Articles
Quantification of water use and water productivity of irrigated apple orchards under draped nets in a Mediterranean-type climate
Article number
1468_19
Pages
141 – 150
Language
English
Abstract
Irrigated apple production in Mediterranean-type climates is increasingly limited by water scarcity.
Significant water savings and improvements in crop water productivity (WP) may be achieved under draped net.
This study was conducted in a ‘Golden Delicious Reinders’ orchard in the Koue Bokkeveld (KBV) region of South Africa and repeated in a ‘Golden Delicious’ orchard in the Villiersdorp area.
Daily and seasonal microclimate, midday stem water potential (Ψstem), transpiration (T), basal crop coefficient (Kcb) and T-based WP under 24% black draped net (four rows) was compared to adjacent open (control) rows of the same orchard block.
At both sites, netting reduced solar radiation by 21-37%, with a similar reduction in reference evapotranspiration (ETo). Reduced wind speed and increased relative humidity played a relatively small role in reducing ETo. Netting increased Ψstem, more so when control Ψstem was lower than -1.5 MPa.
While the net was installed, T was 8.5% (KBV) and 8.3% (Villiersdorp) lower under the net.
Seasonal T at KBV was 6170 m3 ha‑1 (control) compared to 5970 m3 ha‑1 under the net.
At Villiersdorp, seasonal T was 8120 m3 ha‑1 (control) compared to 6930 m3 ha‑1 (net), a 15% reduction in water use.
The net reduced mid-season Kcb (during installation) from 0.50 to 0.45 (KBV), and from 0.79 to 0.70 (Villiersdorp). The T-based WP was 25.5 kg m‑3 under the net and 23.2 kg m‑3 in the control in KBV, and 16.8 and 12.6 kg m‑3, respectively in Villiersdorp.
The findings demonstrate that water saving benefits are possible in apple orchards under draped net.
Growers should take care not to over-irrigate under the net.
Significant water savings and improvements in crop water productivity (WP) may be achieved under draped net.
This study was conducted in a ‘Golden Delicious Reinders’ orchard in the Koue Bokkeveld (KBV) region of South Africa and repeated in a ‘Golden Delicious’ orchard in the Villiersdorp area.
Daily and seasonal microclimate, midday stem water potential (Ψstem), transpiration (T), basal crop coefficient (Kcb) and T-based WP under 24% black draped net (four rows) was compared to adjacent open (control) rows of the same orchard block.
At both sites, netting reduced solar radiation by 21-37%, with a similar reduction in reference evapotranspiration (ETo). Reduced wind speed and increased relative humidity played a relatively small role in reducing ETo. Netting increased Ψstem, more so when control Ψstem was lower than -1.5 MPa.
While the net was installed, T was 8.5% (KBV) and 8.3% (Villiersdorp) lower under the net.
Seasonal T at KBV was 6170 m3 ha‑1 (control) compared to 5970 m3 ha‑1 under the net.
At Villiersdorp, seasonal T was 8120 m3 ha‑1 (control) compared to 6930 m3 ha‑1 (net), a 15% reduction in water use.
The net reduced mid-season Kcb (during installation) from 0.50 to 0.45 (KBV), and from 0.79 to 0.70 (Villiersdorp). The T-based WP was 25.5 kg m‑3 under the net and 23.2 kg m‑3 in the control in KBV, and 16.8 and 12.6 kg m‑3, respectively in Villiersdorp.
The findings demonstrate that water saving benefits are possible in apple orchards under draped net.
Growers should take care not to over-irrigate under the net.
Authors
E.B. Lulane, S.J.E. Midgley, T. Volschenk, S. Dzikiti, E. Lötze
Keywords
crop coefficient, microclimate, protective net, transpiration, water potential
Groups involved
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