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Increasing Strawberry Fruit Number

Potassium has a direct effect on flower number and consequent fruit set (Figure 44). High levels of potassium – 3.5-4.5kg K/t of fruit - are required for strong crop growth. Compared to other nutrients (e.g. nitrogen), potassium is hardly diluted in the fruit during ripening, so supplies need to be maintained throughout maturity as the fruit changes color (Figure 45). Peak uptake is between fruit formation until the end of harvest.

Graph 45 - Nutrient Concentration Change During Ripening

Graph 46 - Potassium – Yield and Fruit Weight

As a consequence of good K supply, fruit weight and yield is increased (Figure 46).

Boron

A good supply of boron is important for root growth, pollen germination, seed formation and fruit set. Boron also has a direct effect on membrane integrity, maintaining cell wall structure.

Typical requirements are around 5g/t of fruit (Figure 20). Uptake increases during flowering and leads to good accumulation in the fruit. The B requirement varies between varieties and this needs to be taken into account when devising nutrient programs. Trials show a clear benefit from boron in terms of fruit set, fruit number and fruit weight, leading to improved yields (Figures 76 to 78). This may in part be due to boron’s influence on pollen formation and better pollination.

Graph 78 - Foliar B and Ca - Yield and Quality

Zinc

Applications of zinc can increase fruit numbers per plant leading to higher yields. But too much zinc leads to fruit deformation (Figure 91).

Zinc is found in relatively high quantities in the flowers and fruits compared to other micronutrients. Over 30% of all zinc is contained in the fruit (Figure 21) and 2.5g/t is taken up by the plant to produce 1 ton of fruit (Figure 20).

Zn deficiency usually occurs at leaf contents below 10-20ppm Zn. Too much zinc - at leaf concentrations above 50ppm – results in toxicity (Table 9). Deficiency problems are worse on high pH soils (>pH 7.0) and exacerbated in highly or recently limed soils. When insufficient zinc is available, foliar zinc can help increase yield.

Recommended Yara Fertilizers for Soft Fruit

YaraLiva CALCINIT

15.5% N + 18.8% Ca - Fully water soluble nitrogen and calcium fertilizer which is a free flowing and dissolves quickly in water without any residues so is suitable for application through all fertigation systems.

YaraTera KRISTALON SCARLET

7.5-12-36 + 4.5% MgO 10% SO₃ - A water soluble NPK fertilizer for liquid feeding and contains a full range of chelated micronutrients ideal for all fertigation systems.

YaraTera KRISTALON RED

12-12-36 + 1% MgO 2.5% SO₃ - A water soluble NPK fertilizer for liquid feeding and contains a full range of chelated micronutrients ideal for all fertigation systems.

YaraTera KRISTALON LILAC LB

20-8-8 + 2% MgO 25% SO₃ - A water soluble NPK fertilizer for liquid feeding and contains a full range of chelated micronutrients ideal for all fertigation systems.

YaraTera KRISTA K PLUS

YaraTera KRISTA K PLUS 13.7% N 46.3% P₂O₅ - A fully water soluble nitrogen and magnesium fertilizer. It is a free flowing fine crystalline powder which dissolves quickly in water without any residues.

YaraTera KRISTA MAG

YaraTera KRISTA MAG - 11% N 15% MgO - A fully water soluble nitrogen and magnesium fertilizer. It is a free flowing fine crystalline powder which dissolves quickly in water without any residues.

YaraTera REXOLIN Q15

YaraTera Rexolin Q15 is a high performance microgranular EDDHA iron chelate containing 7% iron with 1.5% of the iron as the ortho-ortho isomer. The micro granular formulation is stable, fully water-soluble and non-dusting. Ideal for use in agriculture and horticulture in soil applications. The product is specifically formulated to provide maximum crop safety. This helps to ensure that application will not cause damage to the crop which can reduce it's market value. Analysis 7% w/w = 70 g/kg Fe (chelated by EDDHA) Pack Size 25kg Available in England and Wales, Scotland and Northern Ireland..