International Journal of Horticulture, 2017, Vol.7, No. 12, 95-105
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Figure 13 Growth curve of yam (seed wt. 800 g, undisturbed)
Note: Growth curve of yam with seed weight 800 g when the growth is undisturbed as underground yam is not detached during the
experiment is shown in Figure 13. Ignoring the fluctuation towards end, the curves seem to reach stability after 150 days at a lower
level of yield compared to that of Figure 12
Figure 14 explains the median growth curve for different seed weights under three situations of yam detachments
viz., first interim cut, second interim cut, and undisturbed with no interim cut. The curve for second interim cut of
yam with seed weight 800 g seems superior.
Figure 14 Median growth curve for different seed weights
Note: Median growth curves in different scenarios are shown. If the fluctuations at the end of curves are ignored, seed weight 800 g
with cut at second interim reading time of four and half months after sprouting corresponds to the highest yield. Upturn in growth
curve corresponding to seed weight 500 g with cut at second interim reading time is also remarkable
Figure 15 explains the above scenario in terms of mean growth curve. The curve for second interim cut of yam
with seed weight 800 g is superior, if we incorporate the criterion of growth stability towards the far end of the
growth curves. In Figure 16, the assertion that the cut at the time of second interim growth recording of yam with
seed weight 800 g is superior becomes clearer from lowess regression of the curves with
f =
0.35
. Yam cut at
second interim growth recording with seed weight 800 g corresponds to higher yam yield. The corresponding
curve reaches a stable value of higher yield towards the end of plant lifetime viz., beyond 160 days.
Figures on growth curve indicate the following. For maximising the total yield, an interim detachment of yam
may be made during the season; but no further uprooting for interim records should be made to these plants till
maturity, as a downward slope of growth is then observed in general. Corm weight of 500 g is the minimal seed
weight for plant survival under the condition of nominal care of plants; some growth curves show no indication
of change over time, although downward slope of growth is arrested by uprooting and replanting plants after
interim growth record. Uprooting and replanting the plants during the experiment served as a favorable stimulus
for growth, when plant growth becomes inert under nominal plant care.
