Crop yield response to water - Cra
Crop yield response to water - Cra Crop yield response to water - Cra
ox 5 Computing olive tree transpiration independently of the other ET components.After E is calculated following the methods described above in Box 4, tree transpiration,Tr (mm), may be calculated as the product of the intercepted radiation by the treeand two factors (F 1 and F 2 ) which are related to canopy conductance. These factorswere calibrated and tested for olive in a Mediterranean environment (Testi et al., 2006and Orgaz et al., 2006). The method has also been tested in an arid environment inArgentina and in other Mediterranean-type environments.Tr = ET o K c,TrWhere, K c,Tr is a transpiration coefficient calculated as:K c,Tr = (Q d F 1 ) F 2Where, Q d is the intercepted radiation by the tree (fraction), calculated as:Q d = 1 – e - K ext V uWhere,K ext = 0.52 + 0.00079 d p – 0.76 e – 1.25 DAF,DAF = 2 – 0.53 (Vu – 0.5); (Note: DAF must be < 2),V u = V o (d p /10 000), and,V o = 1/6 π D 2 HSymbols:Tr : Tree Transpiration (mm)ET o : Reference evapotranspiration(mm)K c,Tr : Transpiration coefficientF 1 : Depends on tree density; F 1 = 0.72for tree densities of < 250 tree/haand F 1 = 0.66 for tree densities >250 tree/ha.F 2 : Monthly coefficient from TablebelowK ext : Radiation extinction coefficientd p : Tree density (tree/ha)DAF: Leaf area densityV u : Canopy volume per unit groundsurface (m 3 /m 2 )V o : Canopy volume (m 3 /tree)D : Canopy average diameter (m)H : Canopy height (m)e: Exponent (2.718)Yield Response to Water of Fruit Trees and Vines 263
ox 5 (CONTINUED)F 2 VALUES (Northern Hemisphere)Month F 2January 0.70February 0.75March 0.80April 0.90May 1.05June 1.25July 1.25August 1.20September 1.10October 1.20November 1.10December 0.70B CALCULATING EVAPOTRANSPIRATION with the K c MethodIf it is not possible to calculate Tr separately, what is needed is an overall crop coefficient (K c )that embodies all the components of ET c . The FAO I&D No. 56 provides the K c values for treecrops and vines, derived from the original values published in FAO I&D No. 24. The differentcrop sections in this publication provide sets of K c values for the different tree crops and vines,which are an update of those published earlier in FAO I&D No. 56.As shown in Figure 10, the crop coefficient (K c ) for deciduous orchards on bare soil, increasessharply in spring in response to bud break and leafout until it reaches a maximum in earlysummer. The peak K c value is maintained until harvest, after which it declines temporarily forsome tree crops. In others, the maximum K c stays more or less the same until the beginningof senescence, when it starts to decline until leaf fall is complete. For evergreen trees, theremay be variations in K c within the season, caused by changes in leaf area, and by responseseither to environmental changes or to internal tree signals. It should be emphasized that thestandard K c values include an average E component but do not include the Tr cc from covercrops, unless specifically stated.Determining the ET of partial tree canopiesWhen information exists to compute ET c as the sum of its components (Equation 4), the sameprocedure may be applied to non-mature, developing orchards where trees have not yetachieved their mature size. It suffices to measure the canopy parameters that characterizethe radiation intercepted by the young trees and to compute the Tr, using a method suchas the one in Box 5. The standard K c procedure described above specifically applies to264crop yield response to water
- Page 228 and 229: Figure 1 Alfalfa harvested area (SA
- Page 231 and 232: Water use & ProductivityAs a perenn
- Page 233 and 234: SalinityAlfalfa is tolerant to rela
- Page 237 and 238: Lead AuthorAsha Karunaratne(formerl
- Page 239 and 240: Generally, the growing season begin
- Page 241 and 242: FAO. 2011. FAOSTAT online database,
- Page 244 and 245: *Flower and grain colour presented
- Page 246 and 247: Figure 1 World quinoa harvested are
- Page 248 and 249: with typical values around 10.5 g/m
- Page 250: ReferencesAlvarez-Jubete, L., Arend
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- Page 256 and 257: soils (EARO, 2002). Tef has some to
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- Page 261 and 262: Lead AuthorsElias Fereres(Universit
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- Page 268 and 269: figure 6 The water balance of an or
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- Page 272: Orchard transpirationTree Tr is det
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- Page 280 and 281: FIGURE 10 Crop coefficient (K c ) c
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- Page 288 and 289: ox 9 Examples of soil water monitor
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- Page 294 and 295: The water budget methodWith this me
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- Page 302 and 303: The crop, where price can vary more
- Page 304: Modify horticultural practicesPruni
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- Page 309 and 310: season. Thus the risks of salinity
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- Page 315 and 316: Figure 1 Production trends for oliv
- Page 317 and 318: Figure 2Occurrence and duration of
- Page 320 and 321: The use of displacement sensors to
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ox 5 Computing olive tree transpiration independently of the other ET components.After E is calculated following the methods described above in Box 4, tree transpiration,Tr (mm), may be calculated as the product of the intercepted radiation by the treeand two fac<strong>to</strong>rs (F 1 and F 2 ) which are related <strong>to</strong> canopy conductance. These fac<strong>to</strong>rswere calibrated and tested for olive in a Mediterranean environment (Testi et al., 2006and Orgaz et al., 2006). The method has also been tested in an arid environment inArgentina and in other Mediterranean-type environments.Tr = ET o K c,TrWhere, K c,Tr is a transpiration coefficient calculated as:K c,Tr = (Q d F 1 ) F 2Where, Q d is the intercepted radiation by the tree (fraction), calculated as:Q d = 1 – e - K ext V uWhere,K ext = 0.52 + 0.00079 d p – 0.76 e – 1.25 DAF,DAF = 2 – 0.53 (Vu – 0.5); (Note: DAF must be < 2),V u = V o (d p /10 000), and,V o = 1/6 π D 2 HSymbols:Tr : Tree Transpiration (mm)ET o : Reference evapotranspiration(mm)K c,Tr : Transpiration coefficientF 1 : Depends on tree density; F 1 = 0.72for tree densities of < 250 tree/haand F 1 = 0.66 for tree densities >250 tree/ha.F 2 : Monthly coefficient from TablebelowK ext : Radiation extinction coefficientd p : Tree density (tree/ha)DAF: Leaf area densityV u : Canopy volume per unit groundsurface (m 3 /m 2 )V o : Canopy volume (m 3 /tree)D : Canopy average diameter (m)H : Canopy height (m)e: Exponent (2.718)Yield Response <strong>to</strong> Water of Fruit Trees and Vines 263
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