Effects of irrigation water quality on vegetables Part 1: Yield and aesthetical appeal

Abstract

Research on the use of greywater for irrigation has focused attention largely on greywater quality and biomass of the crop, but not on the quality of edible vegetable crops, whereas aesthetical appeal of the vegetables determines the acceptance in fresh produce markets. Thus a field experiment was established at the Umtata Dam Research Station where combinations of cabbage and onion, spinach and beetroot, and carrot and lettuce were planted to coincide with four different planting seasons. Crops were irrigated with greywater generated from household activities such as bathing and dishwashing, diluted greywater (1:1 with potable water), and potable water from a tap stand. The yield and aesthetical appeal were measured. There were significantly higher yields and aesthetical appeal of cabbage from using diluted greywater. Onion yields were significantly higher when irrigated with greywater. Similarly, spinach had significantly higher yields but many leaves were infested with leaf-spot disease, which significantly lowered its marketability from greywater treatment. Beetroot yield was reduced by 47% (4.7 t ha⁻¹) when irrigated with greywater compared to the control and external quality was not affected by any of the three water treatments. Carrot also did not show any significant difference in yield, but carrots that were irrigated with potable water were significantly more appealing. Lettuce irrigated with diluted greywater was significantly more appealing than other treatments. Crops that were irrigated with greywater resulted in higher yields, but compromised the quality of the crop to meet fresh produce market requirements.

Keywords: aesthetical appeal, diluted greywater, irrigation, vegetables, yield