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Title: ALLOMETIC RELATIONSHIPS IN FIELD-GROWN SOYBEAN

Author
item Reddy, Vangimalla
item PACHEPSKY, YAKOV - DUKE UNIVERSITY
item WHISLER, FRANK - MISSISSIPPI STATE UNIV.

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Allometric relationships in plants uncover size-correlated variations in form and development and characterize the relative growth of a plant part in comparison with a whole plant. Knowledge of ontogenetic allometric relationships in agricultural plants is of great use in developing crop simulators and in estimating crop parameters from remote sensing data. Data were collected on vegetative stages, plant height, stem weight, and leaf weight of 16 soybean cultivars on farms in Mid-south during 1993-1995 consisting of various soil types and environments. From this data we observed allometric relations between height and the vegetative stage, between stem height and stem mass, and between proportion of leaves in the total shoot weight and the vegetative stage. Water stress could be a modifier of these relationships. The proportion of leaf weight in shoot weight decreased linearly as the vegetative development progressed.

Technical Abstract: Allometric relationships in plants uncover size-correlated variations in form and development and characterize the relative growth of a part of a plant in comparison with a whole. Stable allometric relationships in ontogeny can be used as components of crop models and to estimate plant parameters that are difficult to measure. Our objective was to find whether there exist stable allometric relations in ontogeny of field-grown soybeans. We used field data on vegetative stages, plant height, stem weight, and leaf weight of 16 soybean cultivars measured on farms and on the experiment station of Mississippi State University in 1993-1995 growing seasons. The number of observed crops for each cultivar ranged from 1 to 14. Stem heights displayed linear log-log dependencies on the vegetative stage before and after some breakpoint stage which typically was between V4 and V6. Slopes of the log-log dependancies after the breakpoint stage were similar in all cultivars. Stem mass has a log-log linear dependancy on stem height. Slopes of these dependancies differed among cultivars grown in the same conditions and among crops of the same cultivar grown in different conditions. Water stress could be a modifier of these relationships. The proportion of leaf weight in shoot weight decreased linearly as the vegetative development progressed. Since ontogenetic relations are stable for a specific crop, they can be used to forecast vegetative development of this crop as soon as they are established.