Assessing irrigation scheduling by FAO method using soil-plant atmosphere water stress indicators on four orange cultivars

摘要

Numerous citrus cultivars are cultivated in Tunisia. The lack of information on water requirements under local conditions and the possible varietal differences in the response to soil water status is noticed. This study aims at assessing the irrigation scheduling using FAO method and crop coefficients, under local conditions for different orange cultivars. An experiment was carried out on a navel orange [Citrus sinensis) drip-irrigated orchard; located in the Technical Citrus Center, north-east of Tunisia. Irrigation scheduling was developed using climatic data measured in situ during the previous 10-days. Water status was assessed monthly by measurements of soil water content and midday stem water potential during the year 2014 for four orange cultivars: 'Washington navel', 'Lane Late', 'New Hall', 'Navel Late'. Results showed that annual ETo was 1243 mm, precipitations were 413 mm and total applied irrigation amount was 716 mm. Stem water potential values varied between -0.7 MPa and -2.3 MPa. 'Lane late' seemed to be the most sensitive to summer conditions. Punctual water deficits occurred in summer despite of the applied irrigation. A discussion on irrigation scheduling is proposed on the basis of the seasonal variations of measured climatic and microclimatic parameters, stem water potential, and soil water content.