Kentucky Bluegrass Establishment for Seed Production

Introduction

Kentucky bluegrass was introduced into North America from Europe about 3 centuries ago. It is adapted to cool, humid climates. Kentucky bluegrass is a sod-forming perennial grass in which apomixis (formation of seed without fertilization) is a common characteristic. Kentucky bluegrass is used extensively in Eastern North America as a pasture grass and throughout Canada and the northern United States as a lawn grass. Canadian seed production for the period 1983-1986 averaged 89 000 kg, while imports were 2 383 000 kg.

Current recommendations for the production of Kentucky bluegrass is to establish the grass in a firm seed bed on land free of perennial weeds, preferably following a broadleaf crop. No economic return will be received in the year of establishment unless a companion crop is planted. A project was initiated at SIDC in 1993 to identify companion crops which provide an economic return in the establishment year without sacrificing seed yield in subsequent years.

How the Experiments were Done

Recommendation

• Use flax sown in wide row spacings as a companion crop
• Sowing the companion crop on a broadleaf crop stubble allows easier weed control with herbicides

Dormie Kentucky bluegrass was planted on May 4, 1993 on a 20 cm row spacing. Companion crops were sown on 40 cm row spacing, except canola which was on a 60 cm spacing. Plots were 2.4 m by 6.0 m in size. Irrigation was scheduled to maintain soil moisture at above 50% of field capacity in the top 30 cm.

The cover crops evaluated were GR397 flax, Keet canaryseed, Goldrush canola, Radley pea, Eston lentil, Indian Head lentil, and Nitro annual alfalfa.

The percent of sunlight penetrating the companion crop canopy and available to the grass seedlings was measured near noon on a clear day in early August. The measurement was taken using a 1m long light intensity meter.

All grain crops were harvested for seed when mature. The Indian Head lentils were harvested just after light measurements were taken. The alfalfa was cut on August 18 at 25% bloom.

A second small plot trial in 1994 evaluated the effect of two flax types (Linola^TM 947 and GR397) at three row spacings (20, 40, 60 cm) on the establishment of Dormie Kentucky bluegrass. The bluegrass was planted after the flax at right angles on 20 cm spacing at 1.5 kg/ha.

The flax was swathed September 6 and combined 13 days later. The straw was removed and the entire plot area was mown prior to freezeup.

Results

Less than 5% of full sunlight reached the bluegrass seedling under all cover crops except flax and canaryseed which allowed approximately 15% of sunlight through (Table 1). Bluegrass plants under the lentil and alfalfa companion crops were stunted and chlorotic due to insufficient light. Canary seed and flax have potential as companion crops because they allow greater light penetration to the juvenile bluegrass. Weed control is simplified as both crops can tolerate propanil (Stampede^TM) herbicide. Flax and canary seed both have small seed size which permits seeding to occur simultaneously with the bluegrass, or in a prior operation with little soil disturbance.

Yields of the respective companion crops and Dormie Kentucky bluegrass in the year following establishment are given in Table 1. Canary seed can not be recommended as a companion crop because of the reduced seed yield of Kentucky bluegrass the following year (Table 1). Pea and Eston lentil cannot be recommended because of lower yields resulting from the shading effect of these crops.

Further evaluation with flax as a companion crop indicated declining flax yields with increased row spacing (Table 2). Although not statistically significant, bluegrass yields were lower using the short statured, upright, early maturing line GR397 as compared to Linola^TM 947. The early, upright flax type produced a more competitive ground cover earlier in the season.Wide companion crop row spacings led to higher seed yield of Kentucky bluegrass than did narrow row spacings (Table 2).

Flax Companion Crops in the Rotation

Using flax as a companion crop requires that consideration be given to the crop grown in the year before establishment. Volunteer growth of a cereal crop could become a serious weed problem in a flax/Kentucky bluegrass mixture since control is difficult or impossible. Therefore a broadleaf crop, in which volunteer growth can be controlled, is suggested.