Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → États-Unis → 1981 → THE EFFECT OF PLANTING DATA AND ENVIRONMENT ON THE PHENOLOGY AND MODELING OF GRAIN SORGHUM, SORGHUM BICOLOR (L.) MOENCH

Kansas State University (1981)

THE EFFECT OF PLANTING DATA AND ENVIRONMENT ON THE PHENOLOGY AND MODELING OF GRAIN SORGHUM, SORGHUM BICOLOR (L.) MOENCH

SCHAFFER, JAMES ALLEN

Titre : THE EFFECT OF PLANTING DATA AND ENVIRONMENT ON THE PHENOLOGY AND MODELING OF GRAIN SORGHUM, SORGHUM BICOLOR (L.) MOENCH

Auteur : SCHAFFER, JAMES ALLEN

Université de soutenance : Kansas State University

Grade : Doctor of Philosophy (PhD) 1981

Résumé
Grain sorghum is becoming an increasingly important feed grain in some of the semi-arid regions of developed countries as well as maintaining its position as an important food crop in the less developed areas of the world. This crop has been the subject of innumerable research papers and much information is available about the growth and development of sorghum. However, the infant field of computer simulation requires more detailed information than that which is readily apparent in many of those studies. Using serial plantings, an attempt was made to subject grain sorghum to a wide range of climatic conditions at various growth stages within the same geographic location. Several planting dates with four different relative maturity hybrids were seeded at five locations from Temple, Texas to Manhattan, Kansas. Three major growth stages were studied : GS1—the time between emergence and floral initiation ; GS2—the time from floral initiation to anthesis ; and GS3—the time between anthesis and physiological maturity. GS3 was the stage of most concern in this study. Generally, early planting retarded early plant development, had little effect on the duration of panicle development, increased the number of leaves produced, and subjected the plant to high temperatures during GS3. Later planting hastened vegetative development, reduced leaf numbers, and extended the grain filling period because of cooler temperatures in the fall. This study showed that GS3 was temperature dependent and that development continued at a faster rate with a rise in temperature up to a point within which most temperatures fell (38 C). Also, grain filling was simulated down to a temperature as low as 1 C. Grain sorghum was not responsive to the same temperature limits throughout its life cycle. During early growth, low temperatures were more detrimental to development than at some of the later stages, and higher temperatures seemed to be least detrimental during the grain filling period. A heat unit system was developed from the data collected in this study and used to predict the duration of GS3. A heat unit system using 38 C as its maximum temperature and 1 C as its minimum and base temperature was the best predictor of the duration of GS3. In order to develop a simple model for predicting physiological maturity, one value for the accumulated heat units was determined for all hybrids, dates of planting, and locations studied. When 741 heat units were accumulated after anthesis, physiological maturity was predicted. This new model was tested against a previously developed dynamic grain sorghum growth model. Using individual plant data, the modeled dates of phenological events were analyzed against the actual dates of occurrence by regression analysis. The new model was found to be a considerable improvement over the previous method of predicting physiological maturity in grain sorghum.

Search Oxford Libraries Online (SOLO)

Page publiée le 6 avril 2015, mise à jour le 2 novembre 2018