How crop nutrition affects apples

Balanced nutrition is needed to achieve high yields. High yields are a function of fruit number and fruit size. To obtain high apple yields it is important to achieve the right balance of fruit numbers on the tree.

Fruit number in apple trees results from a variety of factors, including planting density, orchard system, pruning and thinning practices and also crop nutrition.

Apples size is influenced crop nutrition together with pruning and thinning practices. Size is a critical characteristic for grading apples. A minimal size is required on all grades and evenly shaped and sized fruit are desired for all markets.

Crop nutrition plays an important role on increasing apple weight. Apple weight is an important element for increasing yields. Provided that a desired quality is maintained, the aim of growers is to produce heavier fruits.

Colour of the skin is a very appealing apple quality to consumers. Therefore, growers generally seek to improve fruit colouration. Crop nutrition can help to achieve the desired appearance.

Nutrition can influence apple firmness. Nitrogen, potassium and calcium are the most important nutrients.

The sugar/acidity ratio of fruit is what gives fruits characteristic taste and flavour. Balanced crop nutrition programmes help growers manage an acceptable TSS/Acidity balance in the fruit.

A balanced crop nutrition is essential for the management of bitter pit. Bitter pit is a physiological disorder associated with low levels of calcium in the apple tissue, which reduces apple quality and marketability.

Lenticel blotch is associated with excessive use of nitrogen, hot summers and late harvests. Lenticels are slightly sunken blotches that result in underlying tissue drying out and becoming brown and spongy.

Inadequate supply of calcium is a major contributing factor to water core. Watercore develops in mature apples when the sugar sorbitol is translocated into the fruit faster than it can be assimilated.

A good crop nutrition can help to minimize internal breakdown incidence in apples. It can be associated with intense water core disorder, cold storage, and boron and phosphorus deficiencies.

Sunscald or sunburn in apples accounts for yellow or flushed areas on the fruit skin due to direct sun damage often following a period of cooler, cloudy weather. It is often associated with poor calcium content in the fruit. A balanced crop nutrition can help avoid sunburns.

Many disease-causing pathogens attack apple trees often leading to rotten fruit and storage rots. A balanced crop nutrition programme leads to a more robust, healthier tree more able to resist infection.

Calcium is critical in pears, and fruit concentrations need to be double that acceptable for apple.

Alfalfa greening is a disorder which causes dark-green, slightly sunken spots on the skin of pears. A balanced crop nutrition is essential to minimize alfalfa greening occurrence.

Yara's apple fertiliser recommendations and crop nutrition programmes can help you to achieve excellent growth and maximise the yield and quality of apples.

Most nutrients are stored and retained as reserves in tree buds, bark and roots. These are then remobilized after winter to fuel leaf growth, flower bloom, fruit formation and growth.

Apple nutrient requirements vary depending on the crop growth stage. Find out which nutrients are most important at different growth stages.

The aim of every apple grower is a high yield of top quality fruit and there are a large number of agronomic factors which can influence this, many of which are within their control given their specific growing systems and climatic/soil conditions.

The majority of apples are grown for the fresh market. Retailers and consumers are demanding increasingly higher quality fruit, right throughout the year. Processors also seek good quality fruit although they are more tolerant of appearance, .

Leaf tissue analysis is commonly used to provide a snapshot of nutrient status at specific stages of growth. Typical leaf analysis figures for optimum growth for both macro and micronutrients are used to develop crop nutrition recommendations.

Apples and pear trees can grow in a wide range of soils from medium textured clays to gravelly sands.

Various nutrient applications strategies should be adopted in apple and pear orchards to ensure the right amount of each nutrient is available to the tree when required and in a form that is readily available.

There are many different varieties of apples and pears. Apples are the most important pome fruits grown in temperate regions with most being grown for fresh fruit

Nitrogen has a major effect on yield and quality. It is a component of the chlorophyll molecule and involved in nucleic acid synthesis and hence important for cell division and the growth of young tissues.

Potassium promotes strong vigorous tree growth, boosts fruit size and cell strength. It also encourages good tolerance to pests and diseases

Calcium activates enzymes and is essential for cell division, elongation, and fruit growth. It stabilizes and ensures permeability of the cell wall, protecting it from degradation by enzymes.

Magnesium is a key constituent of the chlorophyll molecule; usually 15-20% of the tree’s Mg total is found in the chloroplast. It is also involved in various biochemical functions including activating enzymes involving phosphorylation, and protein synthesis.

Sulphur is a key component of amino acids, proteins and coenzymes. Thus, lack of sulfur will inhibit protein synthesis and reduce tree growth.

Boron is involved in cell wall formation, stabilisation and lignification, and xylem differentiation. It is needed to ensure normal development of new tissues from roots to flowers and fruit.

Copper is required for chlorophyll synthesis and is a constituent of enzymes responsible for the reduction of molecular oxygen.

Iron is required as a precursor to chlorophyll formation and in a number of important plant enzymes. Poor supply restricts photosynthesis and, as a result, reduces leaf growth and resultant fruit yield and quality.

Manganese is involved in a wide range of enzyme processes including hormone synthesis. It also plays a key role in photosynthesis.

Zinc functions in many enzyme systems and biochemical functions including acting as a precursor of indoleacetic acid which is involved in shoot elongation. The micronutrient thus plays a major part in bud development and flowering.