Seasonal vine nutrient dynamics and distribution of shiraz grapevines

Abstract

Context and purpose of the study ‐ The nutrient reserves in the grapevine perennial structure perform a critical role in supplying the grapevine with nutrients when demand cannot be meet by root uptake. The seasonal changes in these reserves largely depend on the developmental stage and the associated growth requirements of grapevines. These stored reserves are influenced by environmental conditions and vineyard management practices, such as production levels and water availability.The aim was to assess the nutrient dynamics of a major wine grape variety grown in Australia, for determining the key nutrient uptake periods and to understand the mobilisation patterns in a season.

Material and methods ‐ The own‐rooted 10 year old Shiraz vines utilised for the trial were located in the Riverina, being a warm grape growing region. Uniformly sized vines were selected for 11 excavation dates with four replicates from bud‐burst to leaf‐fall. The above ground section of the vines were separated into different parts, with the number of tissues varying with the destructive harvest dates. The below ground section of the vines were obtained in an allocated area (6 m2/vine) and were excavated to a depth of 1 m, the roots were separated into rootstock and three root sizes. The sub‐ o samples of each tissue were freeze dried and the remaining tissues were oven dried at 70 C, for both procedures the dry weight (DW) was recorded. For the nutrient analysis the tissue samples were ground, and nutrients were determined with an N analyser and an ICP‐OES.

Results ‐ The annual organs showed the highest N concentrations in spring, with the leaves 2.5 % and inflorescences with 3 %, but shoot N concentration increased again at the end of the season to 0.7 % DW. Root N concentrations are at least double the other perennial sections, these reserves decline early in the season and were replenished by leaf‐fall. The changes in concentrations for perennial sections are similar for the other macro nutrients, while they differ for Ca and S in the annual tissues. The N content of the perennial structure declined considerably until flowering, with a sharp increase after harvest. The majority of the N uptake occurred four weeks before flowering and four weeks before veraison, more than half the N of the vinewas allocated to the annual organs at harvest. Other macro nutrients show a pattern of decline and replenishment in the roots and wood and most nutrients were taken up predominantly four weeks prior to flowering. The amounts of nutrients allocated to the perennial structure and annual parts varied between the nutrients, the understanding of the nutrient dynamics will led to an optimisation of nutrient status and supply for grapevines.