Longitudinal growth curve of elephant foot yam under extreme stress and plant sensitivity II

Document Type

Conference Article

Publication Title

Springer Proceedings in Mathematics and Statistics


Plant sensitivity under extreme stress and minimal survival environment for yam plants are examined. In order to maximise total yam yield, Dasgupta (2017a) studied longitudinal growths of 60 Elephant-foot-yam, 20 for each seed weight 500, 650 and 800 g with option of interim yam detachment in either of the two time points, along with final harvest on maturity from replanting the stems, in a field experiment conducted in an agricultural farm at Indian Statistical Institute, Giridih, Jharkhand (India) during the year 2016–2017. Detaching yam around four and half month from sprouting for plants with seed weight 800 g, and replanting the remaining stem structure with some roots attached to it and continue experiment till final harvest on maturity, was seen to have significantly increasing effect in two stage harvest, in an agro-climatic environment with minimal survival condition for yam plants. In the experiment conducted, only a few irrigations were given in the peak summer temperature and little manure was administered in the start of the experiment. We now construct almost sure bands of growth curves based on the data from above mentioned experiment. These indicate that the curves are distinct, and yield for seed weight 800 g is superior from other seed weights under the induced extreme plant stress. Proliferation rates of yam yield with seed weight 500 g stops above zero towards end, indicating possibility of further growth of yam, if plant lifetime could be extended. In the case of extreme plant stress under yam detachment at the time of second interim reading, we look for a ‘50 day window’ from sprouting in which the accumulation of underground yam is high i.e., area under the proliferation rate curve is high, to identify the time region of high yam growth. This turns out to be the time span [50, 100] days for seed weight 800 g. For other seed weights 650 and 500 g, the time span is [100, 150] days. From the peaks of proliferation rate curves, it appears that yam deposition rate for seed weight 500 g is about three times compared to those with seed weight 650 and 800 g, in the ‘50 day window’ time span of high deposition. Individual growth trajectories are modeled by a correlated Gaussian process. Test of hypothesis on parameters of the modeled process indicates the possibility of error components following a Brownian motion.

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