Alternate watering in soil vertical profile improved water use efficiency of maize ( Zea mays)

Abstract

A new method of irrigation was designed and tested for its biomass production and water use efficiency (WUE) in pot-grown maize. Maize plants were grown in pots with their roots vertically separated into two parts. A 5 cm layer of stone chips (diameter 3–6 mm) was used to separate the upper and lower parts so that capillary movement of water between the two parts was prevented without restricting root penetration. Watering and soil drying could be applied independently on either part of the soil column. Results showed that when water consumption was reduced by 20% (moderate soil drying) and 40% (severe soil drying) through extending the watering intervals, the alternate watering (AW), or drying, on either part of the soil column largely maintained its biomass production under moderate soil drying. In addition, AW outperformed bottom watering (BW) or surface watering (SW) in biomass production when the same amount water was consumed. Root development, as both root length and dried mass, was significantly enhanced. Significant increases in WUE and root to shoot ratio were observed as a result of the AW treatment. Rate of photosynthesis of AW under moderate or severe soil drying was enhanced when compared to BW or SW under similar soil drying treatments. The results also showed that total nutrient uptake, the K and N, and shoot biomass production were enhanced by alternate drying and rewatering in two parts in the vertical soil profile. We conclude that controlled AW in the vertical soil profile is an effective and water-saving method and may have potential to be used in the field.