FRUIT GROWTH DINAMICS IN SWEET CHERRY (Prunus avium) CULTIVARS WITH HIGH, MODERATE AND LOW SUSCEPTIBILTY TO CRACKING

Abstract

Fruit crack resistance is a key issue for sweet cherry breeding programs in Chile and worldwide. However, the physiological mechanisms involved in genetic differences to cracking susceptibility have not been fully studied. The objective of this research was to study the dynamics of fruit growth on sweet cherry
cultivars with low, moderate and high susceptibility to cracking. Both the absolute diameter growth rate (TCAD, mm d-1 fruit-1) and the mass growth rate (TCAM, gr d-1 fruit-1) were estimated in ´Bing` (high susceptibility), ´Stella` (moderate susceptibility) and ´Kordia` (low susceptibility) sweet cherry
cultivars, 30 to 79 days after bloom (DDF). Simultaneously, the cracking index (IP, %) and the water uptake rate (TAA, mg H2O h-1 fruit-1) were estimated after fruit immersion in distilled water for 5 hours. In ´Bing` and ´Stella` cultivars, cracking damage was observed from 51 DDF, whereas in ´Kordia` it was
observed from 72 DDF. From 51 to 58 DDF, TCAD and TCAM in 'Bing' and 'Stella' fruits were significantly greater than those from ´Kordia`. In ´Kordia`, maximum TCAD and TCAM values were reached at 72 DDF. A positive relationship between TCAM and TAA was found for ´Bing` (R2 = 0.60; p < 0.05) and ´Stella` (R2 = 0.90; p < 0.01) cultivars. It was concluded that fruit growth pattern differs among crack-susceptible and crack-resistant cultivars. Therefore, the analysis of fruit growth dynamics becomes a useful decision-making aid to select crack-resistant sweet cherry varieties.