Effects of Germination on Cotyledon Nitrogen, Starch, Reducing Sugar, and Growth of Lima Seedlings
- D. A. Hegwood and
- T. P. Gaines2
Poor seedling establishment which frequently reduces stands and causes uneven seedling growth in lima bean (Phaseolus lunatus L.) plantings points up the need for research to identify those changes occuring during the seedling establishment phase. This research is needed to show how these changes are associated with early seedling growth. Accordingly, cotyledons from seedlings of two lima bean cultivars, ‘Nemagreen and Jackson Wonder,’ were compared during pre- and postemergence for changes in total N, protein N, nonprotein N, starch, reducing sugars, and seedling growth.
Cotyledons of Jackson Wonder were significantly higher in total N than Nemagreen because of the protein N fraction. The nonprotein N fraction did not differ between cultivars.
The proteinmonprotein N in Nemagreen approached 1 on the sixth, seventh, eighth, and ninth day after planting. Maximum decrease of protein N and a corresponding maximum increase of nonprotein N occurred on the fourth, fifth, sixth, and seventh day for each cultivar. A net decrease in total N in cotyledons occurred during postemergence.
Reducing sugars were present in cotyledons of resting seed and developing seedlings but did not differ in amount between cultivars.
The period of most rapid starch depletion and cotyledon weight loss occurred during postemergence and wasaccompanied by rapid increases in top dry weight.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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