Identificação de características agronômicas e fisiológicas relacionadas com a tolerância à seca em mandioca

Abstract

Aiming to study the effect of drought on contrasting varieties of cassava and identify sources of drought tolerance, two experiments were conducted at Embrapa Cassava and Tropical Fruits, in Cruz das Almas, Bahia, Brazil. The first study evaluated 28 varieties, selected as contrasting for drought tolerance. The following traits were evaluated: plant height, leaf area, length of the stem without leaves, leaf retention, productivity, stomatal conductance and leaf temperature. At all times, the evaluated traits were decreased in response to low values of soil water potential. The lower sensitivity of water deficit was observed in genotypes ‘Engana Ladrão’, ‘Fio de Ouro’ e ‘Pretinha V’. In another experiment four contrasting cassava varieties were used: Engana Ladrão, Tai 8, Pretinha V e COL 1468. A complete randomized design were used, with five replications. The two treatments were: T1 - control, T2 - water deficit. The evaluations were: Soil moisture, plant height, leaf area, leaf number, leaf growth, stomatal conductance, transpiration, leaf temperature, leaf relative water content, osmotic content, dry matter and relative growth rate. The varieties ’Engana Ladrão’ and ‘Tai 8’ had greater efficiency in the mechanism for drought tolerance than ‘Pretinha V’ and ‘COL 1468’. The traits used were able to identify the cassava varieties tolerant to drought.