Estimation of Spring Wheat Leaf Growth Rates and Anthesis from Air Temperature¹

Abstract

Seasonal variability in climate within and between the major spring wheat (Triticum aestivum L.) growing regions of the world causes large differences in plant development patterns. A major need of models attempting to describe crop growth as a dynamic process is an evaluation of phenological development. Researchers modeling growth and yield would benefit from a meteorologically-based phenological index that accurately and reliably predicts the development stage. The objective of this study was to develop capability to estimate leaf growth rate and crop growth stage from planting to an thesis under variabie management and climatic conditions. Aboveground morphological entities of 16 hard red spring (HRS) and 3 durum (T. durum Desf.) wheats were rated in Haun scale designations in seven field trials grown on Williams loam (fine-loamy, mixed Typic Argiboroll). These designations were regressed with growing degreedays (GDD), ph()ltothermal units (PTU), and days (DAYS) after emergence. Time to emergence did not differ among cultivars within a trial. Among the seven trials, emergence occurred 7 to 15 days after planting; accumulated GDD ranged from 94 to 138, and averaged 106. Eighteen of the cultivars produced eight leaves, 'James' produced seven. Main-stem phyllochron interval was 73 GDD for the HRS cvs. Butte and Waldron combined for analysis, and about fl1 GDD for either "other" eight-leaved HRS cultivars or for the durums combined for analysis, and for James. The R 2 value for any combined analysis was no less than 0.970**, significant at the 0.01 level. Soil water level and fertilizer N rate had no effect on main stem development rate, but did affect the maximum number of tillers produced per plant. The GDD accumulated per plant growth unit from emergence to anthesis (leaves plus four stages after expansion of the flag leaf) was the same as from emergence through full expansion of the flag leaf. Precision of estimatiag growth rates and stages with GDD was the same as with PTU, and both were superior to DAYS.

Morphogenesis in guinea grass pastures under rotational grazing strategies

“…and when variations positive of temperature are sensed by the apical meristem, there is increase in the leaf elongation rate (Peacock, 1975). Duru & Ducrocq (2000) observed significant increases in leaf appearance rate and in the number of leaves with changes in the temperature, which indicates that this environmental factor is one of the most important in leaf appearance rate control (Bauer et al, 1984).…”

Variação e associação de características ligadas a formação do grão de genótipos de trigo

“…Os graus dias acumulados (GDA) foram utilizados como escala de tempo durante o enchimento do grão, porque a taxa de desenvolvimento da planta de trigo é determinada, predominantemente, pela temperatura (Bauer et al, 1984). No cálculo dos graus dias utilizou-se 5°C como temperatura base.…”

Agronomic and Physiological Responses of Rice (<i>Oryza sativa</i> L.) under Different Water Management Systems, Fertilizer Types and Seedling Age

“…However, the differences were not significantly different. Water stress appears to have an impact on phyllochron, but only at extreme stress [21] [22]. [9] found that rice plants experience …”