How do apples get their shape? Plus, other traits.

When biting into a crisp, juicy apple, have you ever wondered how nature crafts these familiar fruits into their diverse and appealing shapes, flavors, textures, sizes, and colors? The growing process and development of apples is an intricate dance between genetics, environmental factors, and cultural practices. Let’s explore the fascinating journey of how apples acquire their uniqueness. Let’s begin our journey on how the parent trees determine the genetic foundation.

Parental Traits

The apple tree inherits traits from its parent trees, influencing the apples’ shape, size, color, flavor, and texture. For example, Honeycrisp’s exceptional sweetness, juiciness, texture, color, size, and shape result from crossbreeding Macoun and Honeygold apples. 

Macoun Apple

The Macoun apple is sweet and aromatic, with excellent eating qualities and a tender, crisp texture. The Macoun apple originated in the United States, specifically at the New York State Agricultural Experiment Station in Geneva, New York. Controlled breeding developed the variety, which the public learned about in 1923.

The Macoun apple name comes from Canadian horticulturist W.T. Macoun, an influential figure in the apple-breeding program at the time. It is a cross between the McIntosh and Jersey Black apple varieties. The goal of creating the Macoun was to produce an apple with the sweet and aromatic qualities of McIntosh and the firm texture of the Jersey Black.

Honeygold Apple

Honeygold apples are known for their distinct flavor profile, combining sweetness, tartness, and a hint of honey-like flavor. They are a cross between the Golden Delicious and Haralson apple varieties. The breeding work occurred at the University of Minnesota’s apple breeding program, which has been responsible for developing several apple varieties well-suited for northern climates. At Chelan Ranch, we grow our organic Honeycrisps in cold canyons at the 2000′ level, simulating northern climates. Our Honeycrisp trees thrive in this colder climate, and the fruit is outstanding with its crisp, sweet, and juicy flavor.

Genetic Foundations

The inheritance process represents the tie between parental traits and an apple’s genetic foundation. When an apple tree produces fruit, the genetic information in its DNA passes to the seeds within the fruit. This inheritance involves the transmission of genetic material from both parent trees, and it plays a fundamental role in shaping the traits of the resulting apple. So, the heart of an apple’s characteristics lies in its genetic blueprint.

How the Genetic Code Influences Flavor:

  • Sugar Content: The genetic code influences the apple’s sugar content by regulating the production of sugars during photosynthesis. Varieties with a higher sugar content are likely to have a sweeter flavor.
  • Acidity: Genes control the synthesis of organic acids in apples, such as malic acid. The balance of sugars and acids contributes to the overall taste profile. Some apple varieties, like Granny Smith, have higher acidity, resulting in a tart flavor.
  • Aromatic Compounds: The genetic code produces aromatic compounds, such as esters and aldehydes, contributing to the apple’s aroma. The presence and quantity of these compounds influence the perceived flavor.
  • Complexity of Flavors: Different apple varieties have distinct flavor profiles due to the combination of various compounds. For example, some apples may have floral notes, while others exhibit hints of spice or citrus.

How the Genetic Code Influences Texture:

  • Cell Structure: The genetic code dictates the arrangement and structure of cells in the apple, influencing its texture. Some apples have a more delicate and tender texture, while others are crisp and firm.
  • Pectin Levels: Genetics influence pectin levels, a structural polysaccharide in cell walls. Pectin contributes to the firmness and texture of apples. Varieties with higher pectin levels may have a crisper bite.
  • Water Content: Genetic factors influence the water content of apples, affecting their juiciness and mouthfeel. Some varieties are known for being exceptionally juicy due to their genetic makeup.
  • Starch to Sugar Conversion: Starches are converted into sugars as apples ripen. The genetic code determines the rate at which this conversion occurs, impacting the texture and sweetness of the fruit.
  • Enzymatic Activity: Enzymes play a role in the breakdown of cell walls during ripening. Genetic factors influence the activity of enzymes like polygalacturonase, affecting the apple’s softening and texture changes over time.

Line up of a variety of apples

The genetic makeup of an apple tree also carries the instructions for the fruit’s growth and development, including its shape. Different apple varieties have distinct natural shapes, ranging from round to oblong or asymmetrical, based on their genetic characteristics. Honeycrisp apples at Chelan Ranch Organics have a generally well-balanced and symmetrical shape. Our Sweetangos apples typically have a round or slightly conical shape. They are not excessively elongated or asymmetrical because of their genetic traits from the parentage of Honeycrisp and Zestar! 

