DESTRUCTIVE HYDROTHERMAL FACTORS OF THE GROWING SEASON ONE MONTH BEFORE HARVEST, INCREASING THE LOSS OF APPLE FRUITS FROM "SUNBURN" DURING STORAGE

Abstract

Weather conditions affect both the resistance of apple fruits to physiological disorders during their storage, and the decrease in resilience to them. The damage of the fruits of susceptible apple cultivars by "scald" (browning of the skin) at the end of storage is influenced by weather conditions 30 days before harvesting them. In hot weather During the hot day and warm night, the fruits are more affected by "tan". Losses increase if the sum of the average daily temperatures >+10° C for the month before harvesting exceeds the threshold of 360-380°C. The analysis of the damage to the fruits by “scald "of susceptible new scab-immune columnar apple cultivars of the VNIISPK breeding – Vostorg, Poesia and Priokskoye at the end of their storage in various years (2014, 2016, 2018) showed a close dependence of this disorder on the conditions of humidification of the active growing season a month before harvest, expressed using the indicator of the conditional moisture balance, i.e. Selyaninov hydrothermal coefficient (SHC). The damage to fruits by "sunburn" directly depends on the level of SHC. The dependence is approximated by the second-order parabola equation. The equations for calculating the quantitative losses of apple fruits from "scald" (at the end of storage) under hydrothermal conditions for a month before harvesting are obtained. The correlation relations between the empirically obtained and calculated data are from 0.99 to 1. The tops of the parabolas reflecting the maximum calculated damage of fruits by "scald" at the end of storage in relation to the coordinate axes have maximum peaks – from 11.17 (Priokskoye) to – 15.21-15.24% (for Vostorg and Poesia, respectively) with a SHC corresponding to dry conditions – 0.68; 0.69 and 0.70 (Priokskoye, Poesia and Vostorg, respectively). The higher the SHC, the lower the dependence curve and the damage to the fruits by "scald". The calculated data can be interpolated, and the SHC can be used as one of the predictor indicators that affect the quality of fruits during storage.