Potato performance in response to different mulches. I. Nitrogen metabolism and yield

This work evaluates the impact that the application of different mulches ex erts on nitrogen (N) metabolism in roots and leaves and on yield of potato tubers (Solanum tuberosum var. Spunta). The parameters analyzed in this exp eriment were root temperature; nitrate reductse and nitrite reductase activ ities; concentrations of nitrates, ammonium, amino acids, proteins, and org anic N; dry weight of roots and leaves; and tuber yield. Use of white polye thylene (T2) and white-black plastic (T3) promoted optimal root temperature s for plant growth (23-27 degrees C). Under these experimental conditions, plants showed the greatest efficiency in N utilization and the greatest yie ld in tubers. Considering the sensitivity of this plant to thermal stress, high root temperatures caused by black polyethylene (>31 degrees C) (T4) de pressed N metabolism as well as yield, compared with the results of T2 and T3. Finally, clear polyethylene plastic (T1) caused more damage than did th e absence of mulch (control, T0).