Yield response to water. The impact of “future” climate projections (2050) and “extreme weather” (2050+1) on potential yield, also considering the relative effect of selected adaptation strategies (planting dates, variety selection and deficit irrigation strategies), is summarized in the following tables and graphs. In brief, the following observations are reported: ‐ maximum yield is expected to reduce under “future” scenario (2050) with respect to current conditions (2000), on average from 5.9 to 5.5 t ha‐1 (about ‐6.5%), depending on irrigation strategies (tab. 23 and fig.14) and planting dates (tab. 24 and fig. 14) as a consequence of the expected shortening of the crop growing cycle; ‐ on the contrary, if the expected fertilizing effect due to increase in atmospheric CO2 concentration will occur, yield is projected to increase in quite all conditions (2050 wp_adj), up to an average of 6.6 t ha‐1 (+12.2%), and thus to overcome the effect of the shortening of the crop cycle (fig. 14 and tab. 23‐24); ‐ on the other side, if a late maturing variety (2050 late_var) is selected, yield is projected to increase up to an average of 6.1 t ha‐1 (+5%), especially under fully irrigation (fig. 14 and tab. 23‐24); ‐ if “extreme weather” conditions (2050+1) are considered, the average expected yield reduction (down to 5.3 t ha‐1, ‐9.2%) is greater than in 2050 scenario, but also in this case it could be completely recovered because of the CO2 fertilizing effect or the late‐variety selection, respectively to 6.4 t ha‐1 (+5%) and 6 t ha‐1 (+2.8%); ‐ with respect to irrigation strategies, there is a clear reduction in potential yield under increasing water stress conditions (fig. 14), but still under “severe” water stress (thus only supported by supplemental irrigations) values up to 3‐4 t ha‐1 are expected, while under rainfed conditions, an average yield of 1.5 t ha‐1 is still predicted in all climate conditions; ‐ yield is observed always to increase (in absolute terms) for late (February) planting date with respect to earlier (October) ones (fig. 14), but a corresponding increase in crop water requirements is clearly projected (as it has been highlighted in the previous paragraph). Tab. 23– Effect of irrigation strategies, variety selection and atmospheric CO2 increase on the potential yield of wheat in Jordan river basin (Jordan) under “present”, “future” and “extreme weather” climate conditions. Irrigation strategy Yield 2000 (*) Yield 2050 (*) Yield 2050 wp_adj (**) Yield 2050 late_var (...
Yield response to water. The impact of climate change on potential yield, also considering the relative effect of selected adaptation strategies (planting dates, variety selection and deficit irrigation strategies), is summarized in the following tables and graphs. In brief, the following observations are reported: ‐ maximum yield is projected to reduce under “future” scenario (2050) with respect to current conditions (2000), on average from 32.8 to 29.4 t ha‐1 (about ‐10.3%), depending on irrigation strategies (tab. 35 and fig. 26) and planting dates (tab. 36 and fig. 26) as a consequence of the expected shortening of the crop growing cycle; ‐ on the contrary, if the expected fertilizing effect due to an increase in atmospheric CO2 concentration will occur, yield (2050 wp_adj) is projected to increase in quite all conditions (with an average of 35.3 t ha‐1, +7.6%), and thus to overcome the effect of the shortening of the crop cycle (fig. 26 and tab.35‐36); ‐ on the other side, if a late maturing variety (2050 late_var) is selected, yield is projected to remain stable or slightly increase (with an average of 32.6 t ha‐1, ‐0.7%), depending on irrigation strategy and planting dates (fig. 26 and tab.35‐36); ‐ there is a clear reduction in potential