International Journal of Horticulture, 2017,Vol.7, No. 23, 205-218
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yam yield from these could be much higher, although 500 g is the least seed weight considered in the experiment.
3.3 Three dimensional figures on proliferation rates
Three dimensional figures provide a deeper insight into the yam growth process compared to 2-dimensional plots,
on variation of rates with simultaneous variation in two auxiliary variables associated with yield on continuous
scale.
In Figure 11 proliferation rates of yield vs. time and seed weight are shown. This picture is based on raw data
collected, enabling comparison with two dimensional Figure 8, Figure 9, and Figure 10. Seed weight 500 g has
highest value on the surface of proliferation rate. The other peak of the curve at far end, corresponding to the seed
weight 800 g is in a slanted surface downward, these seed weights correspond to lower values of peaks in
proliferation surface. For all other seed weights the peaks of the rates are attained inside the time range. Seed
weight 500 g has highest value of proliferation rate in Figure 10. The same is expected to be seen on the surface
of proliferation rate in Figure 11.
In Figure 12 proliferation rates of yield vs. time and plant height are shown. The figure reveals that high value of
proliferation occurs at about 120 days for plants of average height. If the plant height is high in less time, then the
rate is high. The same is true, if plant height is moderate at large value of time.
In Figure 13 proliferation rates of yield vs. time and canopy radius are shown. High values of proliferation occur
for moderate value of canopy radius. For canopy radius around 40 cm, rate is usually high after a time lapse from
sprouting. For large values of canopy radius, proliferation rate attains high values relatively early.
For plants with fixed seed weight undergoing second interim cut, we computed the coefficient of variation (c.v.)
for the stem perimeters: maximum girth at base, maximum girth at middle, maximum girth at top of stems;
maximum is also taken over lifetime of plants. It turned out that c.v. of `maximum girth at top' are the highest
amongst recordings of girths on base, middle and top of stem, within each group of seed weight 500 g, 650 g, 800
g; the highest values of c.v. in the respective groups are 16.79542104, 12.58080459, 15.77286043. All these
correspond to the girth at top of stems in plants, indicating maximum variation of girth at stem top, in collected
data for analysis. Consequently, out of measures on girth at three locations, we shall consider girth at the top of
stem to draw 3 - dimensional picture to study variation of proliferation rate with respect to girth.
In Figure 14 proliferation rates of yield vs. time & maximum girth at top of stem are shown. Proliferation rate is
high in general, when girth is around 6 cm. In the middle of lifetime, if the girth is approximately 5 cm then the
rate is high. The upper edge of proliferation surface corresponds to around 120 days.
When seed weights are not recorded, Figure 12, Figure 13, and Figure 14 may shed light on the plant growth
status on yield.
Figure 11 Proliferation rate of yield vs. time & seed weight: 2nd interim cut
