Yield and Maturity of Ultra‐Narrow Row Cotton in High Input Production Systems

Abstract

Ultra‐narrow row (UNR) cotton (Gossypium hirsutum L.), with rows spaced <40 cm apart, has the potential to reduce the time to maturity as UNR as fewer bolls per plant need to be produced to achieve comparable yields to 1 m spaced cotton crops. The objective of this study was to compare the maturity and yield of cotton grown under UNR spacing with conventionally spaced rows in high‐yielding, high‐input production systems (>1800 kg lint ha−1). Six field experiments comparing UNR and 1 m spaced systems were conducted across a range of environments in Australia where yield on average was increased by 14.4% (P < 0.05) in UNR but the magnitude of this difference varied among experiments (3.7–38.8%). There were no differences in crop maturity (60% bolls open) between the systems. As expected, plants under the UNR system were smaller and produced fewer and smaller bolls. The higher yield under UNR was associated with a greater number of bolls per unit area. Although plants in the UNR crop had fewer fruiting branches and bolls per plant, these bolls did not mature earlier than those in the conventionally spaced crop. Lower boll retention was measured in the UNR crop and may be a key reason for the UNR crops maturing at the same time. The use of UNR may offer opportunities for growers to improve yields, but not for shortening the time of maturity in high yield high input systems. The use of the mepiquat chloride did not affect outcomes in this study.