Evaluation rachis browning phenomena of 'Superior Seedless' vines grafted on different rootstocks during shelf life

Rachis browning phenomena during shelf life is an important issue faced by grapes trading. The experiment was carried out during two growth seasons (2017-2018) to evaluate the effect of Superior Seedless' rootstocks such as 'Freedom', 'SO4', '1103 Paulsen', and 'own-roots on rachis fruit clusters browning phenomena were tested during shelf life. Fruit cluster samples were harvested from commercial vineyard when total soluble solids reached 16 degrees Brix. Thereafter, bunches were stored at ambient temperature (26 +/- 1 degrees C and 45 +/- 1 RH% air relative humidity) for four days as a shelf life experiment. Samples selected everyday interval as for physical properties and chemical determinations. The results pointed out that the '1103 Paulsen' rootstock decreased the water loss percentage, rachis browning symptoms, and improved berries color hue angle. Moreover, a significant decline in enzyme activities of cellular walls such as polygalacturonase (PG; EC:3.2.1.15), and lipoxygenase (LOX; EC:1.13.11) monitored. Consequently, '1103 Paulsen' minimized the malondialdehyde (AMD) accumulation and cell membrane cellular ionic permeability during four days of shelf life. Lately, both browning enzymes PPO and PAL diminished. Thus, preserving the phenolic compounds accompanied by less browning incidence on fruit rachis during the shelf-life period. Overall, '1103 Paulsen' minimize the browning symptoms of 'Superior seedless' grapes were grafted on four rootstocks during shelf life stress/marketing.