THE MEASUREMENT AND DYNAMICS OF SOYBEAN SEED GROWTH IN A CONTROLLED ENVIRONMENT (FRUIT RESPIRATION, RATE)
Abstract
The association between seed growth and the seed's morphological position on soybean (Glycine max. (L.) Merr.) plants grown in a controlled environment were evaluated. Methodology studies were done to determine the accuracy of indirect measures of seed mass and seed growth rate (SGR). Respiratory CO(,2) evolution and O(,2) consumption, expressed on a unit mass basis, as well as the external measurement of pod diameter, were related to seed mass with r('2) values of 0.87, 0.93, and 0.98, respectively. Pod diameter was used to estimate SGR and the rates obtained in this way gave a reasonable prediction of the actual rates as determined by means of destructive sampling. Seed growth rates ranged from a high of 8.31 mg.seed('-1).day('-1) to a low of 5.46 mg.seed('-1).day('-1) and the observed differences were consistently related to the seed's sequential position within the fruit, the fruit's age ranking order at the node, and with plant canopy level. Seed dry mass for fruits of similar age correlated positively with node number (r = 0.57), and negatively with the fruit's age ranking at the node (r = -0.66) and the seed's sequential position within the pod (r = -0.31). Pod length for three seeded pods related positively to seed size (r = 0.64) and negatively to pod age ranking at the node (r = -0.70). Both relations tested significant at the 0.01 level. Inspection of partial regression coefficients indicated that age ranking at the node made the greatest contribution towards observed differences in dry mass and SGR. When controlling for other variables, number of seeds per fruit and number of fruits per node did not have a significant effect on SGR. An explanatory model involving variables that describe the seed's morphological position on the plant was developed by which 65% of the observed differences in dry mass for seed with a common anthesis date, could be explained (R = 0.81).
Degree
Ph.D.
Subject Area
Agronomy
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