The effect of mineral nutrition on the biochemical composition of pome and berry crops

How mineral nutrition affects sugar accumulation in fruits

The flavor and market quality of fruit and berry crops directly depend on their sugar content, the accumulation of which is determined by the balance of mineral nutrition. A deficiency of any nutrient element impairs plant growth and reduces photosynthetic activity. As a result, sugar concentration decreases and the flavor qualities of the harvest deteriorate.

The carbohydrate composition of fruits changes as they develop. In the early stages, structural carbohydrates are primarily formed — pectins, hemicelluloses, and cellulose, while in apples, pears, and bananas, starch accumulates. During ripening, the conversion of polysaccharides into sugars is activated. In berries, little sucrose is synthesized, and their carbohydrate profile is represented mainly by glucose and fructose. In pome fruits, fructose prevails, whereas in stone fruits, it is glucose.

• Average sugar content in fruits — 6–12 %
• In lemons — 1–3 %
• In strawberries — 12–20 %
• In grapes — 20–26 %

For maximum sugar accumulation, balanced application of macro- and micronutrient fertilizers is required. This saturates the photosynthetic apparatus with plastid pigments and increases the intensity of photosynthesis. Leaves begin to actively produce assimilates, which are transported to fruits and berries, stimulating sugar accumulation.

Lipids in plants and oil content in crops

Lipids are one of the four key classes of organic compounds in living plant tissues, along with carbohydrates, proteins, and nucleic acids. They represent a diverse group of substances that are insoluble in water but soluble in non-polar solvents (diethyl and petroleum ethers, benzene, chloroform, carbon disulfide). This class includes:

• fats and waxes;
• steroids;
• phospholipids;
• glycolipids and sulfolipids;
• cerebrosides.

In the vegetative parts of plants, lipid concentration is low and usually accounts for less than 1 % of the total dry mass. Their main accumulation occurs in seeds and fruits. Here they are deposited in the form of oils and fats, representing the greatest value for the food industry.

Most oil crops have an ancient history of cultivation. For example, in East Asia, soy and hemp were grown as early as the III and VIII millennia BC, respectively, although soy appeared in the territory of modern Russia only at the end of the XIX century. Sesame was cultivated in Asia and Africa 4,000 years BC; detailed cultivation techniques were described in works from 300 BC, and the use of sesame oil is mentioned in sources from the I century AD. Cotton has been cultivated since ancient times in India, Peru, Mexico, and Iran.

Findings of opium poppy date back to Neolithic agriculture, to the life of stilt-house dwellers. The oldest center for cultivating Sarepta mustard was Ancient China, from where it spread to India. Safflower has been used by the peoples of Asia and Africa since ancient times. The peanut originates from South America and is cultivated in all countries of the tropical and subtropical belts of the globe. The inclusion of sunflower in the range of plants cultivated by humans in its homeland, America, occurred in pre-Columbian times. The olive should also be considered the most ancient oil crop of the Mediterranean countries.