Dynamics of spatial and temporal growth of the root system of grapevine (Vitis vinifera L.) under nitrogen levels in sandy soil in subtropical climate

Abstract

• N addition promotes the increase in the surface area of live fine roots. • Fine root production is higher in grapevine flowering stage. • N concentration in leaves is promoted by the increase in the fine roots. • Total number of dead and mortality of fine roots is increased by the addition of N. Nitrogen (N) supply to the soil via fertilization can influence important processes of the root system growth, which can increase N uptake and, consequently, the shoot growth. In this context, the study aimed to evaluate how the application of N levels can affect the dynamics of spatial and temporal growth of the root system of grapevines ( Vitis vinifera L.) in sandy soil and subtropical climate. ‘Alicante Bouschet’ grapevines, grafted on ‘Paulsen 1103’ rootstock, implanted in 2011. The N addition were: Low N: control (without the N addition; 0 kg N ha −1 year −1 ); Medium N (40 kg N ha −1 year −1 ); and High N (100 kg N ha −1 year −1 ). The study was carried out during 2016/17 and 2017/18 crop seasons. N concentration in the leaves and morphological parameters of fine roots were evaluated using the minirhizotron technique. The addition of Medium N and High N significantly increased the values ​​of the total surface area of ​​live fine roots and the total number of live and dead fine roots, at 0-20, 20-40 and 40-60 cm soil depth, in both crop seasons evaluated. The addition of Medium N and High N also directly influenced the production rates of live fine roots, with patterns of seasonal changes, especially increased in the flowering stage of the grapevines. This occurs due to the increase in the physiological demand of growing plant tissues, such as new roots, leaves and fruits.