Fruit cracking in Cereus peruvianus,a new cactus crop

Summary

Fruit of Cereus peruvianus (L.) Miller, a newly developed cactus crop, is subject to cracking. Fruit growth follows a double sigmoid curve, with a significant size increase in the first and third stages and moderate increase in the middle stage. Peel and seed grow in the first two stages, while pulp growth and maturation (e.g. peel colour change and stretching, sugar accumulation, fruit softening) occur in the final stage. Sensitive, moderately sensitive, and tolerant clones are subject to 100, 50–60 and 6–9% cracking, respectively, correlated to relative growth rate of the pulp in the third stage. Fruit cracking, lengthwise splitting of the peel, and exposure of the pulp occurred in fully mature fruits towards the end of their growth. Continuous monitoring of fruit growth revealed expansion and cracking during the day and shrinkage during the night, as expected for CAM plants. Cracking was not correlated with the threshold cracking turgor, which declined during ripening in all clones. GA₃ sprays during colour break reduced cracking in the two most susceptible clones to 20% and 60%, while paclobutrazol increased cracking. Cracking rates were the same in two ecozones differing in salinity, temperatures and relative humidity. It is suggested that breeding and hormone treatments could reduce cracking significantly.