Environmental and Cultivar Effects on Height-to-Node Ratio and Growth Rate in Acala Cotton

Abstract

Cotton (Gossypium hirsutum L.) yield is influenced by the balance between vegetative and reproductive photosynthate demands. We evaluated plant measurements that detect this balance with the objective of developing effective management tools. The effects of water stress, mepiquat chloride (MC; 1,1‐dimethylpiperidinium chloride), and cultivar on this balance were evaluated. Plant height is more sensitive to stress than is number of nodes, so that the ratio of height to number of nodes (height‐to‐node ratio or HNR) provides a useful, field‐implementable measure of integrated source‐sink balance before anthesis. The rate of increase of height as a function of increase in number of nodes (growth rate or GR) provides a measure of the present state of the balance. Prior to anthesis HNR and GR provide a measure of source strength and accurately detect the ability of crops to sustain vegetative growth as affected by various plant stresses. At maturity, HNR provides an integrated measure of the crop's overall stress level and balance between vegetative and reproductive growth. Research Question Cotton's response to various environmental factors suggests that the relationship of plant vegetative growth, particularly height and node development, to these environmental factors provides useful indices for crop management. The ratio of plant height to number of main stem nodes, or height‐to‐node ratio (HNR), and the rate of change of plant height with respect to number of mainstem nodes (MSN), or growth rate (GR), serve as such indices prior to anthesis, particularly in the semi‐arid West, where relatively precise water management is possible. These indices can be used to precisely measure the balance between vegetative and reproductive growth. Reference values for HNR and GR have been established for Acala cotton. The objective of this study was to determine the effect of cultivar and environmental factors, particularly water stress and plant growth regulators, on these indices. Literature Summary Research conducted to understand the relationship between vegetative and reproductive cotton growth has engendered studies on the competitive nature of this relationship and its source‐sink interaction. Methods of controlling vegetative growth and development for the benefit of reproductive growth have been explored using irrigation and N management as well as growth regulators to moderate vegetative development. Studies reported in the literature support the concept that, during the early season, the rate of nodal development in cotton is less affected by environmental stress than is the rate of growth in height. Leaf removal experiments involving removal of one or both cotyledons and removal of zero, one, or two first true leaves at varying days after emergence indicate that many removal combinations significantly affect plant height, whereas only the most severe removal combinations significantly affect number of MSN. In irrigated production systems, delaying the first irrigation significantly reduces plant height. Study Descript...

UAV-Based LiDAR for High-Throughput Determination of Plant Height and Above-Ground Biomass of the Bioenergy Grass Arundo donax

“…Crop height is recognized as one of the most important components of AGB and yield in biomass crops [6,7]. Height can be reduced by environmental stress and can therefore be used to separate drought sensitive from drought tolerant crops [8,9]. Traditionally, crop height and diameter are measured manually with graduated poles and measuring tapes; this is difficult to do without canopy disturbance in the central region away from plot edges of tall (3.2 to 4.2 m) A. donax plants with their typically high shoot density.…”

Interactions of Single Mepiquat Chloride Application at Different Growth Stages with Climate, Cultivar, and Plant Population for Cotton Yield

“…Although studies have shown a common response of cotton to MC in terms of reduced internode length, reduced overall plant height, and more compact plants (He et al, 1984; Kerby, 1985; Reddy et al, 1996; Zhao and Oosterhuis, 2000; Siebert and Stewart, 2006), yield responses have ranged from positive (York, 1983a; He et al, 1984; Kerby, 1985; Li et al, 1986; Cathey and Meredith, 1988; Kerby et al, 1998; Biles and Cothren, 2001; Johnson and Pettigrew, 2006; Wilson et al, 2007) to negative (York, 1983a, 1983b; He et al, 1984; Cathey and Meredith, 1988; Zhao and Oosterhuis, 2000; O'Berry et al, 2009; Ren et al, 2013) to none (He et al, 1984; McConnell et al, 1992; Gwathmey and Craig, 2003; Dodds et al, 2010; Ren et al, 2013).…”

1-Methylcyclopropene Effects on Field-Grown Cotton: Morphological Characteristics and Yield

“…Height-to-node ratio (H:N) is the ratio between total plant height (measured from the cotyledons to the top terminal of the plant) and total number of nodes (including both monopodial and sympodial nodes). It provides an integrated measure of the crop's stress level and source-sink balance (Kerby et al, 1998). Across years and growth stages, results showed that H:N ranged from 3.7 to 4.7 cm and 4.0 to 4.7 cm for the dryland and irrigated studies, respectively (Tables 4, 5, and 6).…”