Effects of Population Density and Nitrogen Rate in Ultra Narrow Row Cotton

William T Molin,Josie A Hugie

doi:10.3814/2010/868723

Abstract

A field study was conducted to investigate the effects of population density and nitrogen rate on yield, growth, and fiber response of ultra narrow row (UNR) cotton. Stand loss occurred at densities greater than 22 plants <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mtext>m</mml:mtext><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> and nitrogen rates greater than 56 kg <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>ha</mml:mtext></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> and stand loss exceeded 20% at harvest. Seed cotton yields were similar across populations and rates of 56, 112, and 168 kg <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>ha</mml:mtext></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>. Nitrogen rates greater than 56 kg <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>ha</mml:mtext></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> resulted in greater vegetative growth based on increased plant height and number of nodes. These results indicate that populations of 22 plants <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mtext>m</mml:mtext><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> and nitrogen rates of 56 kg <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>ha</mml:mtext></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> were sufficient for maximum yields in UNR cotton under our conditions. However, at higher nitrogen rates, boll formation increased at lower nodes with no corresponding change in yield. Higher nitrogen rates may promote earliness and distribute yield across more fruiting sites.

Highlights

Ultra narrow row (UNR) cotton production has been proposed as an economical means to increase cotton production efficiency (Atwell et al [1], McFarland et al [2])
These results indicate that populations of 22 plants m−2 and nitrogen rates of 56 kg ha−1 were sufficient for maximum yields in ultra narrow row (UNR) cotton under our conditions
UNR yields were equal to or exceeded wide row (WR) yields in some cases (Bader et al [4], Cawley et al [5], Gwathmey et al [6], Jost and Cothren [7, 8], Reeves et al [3], and Wiatrak et al [9]) whereas no yield advantage was reported by others (Bednarz et al [10], Boquet et al [11], Boquet [12], Clawsen et al [13], Jones et al [14], Rinehardt et al [15])

Summary

Introduction

Ultra narrow row (UNR) cotton production has been proposed as an economical means to increase cotton production efficiency (Atwell et al [1], McFarland et al [2]). Advantages of a UNR production system include earlier crop development, reduced costs from late season insect control, and in some cases, increased yields ( McFarland et al [2]). Concerns regarding management of rank growth and weed control in ultra narrow rows have been abated by development of plant growth regulators and herbicide resistant cultivars (Atwell et al [1], Reeves et al [3]). The yield advantages of UNR cotton have been inconclusive. The uncertainty of a yield advantage of UNR cotton has led to research on identifying appropriate nitrogen rates and population densities to improve yields

Objectives

Methods

Results

Conclusion