Rachis browning in tablegrapes

Rachis browning is considered the second most important postharvest problem of tablegrapes. The primary problem, control of decay, was extensively studied in recent years, often with minor attention to rachis browning. To the consumer, a green rachis is an indication of freshness, and hence, a brown rachis can be a major cause of consumer rejection and eventually fruit waste. The significant advantage of the sulfur dioxide technology in its various forms of application is that it can prevent both decay and reduce rachis browning. Such an advantage is partly why alternative control measures, which may be significant for control of decay, did not develop further. Understanding rachis browning starts with a description of methods to measure it. Dehydration is considered the primary cause of browning, and therefore, packaging and other technologies which decrease dehydration are discussed. Controlled and modified atmosphere technologies may have opposing effects on rachis browning, making it important to be familiar with the wider picture. It is also important to realise the effect of various other treatments in which rachis browning was measured, because it can hint on what has, and has not, a potential to reduce it. The effect of plant-growth regulators is discussed with special emphasis on the potential role of ethylene in enhancing rachis browning and ethylene antagonists in reducing it. It is suggested that controlling rachis browning may require dedicated treatments based on physiological and molecular mechanism of browning in combination to control of decay.