Relation of elevation to potato growth and propagule productivity

Abstract

To document the effects of the high altitude environment on the growth and development of the potato (S. tuberosum), plants of cv. Kennebec were grown at sites ranging from 1533 to 3213 m. Temperature and light were the environmental parameters of primary interest and the experiment was designed to eliminate other influences. Since insolation was high at all sites, shade structures were installed to provide a wider range for this factor. Maximum vegetative growth occurred at 2372 m. This site had a mean temperature of 17° C with a wide diurnal range. Above 2800 m, unshaded leaves exhibited a pronounced folding considered to be a response to high light intensity. Tuber fresh weight per plant decreased only slightly with increasing elevation. Shading increased vegetative growth and reduced tuber yield and specific gravity at all elevations. Shading also retarded maturity as evidenced by the consistently higher nitrate content of leaves from shaded plants. Regression analysis indicated that maturity, as measured by tuber specific gravity, was highly correlated with accumulated heat input. Net assimilation and tuber yield were positively correlated with total insolation and a revised measure of heat input designed to compensate for increasing respiratory losses with increasing night temperature. A comparison of site potential is presented. Tubers produced at the various sites were grown in a greenhouse under controlled conditions to determine the effect of the parents' environment on the yield potential of the succeeding generation. Rate of emergence of the progeny increased with increasing elevation of the parent. This earlier emergence was reflected in earlier vegetative growth and tuber initiation which resulted in higher tuber yield early in the season. However, when grown to completion, there was no significant difference in vegetative growth or tuber yield among groups. Photosynthetic rates were determined. The environment of the parent had no influence on the photosynthetic activity of the progeny.