Seed production studies in tall fescue (Festuca arundinacea Schreb.) cv. Grasslands Advance

Abstract

The effects of row spacing, row gapping, autumn nitrogen, and a plant growth regulator on seed yield and quality of tall fescue (Festuca arundinacea Schreb.) cv. Grasslands Advance were investigated in three different trials over two growing seasons. The first experiment involved a second year crop of tall fescue sown in December 2000 in 15 cm rows at 2.5 kg/ha on the property of Mr Don Hefter, Tai Tapu, Hudson Road, Greenpark (5 km from Lincoln). Row spacing’s of 15, 30, 45 and 60 cm were created by spraying glyphosate (Roundup 36% active ingredient) at 20 ml/litre water with a knapsack sprayer in July. Experiment two also involved a second year tall fescue crop sown in 2000 in 15 cm rows on the property of Mr Jim McCartney, Tai Tapu. In June 2002 part of the field was 'gapped' using glyphosate 360 (Roundup G2) applied to every second row. The third experiment involved a first year tall fescue crop at the AgResearch Seed Production Farm, Boundary Road, Lincoln. The experiment involved four row spacing’s (15, 30, 45 and 60 cm), three autumn nitrogen fertilizer rates (50, 100 and 150 kg N/ha) and the plant growth regulator (Moddus) at 2 L product/ha applied at 30% anthesis. The crop was sown on 28th November 2002 in 15 cm rows at a seeding rate of 8 kg/ha. Row spacing’s of 30, 45, and 60 cm were created from the 6 to 15th January 2003 by using a hand hoe.

In experiment one seed yield did not differ between row widths of 15 and 30 cm, but was significantly reduced at 45 and 60 cm row spacing’s. In experiment two un-gapped plots (15 cm sown row) had a significantly higher seed yield compared to gapped plots (30 cm between rows). However in both experiments it is suspected that the herbicide used to create the wider row spacing and gaps may have impaired fertile tiller production. In both experiments the treatments did not affect tall fescue seed quality (germination and TSW). However the mean germination of 65 and 73% for the row spacing and row gapping experiments respectively was poor, and most probably was a result of frost damage during seed development in December 2002. Seed size grading to remove small seed from both the row spacing (experiment 1) and row gapping (experiment 2) trials resulted in improved TSW and germination; however this improvement of seed quality was associated with the loss of nearly 40% of the original seed lot.

In experiment three the plant growth regulator (PGR) application had no effect on seed yield, but did marginally reduce lodging and stem length. The lack of response to the PGR for seed yield may have been because the crop was a first year stand, but also possibly because of the late application of the PGR. Autumn nitrogen rates of 100 and 150 kg N/ha did not increase seed yield over that of 50 kg N/ha. There was a significant interaction between nitrogen and row spacing, because at 50 kg N/ha, seed yield was greater at 15 and 30 cm row spacing’s. There was also a significant nitrogen, row spacing, PGR interaction because at 150 kg N/ha, seed yield at the 15 cm row spacing was greater in the absence of PGR. Row spacing, autumn nitrogen, and PGR had no effect on seed quality (germination, seed vigour and TSW) and there were no interactions.