The intricate dance of influence in developing an apple also involves environmental factors that play a significant role in shaping the physical characteristics of apples, including their size, color, and overall shape. Here are some ways in which environmental factors influence an apple’s shape.

Environmental Factors:

  • Pollination: At the fruit blossom stage of development, successful pollination is crucial for fruit development. The transfer of pollen from the male parts of a flower to the female parts initiates the formation of the fruit. At Chelan Ranch, we hire beekeepers to bring in bee hives that stay in the orchard for several weeks to assist with pollination. We also employ a helicopter to apply additional pollen as additional assistance.
  • Fertilization: Once pollination occurs, fertilization leads to the development of seeds within the apple. The presence, arrangement, and growth of seeds can influence the shape of the fruit. Often, when an apple is misshapen or lopsided, we’ll find it missing some seeds if we cut it in half crosswise.
  • Cell Division and Expansion: Cell division and expansion play a significant role as the fertilized flower develops into an apple. The arrangement and growth patterns of cells contribute to the overall shape of the fruit. During this stage, warm weather is ideal for larger-sized apples.
  • Position on the Tree: The apple’s position on the tree can also impact its shape. Apples that receive more sunlight and nutrients tend to develop more fully and uniformly. With winter and summer pruning, the intent is to open the tree to sunlight so all apples receive sunlight.
  • Environmental Conditions: Weather conditions, water availability, and soil quality can affect the growth of the apple. Adverse conditions may lead to irregularities in shape.

Right Plant, Right Place

When working with my master gardener volunteer group at plant clinic, a phrase frequently arises when clients struggle with a plant problem, “Right plant, right place.” The term “right plant, right place” is a gardening and landscaping principle that emphasizes the importance of selecting plants well-suited to the specific conditions of their intended growing environment. This principle applies to horticulture also. We can customize it to “right tree, right place.” 

An Apple Story

When growers saw the returns for Honeycrisp in the late 2000s, many only saw the dollar signs rather than the required growing conditions. If you’ve ever had a bad Honeycrisp of colossal size or pocked with bitter pit and a mushy texture with bland flavor, it probably came from an orchard in Washington’s low-elevation sunbelt. After growers spent extraordinary amounts of money on shade cloths and water cooling systems, most gave up trying to grow Honeycrisps. With the promise of an apple bred to endure Washington’s low-elevation hot environment, many growers switched their orchards to Cosmic Crisp. Cosmic Crisp is half Honeycrisp and half Enterprise. The Enterprise half brought characteristics that allow Cosmic Crisp to grow in low elevations with hot temperatures without damage, so growers wouldn’t need to spend excessive money on cultural practices such as shade cloth and water cooling systems.

Cultural Practices

Cultural practices, which include various orchard management techniques, can significantly influence the development of apples on the tree. These practices optimize growing conditions, enhance fruit quality, and manage pests and diseases.

Here are some ways in which cultural practices impact the development of apples:

  • Pruning: The cuts made pruning an apple tree can influence the distribution of energy and nutrients, potentially affecting fruit shape.
  • Thinning: Thinning of young fruit can help ensure that the remaining apples receive adequate nutrients, promoting a more uniform shape. We thin our crops early in the season, when the bloom is still on the tree, just after pollination with an organic spray of lime sulfur followed by hand thinning.

In our world of apple growing, the alchemy of flavor, texture, and appearance is a harmonious dance between nature and nurture. The genetic code embedded within each apple variety sets the stage, dictating the potential traits of the fruit. However, it is the interplay of growing conditions, climate nuances, and meticulous orchard management practices that transforms this genetic blueprint into the final masterpiece. From the embrace of sunlight and the gentle sway of the wind to pruning techniques and soil nutrition, every element leaves its imprint on the developing apples. The subtle art of balancing these environmental factors with the inherent genetic makeup and cultural practices is the daily challenge for us at Chelan Ranch. Each fall we hope for optimal results that are a rich tapestry of apple varieties to savor – each with its own unique characteristics, a testament to the marriage of nature’s code and the hands that nurture it in our orchards at Chelan Ranch.

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