Micrometeorological modeling and water consumption of tabasco pepper cultivated under greenhouse conditions

Abstract

Micrometeorological variables of tabasco pepper cultivated under greenhouse and drip irrigated conditions have not been presented to date in literature, especially the water consumption of these plants, in terms of crop evapotranspiration (ET_c) and crop coefficient (K_c). The determination of these variables is extremely important for the application of the correct amount of water to irrigated crops in these environments because PM FAO (56) standard methodology was idealized for outdoor environments. The objective of this work was to develop models of estimation of micrometeorological variables in greenhouse conditions and to determine the water demand, in terms of evapotranspiration (ET) and K_c, of the pepper (Capsicum frutescens L.), cv. Tabasco McIlhenny, drip irrigated using drainage lysimeters. The research was carried out in an experimental area located at the University of Sao Paulo (USP) in Piracicaba, SP, Brazil. The following micrometeorological variables were monitored: air temperature, air relative humidity (digital thermohygrometer) and evaporation (mini-pan) (EMT). Drainage lysimeters were used to obtain the ET_c and the reference evapotranspiration (ET_o) was estimated outside the greenhouse by the Penman Monteith (ET_oPM), Hargreaves and Samani (ET_oHS) methods and the class “A” pan method (ECA). It was concluded that the total value of mini-pan evaporation (EMT) inside the greenhouse was practically equal to ET_oPM, 5% lower than ET_oHS and 31% higher than ECA in the outdoor environment. ET values ranged from 0.28 to 2.42 mm day^-1 and total crop ET was 446.43 mm. The K_c values for the first pepper production cycle were: 0.17 in the initial phase, 0.76 in the flowering and fruiting phase and 0.39 in the harvest phase, for the second production cycle, the value of K_c was 0.50 at the harvest phase.