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Abstract

Radish producers loose a proportion of their crop due to cracking; water status is believed to be an important factor affecting this. Current work investigates the effects of changes in soil water potential on the physiology and cracking rates in radish.

Description

Root splitting in radish (Raphanus sativus) is a fundamental problem for growers with losses ranging between 5 and 30%. Despite both economic and technical requirement for knowledge in this area the causes of root splitting in radish have yet to be fully explained and there is a lack of information and scientific investigation in this area. The aim of this project is to investigate the causes of root-splitting and provide growers with recommendations of best practice growing and storage conditions for the main commercial types of radish. This project will also evaluate different cultivars for their resistance to splitting and establish the physiological characteristics of particular radish which are most resistant to splitting.

Previous studies of splitting in radish, carrot, kohlrabi and potato suggests that both pre and post-harvest conditions may have significant effects on splitting. Initial investigations in this project will concentrate on pre-harvest factors; primarily the effect of soil water content and the timing of irrigation stress. Radish is a short duration crop with high growth rates and therefore the correct use of irrigation and an adequate water supply is thought to be fundamental to successful radish growth. To test this radish plants will be grown in pots in the glasshouse and exposed to a range of soil moistures at defined growth stages. Initial studies into irrigation frequency compared plants irrigated to the same gravimetric water potential daily, every other day, every 4 days and every 8 days. Initial results have shown irrigation has a significant effect on water content (P=0.017) and weight (P=0.027) at harvest which demonstrates that irrigation does affect the radish composition. However, these early investigations showed irrigation frequency did not have a significant effect (P=0.912) on splitting. Further investigations will be carried out to determine the role of irrigation and soil moisture content on root-splitting.

In addition to the investigations into the pre-harvest factors the project will also be investigating post-harvest factors such as the effect of storage relative humidity and temperature on splitting. Experiments will also investigate cultivar differences to establish which are most resistant to splitting under different conditions. The cultivars will be investigated physiologically, using sectioning & staining methods and scanning electron microscopy (SEM), to identify traits which make them more resistant to splitting. Once key traits in the resistant plants have been identified this can be used to screen new cultivars. It is hoped this this research work will lead to a greater understanding of the physiological basis of splitting, allowing growers to grow radish with less waste.