yield under increasing water stress conditions (fig.26), and under “severe” water stress (thus only supported by supplemental irrigations) values of 12‐20 t ha‐1 are predicted; in the case of rainfed conditions, very low yield (around 6 t ha‐1) is expected in all conditions; ‐ yield is observed always to increase (in absolute terms) for late (February) planting date with respect to earlier (October) ones (fig.26), because of the corresponding increase in total maximum crop evapotranspiration. Tab. 35 – Effect of irrigation strategies, variety selection and atmospheric CO2 increase on the potential yield of potato in Jordan river basin (Jordan) under “present” and “future” climate conditions. Irrigation strategy Yield 2000 (*) Yield 2050 (*) Yield 2050 wp_adj (**) Yield 2050 late_var (*) (t/ha) (t/ha) (variation vs 2000) (t/ha) (variation vs 2000) (t/ha) (variation vs 2000) full 32.8 29.4 ‐10.3% 35.3 7.6% 32.6 ‐0.7% mild1 29.9 27.0 ‐9.7% 32.4 8.4% 29.7 ‐0.6% mild2 26.0 23.8 ‐8.5% 28.6 9.8% 26.0 0.0% medium 24.5 22.3 ‐8.9% 26.8 9.4% 24.5 ‐0.1% severe1 19.0 17.7 ‐7.1% 21.2 11.5% 19.1 0.4% severe2 13.2 12.5 ‐5.3% 15.0 13.6% 13.4 1.1% rainfed 5.7 5.8 0.9% 6.9 21.1% 5.9 2.9% (*) assuming wp (2000) = 5 (kg/m3) (**) assuming wp (2050)= wp(2000)*1....
Yield response to water. The impact of climate change on potential yield, considering the relative effect of selected adaptation strategies (deficit irrigation strategies), as estimated by the two different yield response models of Xxx et al. (1988) and Xxxxxxx et al. (2003) (presented in chapter 2.1.3) are summarized in the following tables and graphs. According to the results of the first model (Xxx et al., 1988) (tab. 42‐43 and fig.29): ‐ yield is projected to increase under both “future” (2050) and “extreme weather” (2050+1) scenarios with respect to current conditions (2000), on average respectively from 13.9 to 14.6 (about +5%) and to 14.7 t ha‐1 (+5.9%), depending on irrigation strategies and Kc model considered, as a consequence of the expected increase of ETc; ‐ a clear linear reduction in potential yield under increasing water stress conditions is observed (fig.29); ‐ under “severe” water stress (thus only supported by supplemental irrigations) values of 4‐7 t ha‐1 are still predicted; ‐ in the case of rainfed conditions, very low yield (around 1 t ha‐1) is predicted. According to the results of the alternative model (Xxxxxxx et al., 2003) (tab. 44‐45 and fig.30): ‐ yield is projected to remain relatively stable or slightly decrease under both “future” (2050) and “extreme weather” (2050+1) scenarios with respect to current conditions (2000), on average from 11.5 to 11.3 (about ‐1.4%), depending on irrigation strategies and Kc model considered: ‐ as a consequence of the specific shape of the yield response function curve, a relative stability of potential yield is predicted going from full irrigated to medium stressed conditions, and then reducing under severe stress (only supported by supplemental irrigations) where values of 4‐9 t ha‐1 are still predicted; ‐ in the case of rainfed conditions, no yield is predicted. Tab. 42 – Effect of irrigation strategies on the potential yield of olive in Jordan river basin (Jordan) under “present”, “future” and “extreme weather” climate conditions. Irrigation strategy Yield 2000 (*) Yield 2050 (*) Yield 2050 +1 (t/ha) (t/ha) (variation vs 2000) (t/ha) (variation vs 2000) full 13.9 14.6 5.0% 14.7 5.9% mild1 13.0 13.7 5.2% 13.7 5.3% mild2 10.2 10.6 4.2% 10.6 3.9% medium 9.4 10.1 7.6% 10.1 7.1% severe1 7.1 7.5 5.6% 7.3 3.1% severe2 4.1 4.4 6.4% 4.2 3.2% rainfed 1.0 1.0 8.7% 0.9 ‐3.6% (*) assuming wp (2000) = 1.5 (kg/m3) Tab. 43 – Effect of different Kc models on the potential yield of olive in Jordan river basin (Jordan) under “present”...
