Crescimento vegetativo e eficiência do uso da água pela mandioca cultivar paulozinho sob restrições de reposição hídrica

Abstract

The cassava culture tolerates adverse edaphoclimatic conditions, such as high temperatures and soils with low fertility, however little is known about the effects that water restriction can cause on the initial development of the plant. Based on this context, the objective was to analyze the vegetative growth and water use efficiency by cassava cultivar Paulozinho under water replacement restrictions. The work was carried out in the greenhouse of the Federal University of Amapá, Campus Mazagão, Amapá. The experimental design was in randomized blocks with five replications and five treatments of water replacement restrictions, being: 7, 14, 21 and 28 consecutive days of water restriction, implemented seven days after the emergence of the shoots; and a control treatment (without water restriction). Until seven days after the emergence of sprouts and after the application of water restrictions, irrigations were performed daily in all treatments, applying 1 liter of water per pot. The drained volumes were collected two hours after irrigation to quantify the daily evapotranspiration. Plant growth was determined weekly using measures: plant height, stem diameter, number of leaves and leaf area. At 70 days after the emergence of the shoots (DAE), the plants were separated into stem, leaves (limbus and petiole), and roots, obtaining dry phytomass. Cassava cv Paulozinho cannot survive periods exceeding 28 consecutive days of water restriction, when they occur at the beginning of sprouting. The initial vegetative growth of cassava cv Paulozinho is not affected by water restriction of up to 21 days after emergence. Water replacement restrictions of up to 21 days at the beginning of the cv Paulozinho cassava cycle do not impair vegetative growth and dry phytomass production capacity until 70 days after the emergence of sprouts. It is recommended to carry out further studies with water deficit in the initial growth stage of cassava cv Paulozinho, to identify its effect on crop productivity