit Growth to Schedule Irrigation

Abstract

Additional index words. Malus domestica, croploadAbstract. A standard fruit growth curve, used commercially as an aid to hand thinning, was compared to periodic volume measurements of apple fruit (Malus domestica Borkh. 'Delicious') subjected to early season regulated deficit irrigation (RDI) to determine when to end RDI, which is used to control vegetative growth and save water. RDI suppressed stem water potential, stomatal conductance, and fruit growth rate compared to the trickleand furrow-irrigated controls, which wetted about one-half and the entire soil volume, respectively. Full irrigation was restored to RDI trees by trickle and microsprinklers, which wetted about one-half and the entire soil volume, respectively, after terminal buds set. Stem water potential, stomatal conductance, and fruit growth rate of RDI trees increased to that of the controls, except for RDI/trickle trees, which had 80% the stomatal conductance of the other treatments. Fruit weight at harvest was affected by an interaction of irrigation treatment and cropload. RDI trees had similar or less vegetative growth and similar or higher yield efficiency than the controls. We recommend ending RDI before fruit growth declines below the standard curve.

Morpho-physiological and Yield Responses of Sweet Potato (Ipomoea batatas (L.) Lam.) Genotypes to Frequency of Irrigation under Greenhouse Condition

“…Moreover, Laurie and Magoro [25] also reported that reduction in vine length of sweet potato has been positively correlated to the decline in irrigation rates from 100% full irrigation to 30% irrigation. Similar to the present study, Ebel et al [26] found that an extended irrigation interval led to decrease in percentage of vine length in sweet potato. Branch number was also found to be significantly reduced when extended irrigation interval was considered.…”

Methods and technologies to improve efficiency of water use

“…These management strategies are taking advantage of physiological responses of certain crops to drought stresses that result in a reduction in vegetative production in favor of fruit yield. Research has shown beneficial responses in Australia on peaches [ Chalmers et al , 1981] and pears [ Mitchell et al , 1984]; and in Washington on apples [ Proebsting et al , 1977; Middleton et al , 1981; Peretz et al , 1984; Evans et al , 1993, Ebel et al , 1995; Drake and Evans , 1997], citrus [ Goldhamer and Salinas , 2000], grapes [ Evans et al , 1990; Dry and Loveys , 1998; McCarthy et al , 2000], and other crops. These results have shown that carefully managing the severity and duration of a uniform, constant level of water stress on vigorous perennial crops can be advantageous to crop quality, depending somewhat on rootstocks and varieties.…”

Fruit Growth Measurement and Analysis

“…Fruit growth measurement and analysis is therefore an important tool in assessing the impact ofRDI Mitchell et al 1989;Durand 1990;Pola et al 1991;Behboudian et al 1994;Mills et al 1996). In addition to using fruit growth data to assess the impact of RDI, researchers have also monitored fruit growth as a tool to schedule irrigation in fruit trees (Ebel et al 1995).…”