Requirements for early maturity may include:
- Early canopy senescence and skin set
- Large tubers early in the season
- High dry matters early in the season
- Low sugars early in the season
Early canopy senescence and skin set
- Use a suitable cultivar – it will always be difficult to achieve early maturity of a late-maturing cultivar such as “Cara”.
- Physiological ageing of seed should have some influence but cannot be expected to turn a late-maturing cultivar into an early one.
- Avoid excess or late nitrogen application: remember that restricting nitrogen will restrict the rate of tuber bulking.
- Canopy destruction may be practised e.g.:
- mechanical destruction (flailing etc)
- however the more immature a canopy, the more difficult it is to kill. Affects on tuber dry matter should also be considered.
- Withholding irrigation can result in early canopy senescence; affects on tuber yield and dry matter should also be considered.
- Conclusion: early canopy senescence may be encouraged by
- choice of a suitable cultivar,
- advancing growth,
- withholding nutrients and irrigation,
- use of desiccants.
More information on senescence.
More information on skin set.
Large tubers early in the season
- A relatively low number of tubers will be required.
- All constraints should be eliminated to ensure that individual tubers grow at a fast rate.
- Ensure an adequate supply of water, nutrients and carbohydrates.
- Avoid damage by pests and diseases.
- An early onset to growth is necessary but early planting is unlikely to result in a fast rate of growth.
- Physiological ageing of seed may provide an early onset to growth.
- Covering the rows with polythene may provide an early onset to growth if the soil temperature is increased.
- Conclusion: large tubers may be achieved early in the season by:
- a low number of tubers,
- individual tubers growing at a fast rate,
- an early onset to growth.
High dry matters early in the season
- Tuber dry matter concentration is strongly influenced by:
- tuber size
- availability of water
- but is less strongly influenced by nutrition.
- Physiological ageing of seed may result in a high tuber dry matter concentration early in the season – if ageing results in an early onset of growth.
- Covering the rows with polythene may have a similar effect to physiological ageing of seed.
- Restricted availability of water can result in high dry matter concentrations, however tuber yield and mean tuber size will also be restricted.
- Withholding water can alter the relationship between mean tuber size and dry matter concentration.
- Nutrition for high dry matters:
- Avoid excess nitrogen (use the PRG nitrogen rate).
- Avoid late application of nitrogen (do not apply after the onset of tuber bulking unless to replace leached nitrogen – see the PRG Nitrogen Model).
- Avoid excess potassium (use the PRG Potassium rate).
- Avoid any nutrient deficiencies which could restrict the rate of tuber growth.
- Conclusion: high dry matter early in the season requires:
- a suitable cultivar,
- an early onset of growth,
- large tubers,
- appropriate nutrition,
- restricted availability of water.
More information on dry matter concentration.
Low sugars early in the season
- Concentration of sugars differs between cultivars.
- Concentrations of sucrose and reducing sugars are related to tuber size – the larger the tuber, the lower the concentration of sugar.
- Concentration of sugars may be increased by stress e.g. cold, drought.
- Conclusion: low sugars early in the season require:
- a suitable cultivar,
- an early onset of growth (see Large tubers),
- large tubers,
- avoidance of stress.
More information on sugars.
Notes on early maturity
Early dates of crop production 2011 (Use of crop covers to advance early development)
Achieving early maturity 2000 (Includes senescence, tuber size and dry matter concentration)