International Journal of Horticulture, 2017, Vol.7, No. 12, 95-105
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Figure 15 Mean growth curve for different seed weights
Note: Mean growth curves in different scenarios reveal the same pattern as that of median curves. Yam detachment at second interim
reading time of four and half months after sprouting with seed weight 800 g seems to be the best strategy for high total yam yield
Figure 16 Lowess growth curve (mean) for different seed weights
Note: Lowess regression with
f=
0.35 on mean growth curves in different scenarios to smooth local irregularities reveals that second
interim cut for 800 g of seed weight produces high yam yield. However, first interim cut for the same seed weight is also of good
performance towards beginning, it loses superiority due to uprooting at the time of second interim growth recording. Upturn in
growth curve from a low value corresponding to seed weight 500 g with cut at second interim reading time is remarkable, the
growth curve in deep blue is convex; with sharp upturn compared to all other curves after five months
3.3 Sensitivity of plants under stress, affecting yam production in a positive manner
Curves with interim of yam detachment show an upper trend, indicating plants’ alertness to counter the extreme
stress by gathering resources for subsequent higher growth. Even when the plants are just uprooted and replanted
without detachment of underground yam, the plants are subjected to stress to an extent, and this helps the plants
to come out of inert state of growth as seen in reverting from the downward trend in curves, and then the curves
turn towards a favorable change in growth slope showing improved status.
4 Discussions
In the present investigation we see that a two stage harvest of yam with first harvest at about four and half month
from sprouting produces significantly higher yield. Study methods practiced a procedure on application of growth
curve analysis. With extreme plant stress, higher seed weight 800 g comes to the forefront of yam yield scenario
surpassing the seed weight 650 g of the previous experiments. With interim yam detachment around four and half
month after sprouting; plants with higher seed weight 800 g can achieve higher total yield in a harsh
agro-climatic environment and are able to cope with extreme plant stress for survival and growth.
