Phylloxera infestation and the uptake and distribution of ¹³C and ¹⁵N tracers in grape vines

Abstract

In order to study the reason phylloxera (Daktulosphaira vitifolia Fitch) feeding on roots leads to decreased plant productivity, the uptake and distribution of ¹³C photosynthates and ¹⁵N in the grape vine 'Wuhe 8612' in response to phylloxera infestation were investigated. Phylloxera and grapevines cocultivated in pots were treated with ¹³CO₂ and 15N-urea. The plant weight, nitrogen concentration and accumulation, ¹⁵N utilization efficiency, Nitrogen derived from fertilizer (Ndff%), and carbon isotope ratio (δ¹³C) of different organs were measured. Phylloxera infestation significantly reduced grape weight, shoot length, and N concentration and accumulation in different organs, whereas it increased the ratio between N content of the of roots and above-ground organs. Phylloxera infestation reduced leaf and root nitrogen ¹⁵N utilization efficiency, by 24 % and 14 %, respectively compared to controls. Labeled leaves of infested plants took up rather more ¹³C and ¹⁵N and exported a substantial amount of these nutrients to roots. Labeled roots took up rather more ¹⁵N and exported a small amount of these nutrients to upper leaves. This study found that phylloxera infestation reduced ¹³C and ¹⁵N uptake in leaves and roots, but increased N and photosynthates, which were mostly distributed to the roots, but also to the upper leaves. These factors together led to weak grape vine growth.