Effects of plastic film covers on dry‐matter production and early tuber yield in potato crops

Abstract

SummaryThree experiments, conducted in 1988, 1989 and 1990, examined the effects of date of removal of a clear, perforated (200 X 10 mm holes m‐2), plastic film cover on the growth and early yield of potato crops. Results confirmed that the highest early yields were achieved when the cover was removed 2 wk after 50% crop emergence and the resulting yield increase over a non‐covered control varied from 6–14 t ha‐1. Later removal reduced the benefit from covering and in some cases eliminated any advantage. Covering increased mean soil and air temperatures 2.9°C and 3.2°C respectively (mean of three experiments), thereadvancing crop emergence between 3 and 5 days. The number of day‐degrem accumulated between planting and emergence was very similar in covered and non‐covered treatments within a season but varied between seasons from 190°C to 293°C day (> 0°C). Delaying removal resulted in an increased physical restriction to canopy expansion and reduced the capacity of the crop to intercept solar radiation. Total dry‐matter yield was determined largely the amount of radiation intercepted crops (R2= 0.98). Plastic covering had relatively little effect on partitioning of dry matter to tubers but reduced tuber dry‐matter percentage at early harvests when removal occurred later than 3 wk after crop emergence.