Victor H. Ramirez-Builes. Graduate student in the Agronomy and soils department-UPRM Research Leader Eric W. Harmsen, Ph

1. USDA TSTAR Evapotranspiration and crop coefficients for two genotypes of common bean (Phaseolus vulgaris L.) with variable surface resistance under water-limited and non-limited conditions. Victor H. Ramirez-Builes. Graduate student in the Agronomy and soils department-UPRM Research Leader Eric W. Harmsen, Ph.D., P.E Associate Professor – Department of Agricultural and Biosystems Engineering-UPRM Timothy G. Porch, Ph.D. Research Geneticist- USDA/ARS, Tropical Agricultural Research Station, Mayaguez, PR ASA-Meeting Indianapolis, Nov,12-16. 2006

2. Dry beans production and drought problem Over 20 million ha of dry beans produced worldwide (8.5 M ha in LAC, 4 M ha in Africa). (Blair, 2005) Drought stress: 73% of the Latin American and 40-50% of African bean production occurs under water-deficit. (Blair, 2005) Drought is endemic in >1.5 millions ha of dry bean planted each in northeastern Brazil and central and northern highlands of Mexico. Muñoz-Perea et al.2006) Western U.S. is characterized by arid and semiarid conditions with inadequate summer rainfall. (Muñoz-Perea et al.2006)

3. Generalized Penman-Monteith equation (P-M) (Penman, 1953; Monteith, 1965). Food and Agricultural Organizartion (FAO-56) method to compute ET ( ET=ETo x Kc). The P-M equation with variable surfaces resistance (rs) can be used directly to compute ET under variable soil moisture conditions. (Abtew and Obeysekera, 1995; Rana et al. 1997; Kjelgaard and Stocle, 2001; Tolk and Howell, (2001) Ortega-Farias et al. 2004; Ortega-Farias et al. 2006) ¿ Could be a good tool for estimating ET directly for partial or sparse canopies under different soil water conditions..?

4. The surface resistance rs=rL/LAIactive(Szeicz and Long, 1969) The rs parameter model of the P-M is particularly difficult to estimate due the combined influence of: Plant-Soil-Climatic factors. Alves et al. (1998) said that rs is no only a physiological parameter. Some Simplifications and empirical relationships has been used: (Kjelgaard and Stocle, 2001; Ortega-Farias et al. 2004) Other alternative is use single rL and variable LAI: Stainer et al. (1991) recommended using rL value of 162 s.m-1 for sorghum Howell et al. (1994) 134 s.m-1wheat, 280 s.m-1 sorghum and 252 s.m-1for corn Monteith (1981) 100 s.m-1 for most arable crops.

5. Objectives • Estimate the crop evapotranspiration (ETc) for two common beans genotypes (SER-16 and Morales) under drought and no-drought stress conditions with variable surfaces resistance. ii) Estimate the crop coefficients (Kc, Ks) for two common beans genotypes (SER-16 and Morales) under drought and no-drought stress conditions. iii) Evaluate the behavior of the Penman-Monteith with variable rs to estimate ET.

6. ET Works in Puerto Rico Source: Harmsen, (2003) “Fifty years of crop evapotranspiration studies in Puerto Rico”. Journal of soil and water conservation

7. Methods Location • Agricultural Experimental Station of Fortuna • 18º01’N and 66º22’W • 21-m above mean sea level. • Semi-arid climatic zone, (Goyal and Gonzalez, 1989) Average annual rainfall is 33 inches [838 mm] January……. 0.78 in (19.8 mm) February…... 0.72 in (18.3 mm) March …… 0.86 in (21.8 mm) (USDA, 1979).

