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This article in AJ

  1. Vol. 74 No. 5, p. 865-870
     
    Received: May 4, 1981
    Published: Sept, 1982


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doi:10.2134/agronj1982.00021962007400050023x

Cultivar and Seeding Rate Effects on Several Physical Characteristics of Kentucky Bluegrass Turf1

  1. A. D. Brede and
  2. J. M. Duich2

Abstract

Abstract

The growth habit and plant dimensions of Kentucky bluegrass (Poa pratensis L.) can be affected by the management factors imposed. This study was initiated to learn the effects of seeding rate and cultivar on several physical characteristics of Kentucky bluegrass turf and to develop and evaluate techniques for measurement of these characteristics under turf field conditions (a line, mixed, mesic, Hapludalf soil). An optical enlargement technique was used to measure leaf angle, leaf-fold angle, sheath-axis width, leaf width, and leaf length of ‘A-34’, ‘Baron’, ‘Bonnieblue’, ‘Newport’, and ‘Pennstar’ Kentucky bluegrasses. An overhead projector (the type commonly used in classrooms), mirror, and protractor screen enlarged the plant image 10 to 20 times enabling 1-degree and 0.05-mm resolution. A Noer profile sample3 (inner dimension, 13 ✕ 76 mm) was compared to three, round tools and found acceptable for sampling population densities if the loose tillers were included in the count. Because counting was easier and quicker, and plugs were returnable to the plots with minimal disturbance, the Noer tool proved advantageous. A technique was developed for estimating seedling blade density, given a few standheight measurements.

Seeding rate had a positive effect on leaf angle, while the percent loose tillers per sample plug (an indicator of nonvertical tiller orientation), green leaves per tiller, sheath-axis width, and leaf widths were negatively affected by seeding rate in the year after establishment. Stand densities converged to a mature density over five growing seasons. The convergent density was affected by cultivar and cutting height.

Of the cultivars examined, A-34 had the highest tiller density throughout the test, fewest green leaves per tiller, and narrowest leaf angle and blades. Baron possessed the most brown leaves per tiller, and widest sheath-axis width (equal to Bonnieblue). Bonnieblue had the most green leaves per tiller, and lowest mature tiller density (equal to Pennstar). Pennstar had the most loose tillers per sample plug, widest leaf angle, and the most narrow sheath-axis width.

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