High field crop yields are obtained on freely drained soils where water and nutrients are not limiting. Plant density and spacing are critical to ensure crops make best use of environmental, especially light conditions, so that yield potentials are reached.
Maintenance of optimum soil pH ensures nutrients are readily available. The use of herbicides or cultivation will remove any weed competition.
Temperature and light intensity are critical at flowering to ensure unhindered flower formation, good pollination, fertilization and fruit set.
High temperature stress can lead to bud abscission prior to flowering. The same conditions at flowering will lead to abnormal flower development and death.
Growers can minimize the competitive effects of excessive vegetative development by leaf pruning – most commonly by removing the lower leaves to allow more light to reach the ripening fruit. This also provides better air movement around the lower stem, reducing the impact of stem diseases. It is important to avoid excessive leaf pruning in high light environments as the crops can be at risk of sunscald.
Maintaining a leaf area index of 3 will maximize fruit growth. Hand thinning of tomatoes on the end of a truss ensures more evenly sized, larger fruit.
The use of growth regulators such as auxins at anthesis can stimulate fruit set, and increase fruit size especially under low light and low temperature conditions.
Carbon dioxide enrichment in greenhouse crops increases individual fruit weight and total yield. This is especially true in greenhouses with limited ventilation.
The control of salinity by good leaching practices within the root environment and water supply management will maximize growth and ensure good nutrient availability.
Crop nutrition is essential
- Nitrogen and potassium are fundamental to achieving high marketable yields. Correct form of nitrogen is critical – ammonium can restrict growth and adversely affect quality.
- Phosphorus is important for early growth and root development of the establishing seedling.
- Calcium is needed to ensure vigorous leaf and root development and canopy growth.
- Magnesium is particularly important at flowering and then throughout fruiting to ensure good flower set and fruit fill.
- Unavailability of any micronutrient will restrict yield.