8. Methods (Cont.) Location…..

9. Methods (Cont.) Experimental Design

10. ETc ET0 Prevailing wind direction

11. Methods (Cont.) Fetch requirement thickness of the internal boundary layer (d in m ) and roughness parameter (Zo in m) (Rosenberg et al. 1983; Monteith and Unsworth, (1990); Alves et al. (1998) )

12. Methods (Cont.) Drougth Stress Application Depth FC WP D. S.L 0-20 cm 0.38 0.18 0.23 20-40 cm 0.31 0.20 0.23 0.40 cm3cm-3 cm3cm-3 0.35 0.30 0.25 0.20 0.15 F.C W.P TAW Drought Stress Limit

13. Drought stress signs Өv = 0.21 cm3.cm-3

14. Methods (Cont.)

15. Methods (Cont.) Generalized Penman-Monteith (Allen at al.1998, Kjelgaard and Stockle, 2001),

16. Methods (Cont.) Soil heat flux

17. Methods (Cont.) Aerodynamic resistance Zm: Height of wind measurement (m) Zh: Height of humidity measurement (m) d: Zero displacement height (m) Zom: Roughness length (m) =0.123h governing momentum transfer Zoh: Roughness length (m) = 0.1Zom governing the transfer heat K: von Karman’s contant uz: Wind speed.

18. Methods (cont.) The surfaces resistance

19. Leaf area measurement

20. Methods (Cont.) The Bowen-ratio method (Payero et al. 2003)

21. Methods (Cont.) Crop Coefficients (Kc)….. Kc = ETc/ ETo 1. Water balance method ETc = P + I – RO – DP + [Si-1 – Si]

22. Methods (Cont.) Transverse sight of the Lysimeter

23. Methods (Cont.) Crop Coefficients (Kc) Standarized by ASCE (Walter et al. 2002) Kc = ETc / ETo

24. Methods (Cont.) ETc under soil water stress conditions ETc adj = Ks.Kc ETo TAW : is total available water [mm] Dr: is a root zone depletion [mm] RAW: is the readily available soil water in the root zone p: is the fraction of TAW that the crop can extract from the root zone without suffering water stress. Allen et al. (1999)

25. Methods (Cont.) The soil water stress coefficient (Ks)……. θFC: is the water content at field capacity [m3.m-3], θWP: is the water content at wilting point [m3.m-3], Zt: is the rooting depth [m] p = 0.45+0.004(5-ETc) Allen et al. (1999)

26. Results LAI distribution

27. Results (cont.) rs distribution

28. Results KC Kcmid=0.87 Kcend=0.5 Kcin=0.23

29. Results (Cont.) KC Kcmid=0.85 Kcend=0.60 Kcin=0.20

30. Results (cont.) ETc

31. Results (Cont.) KC Kcmid=0.92 Kcend=0.60 Kcin=0.24

32. Results (Cont.) KC Kcmid=0.85 Kcend=0.60 Kcin=0.24

33. Results (cont.) ETc

34. Results (cont.) Kc. Statistical Results a b= ratio between the Kc measured in the drainage lysimeter and Kc measured using the Penman-Monteith equation. b SEE = standard error of estimate b c T= true hypothesis (b=1), F false hypotesis (b≠1)

35. Results (cont.) Daily ET. Statistical Results a b= ratio between the ET measured using the Penman-Monteith equation (variable rs) and Bowen ratio. b SEE = standard error of estimate b c T= true hypothesis (b=1), F false hypotesis (b≠1)

36. Results (cont.) Hourly ET.

37. Results (cont.) Hourly ET.

38. Results (Cont.) Ks

39. Results (Cont.) Ks

40. Conclusions The ET with variable rs is a successful method to estimate ET in common beans with water limited and no-limited conditions. The low ET rates can be associate with the irrigation type and low LAI in the SER-16 genotype case. The moderate drought stress since reproductive to maturity reduce the yield in both common beans dismiss the ET more in Morales than in SER-16. The Kc for Morales was more longer than for SER-16, specialty for differences in LAI.

41. Acknowledgment • USDA-TSTAR, NASA-EPSCoR and NOAA-CREST • for the economic support. • Dr. Michael Dukes, University of Florida. • University of Puerto Rico- Research Station. • Fortuna- Experiment station Team. • Ruth Amanda Acero, Graduate student.