Potato ( Solanum spp.) in an isohyperthermic environment. I. Agronomic management

Abstract

The agronomic management of the potato was studied to explore the potential for growing potatoes in an isohyperthermic environment. Twelve experiments were conducted from November 1983 to March 1986 on a clay loam Typic Argiustoll at 150 m a.s.l. at 14°N latitude in The Philippines. Mean minimum air temperature ranged from 22°C in late November and in March to 20°C in January. Mean maximum temperatures ranged from 27 to 30°C. Larger-sized seed gave superior tuber yields averaging over 21 t ha −1 for the best treatments in five experiments. Highland seed constantly produced superior yields primarily because of better plant survival. All three cultivars evaluated in this respect (Sequoia, Desiree and LT-5) had similar responses to seed size. Desprouting did not improve yields of well-sprouted highland seed. Seed rates from 1.5 to 2.5 t ha −1 gave similar yields regardless of seed size from 20 to 50 mm diameter. Seed rates of 1.0 and 3.0 t ha −1 significantly reduced and increased yields, respectively. Increased plant densities of up to 80 000 plants ha −1 improved tuber yields. This coincided with a stem ha −1 population of over 200 000. The most important factor in obtaining maximum yields was canopy duration. In five experiments, yield = −1.98 + 0.05 x canopy duration with R 2 = 0.67. Increased branching provided good canopy development at lower plant populations. Double-row beds enhanced yields by up to 3 t ha −1 over single-row ridges. Shallow planting gave faster emergence and canopy development but it did not improve yields. It resulted in more tuber greening. Hilling reduced greening at shallow planting. Results of the twelve experiments show the possibility of producing potatoes in an isohyperthermic environment. With optimum agronomic practices, yields of over 20 t ha −1 can be obtained with cultivars such as Cosima.