The effects of nitrogen and irrigation on timothy (Phleum pratense) grown for production of seed: II. Reproductive growth and yield of seed

Abstract

1. Plants of S.48 timothy were established on a 1 ft square (30 cm × 30 cm) pattern for production of seed. Plots at three levels of applied nitrogen, 0 (N0), 87 (Nl) and 261 (N2) lb N/acre (0, 97·5 and 292·5 kg/N ha) per annum were either irrigated to field capacity from 1 week before initiation of spikelets until 2 weeks before harvest, or not irrigated, during each of three years.2. Application of nitrogen caused earlier initiation and emergence of inflorescences each year, and earlier general anthesis in the first and third years. Irrigation generally had no effect on the date of initiation, but it prolonged the period of reproductive development and delayed the date of harvest by 2–5 days.3. The number of ears per plant was increased by the N1 treatment above the number produced by plants in the N0 treatment. In the N2 treatment the number of ears per plant was between the number in the N0 and N1 treatments in non-irrigated plots; in irrigated plots, plants in the N2 treatment sometimes had a lower number of ears than plants in the N0 treatment. The length of ears increased with the rate of application of nitrogen.