Resumen

BARRIOS-GOMEZ, Edwin Javier; LOPEZ-CASTANEDA, Cándido  y  KOHASHI-SHIBATA, Josué. Water relationships and high temperatures in “Flor de Mayo” type beans. Agron. Costarricense [online]. 2011, vol.35, n.1, pp.131-145. ISSN 0377-9424.

Soil water deficit and high air temperature effects on plant water relations and canopy temperature (CT), and seed yield (SY) and its components in 8 “Flor de Mayo” (FM) bean varieties and a landrace were studied. Three experiments were carried on under field conditions; Montecillo irrigation (MI) with watering from sowing to maturity, Montecillo rain-fed (MRF) with rainfall as the only source of water and Celaya rain-fed (CRF) with rainfall + 2 supplementary waterings at flowering. Rates of 80 kg.ha^-1 Nitrogen and 40 kg.ha^-1 Phosphorous were used. Leaf water (ψ=-0.33 Mpa), osmotic (π=-1.26 Mpa) and turgor (P=0.93 Mpa) potentials at MI were higher than at CRF (ψ=-0.77, π=-1.36 y P=0.59 Mpa) and MRF (ψ=-1.22, π=-1.57 y P=0.35 Mpa); MRF with a greater soil water deficit, showed greater reduction in ψ and π and higher capacity for osmotic adjustment (OA). OA was positive and significantly related to seed yield (SY) and final aerial biomass (FABM) in the 2 rain-fed environments. Canopy temperature (CT) at MI (26.7°C) was lower than at CRF (30.8°C) and MRF (36.6°C); the heat stress effect increased with the drop in plant water content in the driest environment (MRF); CT was negative and significantly associated with ψ and π at MRF. The high CT also had a significant effect in the FABM and SY, and its components; high CT reduced SY, FABM, number of normal pods.m^-2 (NP.m^-2) and weight of 100 seeds (W100S) by 12.5, 10.7, 10.2 y 3.4% for each ºC (^-1ºC) increase in CT, respectively.

Palabras clave : water; osmotic and turgor potentials; osmotic adjustment; heat; canopy temperature; irrigation; rainfed.

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