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Crop yield response to water - Cra

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minimal4season 1 (l h -1 )4eason 1 (l h -1 )4Figure 7 Reduction in irrigation rate post-veraison in season 1 reduced <strong>yield</strong> and bunch number ofShiraz in season 2 irrespective of pruning system. Yield and bunch number are expressed as per2metre of canopy. Source: Petrie et al. (2004).0spur mechanical minimal0 2 4spur mechanical minimalspur mechanical minimalPost-veraison irrigation in season 1 (l h -1 )8886120664irrigation: P < 0.058044pruning: n.s.irrigation: P < 0.05irrigation: P < 0.052interaction: n.s.pruning: n.s.pruning: n.s.4022interaction: n.s.interaction: n.s.00 2 40Post-veraison irrigation 0 in season 1 (l h -1 )00 2 0 4 2 40 2 4120Post-veraison irrigation in season Post-veraison 1 (l h -1 ) irrigation in season 1 (l hPost-veraison -1 )irrigation in season 1 (l h -1 )Brunch number in season 2 (m -1 ) Yield in season 2 (kg m -1 )Brunch number in season 2 (m -1 ) Yield in season 2 (kg m -1 )irrigation: 120 P < 0.0580pruning: n.s.interaction: n.s.80 40Brunch number in season 2 (m -1 ) Yield in season 2 (kg m -1 )12080Brunch number in season 2 (m -1 ) Yield in season 2 (kg m -1 )86irrigation: P < 0.05pruning: P < 0.01interaction: n.s.irrigation: P < 0.05pruning: P < 0.01interaction: n.s.spur mechanical minimalirrigation: P < 0.05pruning: P < 0.01interaction: n.s.40Figure 80400 2 4Shoot development recorded on mid-Oc<strong>to</strong>ber (pho<strong>to</strong>graphs) and <strong>yield</strong> components at harvest0 (numbers)Post-veraisonin Merlotirrigation season 1 (l h -1 )0 vines pruned at monthly intervals between mid-July <strong>to</strong> mid-Oc<strong>to</strong>ber.0Source: Friend and 2 Trought 0 (2007) for 4 experiments 2 in Marlborough 4 (41 o S, 174 o E), New Zealand.irrigation: P < 0.05Post-veraison irrigation in season Post-veraison 1 (l h -1 ) irrigation in season 1 (l h -1 )pruning: P < 0.01JulyAugust September Oc<strong>to</strong>berinteraction: n.s.Bunches per vine:Berries per bunch:Berry size (g):52860.4570820.5765680.8862491.16irrigation: P < 0.05pruning: n.s.interaction: n.s.irrigation: P < 0.05pruning: P < 0.01interaction: n.s.of <strong>water</strong> supply <strong>to</strong> ensure berry growth and the requirements of berry composition, which maybenefit from controlled <strong>water</strong> deficit.Fewer studies characterized the long-term effect of <strong>water</strong> deficit on grapevine <strong>yield</strong>. For Riesling ona steep slope vineyard in Germany, the combination of in-season and across-season temporary <strong>water</strong>deficits reduced long-term production from an average 7.6 <strong>to</strong>nne/ha in vines with small amounts ofsupplementary irrigation (29 litre/m 2 per season) <strong>to</strong> 5.0 <strong>to</strong>nne/ha for rainfed vines (Table 4).Availability of <strong>water</strong> after harvest has at least two effects. First, it may influence canopy activity,build up of reserves and hence the performance of the crop in the following growing cycle.Second, irrigation between harvest and leaf fall may alter phenology under some conditions; forinstance reduced irrigation after harvest may advance budburst in the following season (Williamset al., 1991), potentially increasing frost risk in some environments.grapevine 469

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