|Ramirez, Victor - GRAD STUDENT-UPR-MAYAGUEZ|
|Harmsen, Eric - UPR, MAYAGUEZ, PR|
Submitted to: Sociedad Puertorriquena de Ciencias Agricolas
Publication Type: Abstract Only
Publication Acceptance Date: September 29, 2005
Publication Date: N/A
Technical Abstract: Stomatal resistance (rl), surface resistance (rs) and leaf temperature (TL) are important physiological variables for the understanding of the interaction between the soil, plant, and atmosphere. These variables are used to study the response of plants to abiotic stress conditions, such as drought and high temperature, in addition to micrometeorological variables such as evapotranspiration (ET). The goal of this research was to measure the rl, rs and TL of four genotypes of common bean (Phaseolus vulgaris L) under drought and non-drought conditions in a greenhouse environment. Three drought-tolerant genotypes were studied, BAT-477, SER-16 and SER-21, and one drought susceptible genotype, Morales. Three water regimes were used: full water supply (FWS) using 80% of the available water (AW) during the complete growing season; Stress 1 (S1) with 50% of the AW before flowering and 60% of the AW after flowering; and Stress 2 (S2) with 20% of the AW before flowering and 40% of the AW after flowering. Measurements were taken throughout the day at different stages of growth. The preliminary results show that there were differences in the rl, rs and TL between genotypes and between water levels, especially during the afternoon. The major differences were found between treatments S1 and S2 during reproductive development. SER-21 and Morales had the highest rs values, 332.1 ms-1 and 233.5 ms-1 respectively, under the S2 treatment, while SER-16 and BAT-477 showed values of 138.6 ms-1 and 140.9 ms-1, respectively, under the same conditions. Values for stomatal resistance showed the same tendency as surface resistance, while there were smaller differences found for leaf temperature. The rs values will be used for ET calculations in future work using micrometeorological methods.