Study of Total Non-Structural Carbohydrates' and Macronutrients Influence on Pecan Yields

Study of Total Non-Structural Carbohydrates' and Macronutrients Influence on Pecan Yields

Pecan yields vary substantially from one year to the next due to a number of environmental and management factors including the alternate bearing nature of the pecan tree. Carbohydrates are a direct product of photosynthetic activity, and it is accepted that the alternate bearing trait in pecans is directly correlated to the amount of carbohydrates synthesized and how these are distributed within the tree. The objective of this work was to study (for the first time) the behaviour of carbohydrates and mineral reserves in different Australian pecan tree organs (leaves, trunk and exposed lateral roots) through the monthly measurement of total non-structural carbohydrates (TNSC), soluble carbohydrates and the macronutrients nitrogen (N), phosphorous (P) and potassium (K), with an emphasis on the role that these parameters played in yields. The concentration of carbohydrates in the trunk steadily decreased from spring to early summer, and subsequently increased to a peak in autumn, then slowly declined during winter. A minimum was achieved in June, coinciding with the start of the Australian winter. The relationships between carbohydrates and yields were established for the months of September and October (late spring), and June of the current season (early dormancy), coinciding with early dormancy with subsequent yields. This is an important finding suggesting the potential use of carbohydrates in the trunk during winter and spring. As indicated by the significant correlations obtained in spring and winter, this research demonstrates potential for the measurement of carbohydrates to become part of the monitoring regime to assess tree health and aid crop forecasting. This study has also highlighted the relationship between TNSC, nitrogen and phosphorous in leaves, with subsequent yields suggesting the use of leaf testing early in the season to assess nutrient status and yield potential. Further work to quantify the contribution of carbohydrate storage and nutritional status to yields is justified.

File reproduced in accordance with the copyright policy of the publisher/author.