Monitoramento de estresse hídrico no milho (Zea mays L.) irrigado na região semiárida.

Abstract

The field experiment was conducted in 1986 to study the general response of maize (Zea mays L.), "jatinam C3 anão" variety, subjected to four different levels of irrigation (100%, 75%, 50% and 25% of field capacity). This research was conducted at the field research laboratory which belongs to CPATSA/EMBRAPA, Petrolina-PE. The objective was to verify the possibility at monitoring the water stress in maize using a simple and more reliable technique that employs the principles of infrared thermometry. The experimental design consisted of a randomized block design with four irrigation treatments andthree replications. Each experimental unit occupied an area of 76,8 m2 (12 m x 6,4 m). The irrigation system consisted of furrows closed at their extremities and the amount of irrigation was vo1 umetrica 1 1y controlled by means of a simple water meter. The irrigation treatmens were applied after about thirty days of painting. Prior to the application of the irrigation treatments all the plots were maintained at the field capacity. Soil moisture, crop phenology and morphology, fresh and dry biomass, leaf area, stomatal resistence, air, leaf and canopy temperature data vie re collected during the crop cycle. The daily stress index, the thermal stress index and the canopy temperature variation were utilized in monitoring the water stress. The growth analysis was perfomed using the net assimilation rate.