Fertility assessment in Vitis vinifera L., cv. Alvarinho

Abstract

Context and purpose of the study – The Portuguese wine production is characterized by wide yield fluctuations, causing considerable implications in the economic performance of this sector. The possibility of predicting the yield in advance is crucial as it enables preliminary planning and management of the available resources. The present work aims to study and evaluate two different techniques for the assessment of vine fertility.

Material and methods – Based on the fact that the number of inflorescences is established during the first year of the grapevine reproductive cycle and with the aim of evaluating grapevine fertility in cv. Alvarinho, two experimental procedures were performed. First, grapevine bud dissections were made during the dormant stage, in order to count the number of inflorescence primordia and assess the bud fertility potential. At the same time, grapevine canes were collected and placed in a growth chamber. Their development was monitored and, 25 days after, when the inflorescences attained the Separated Flower Buttons stage the fertility of each bud was recorded. In spring, using the same grapevines from where the samples were collected, fertility was assessed in the field and correlation between both was studied. Statistical analysis was performed including logistic and Poisson regression models for dependent data.

Results – Even using high definition observation equipment, the bud dissection technique was highly fallible, not allowing for correct identification of inflorescence primordia. Regarding the second methodology, no statistically significant differences were detected between the fertility observed in the growth chamber and in the field. These findings validate the success of the technique in assessing bud fertility at the pruning stage, 10 months before harvest.