How and when potential yield disappeared

Abstract

Every year, after the inflorescences counting in spring, a certain loss in the number of clusters was observed at the harvest. Until now, researchers thought that the greatest loss, regarding final cluster number, occurs at the end of flowering. For this reason, the research was conducted to determine in which phenophase the loss occurs and how high the level of loss is. The experiment was established in a vineyard with the varieties Petra and Liza. Thirty days before flowering, the potential crop load was established. From that point, at certain intervals during the growing season, the loss in the inflorescences (clusters) number was recorded. For this purpose, the same vines, shoots аnd inflorescences (clusters) were always used, taking into account their position on the cane. During the study, it was found that the loss of shoots was 32 % and 33 % for Petra and Liza respectively. The share of shoots carrying inflorescences in loosed shoots was 36 % and 33 % for Petra and Liza respectively. In the case of Petra, the total loss of inflorescences (clusters) was 46 % and in the case of Liza it was 36 %. This study gives information to scientists, that greatest loss happens before flowering and that this loss is almost half of the total loss! This was a shocking fact, but it was found that the yield loss was caused by adverse weather conditions in the observed period. Crop loss at the end of flowering was primarily caused by necrosis of the whole inflorescences or its parts.