How Fertilizers Affect The Quality Of The Crop - 3

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

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Alkaloids are heterocyclic nitrogen-containing substances of an alkaline nature with a strong physiological effect. They are synthesized in significant quantities and accumulate in certain groups of agricultural plants. The alkaloid nicotine (3-7%) accumulates in the leaves of tobacco, which is used for smoking, in the leaves of lupine - lupinine, sparteine, lupanine and some other alkaloids (1-3%), which are toxic to humans and animals, in animal feeding, alkaloid-free lupins, in the bark of the cinchona tree - the alkaloid quinine (8-12%), which is used for medical purposes, in the poppy - opium, morphine, narcotine and codeine - are used in medicine.

The alkaloid caffeine is found in coffee beans (1-3%), in tea leaves (up to 5%), in small amounts in cocoa beans, cola nuts and other plants. Alkaloids are widely used for medicinal purposes. When applying fertilizers, the content of all the considered biochemical compounds cannot be increased at once. This is not necessary. However, the content of this or that substance can be planned and increased with the help of fertilizers. The mechanism of action of fertilizers on the chemical composition of plants and the quality of the crop depends on the course of two oppositely directed processes occurring in plants. On the one hand, this is the biosynthesis of proteins and other nitrogenous compounds, and on the other, the biosynthesis of carbohydrates or fats. Both processes require different conditions. Almost always, when the process of protein biosynthesis is enhanced, the accumulation of carbohydrates or fats decreases, and vice versa.

Fertilizer nitrogen entering plants is quickly converted into amino acids already in the roots, from which proteins, nucleic acids, chlorophyll, vitamins, alkaloids and other compounds are then synthesized. Therefore, better conditions for nitrogen nutrition contribute to a more intensive accumulation of these compounds in plants. With a lack of nitrogen, the content of proteins and especially non-protein nitrogenous compounds in plants is significantly reduced. The relative content of starch and sugars is higher. However, a sharp nitrogen deficiency can cause a decrease in the content of mobile forms of carbohydrates due to an increase in fiber and other insoluble forms of carbohydrates. With the introduction of nitrogen fertilizers, the content of "crude protein" increases, while the content of carbohydrates decreases.

This decrease is explained by the fact that at many stages of nitrogen metabolism (during the reduction of nitrates to ammonia, the biosynthesis of amino acids from ammonia, the biosynthesis of amides, nitrogenous bases, nucleic acids, proteins and other compounds) the plant spends a lot of energy, which is obtained mainly due to the consumption of carbohydrates in the process of their oxidation. The carbon skeleton of the resulting nitrogenous compounds is also built at the expense of carbohydrates or their conversion products, as a result of which, with enhanced nitrogen nutrition, a significant part of the carbohydrates fixed during photosynthesis is spent on the biosynthesis of nitrogenous compounds. Thus, with increased nitrogen nutrition, the content of carbohydrates or fats in plants decreases.

To improve the quality of agricultural crops, the forms of nitrogen fertilizers used are also important. In particular, with ammonia nutrition of plants, the metabolism shifts towards the accumulation of a larger amount of reduced compounds (essential oils, alkaloids), and with a nitrate source of nitrogen, the formation of oxidized compounds, mainly organic acids, increases. Phosphorus has a very strong influence on many biochemical processes in plants, which is directly involved in the synthesis and decomposition of sucrose, starch, proteins, fats and many other compounds. Therefore, under the influence of phosphorus fertilizers, the intensity of their synthesis is sharply increased. The intensity of protein synthesis under the influence of phosphorus also increases, but to a lesser extent than the accumulation of sucrose or starch. Therefore, as a rule,with a lack of phosphorus, plants contain a relatively smaller amount of sucrose and starch compared to the content of proteins, and with the introduction of phosphorus, the intensity of carbohydrate synthesis increases.

To obtain a high-quality harvest, not only the absolute level of supply of plants with certain nutrients is important, but also the ratio between individual elements, mainly between nitrogen and phosphorus, nitrogen and potassium, N, P, K and trace elements. By changing their ratio, one can noticeably regulate the intensity and direction of metabolic processes and cause the greatest accumulation of proteins or carbohydrates. Potassium has a positive effect on the rate of photosynthesis and on the biosynthesis of sucrose, starch and fats in plants. Protein biosynthesis with the introduction of optimal doses of potassium fertilizers is also enhanced. When comparing various sources of nitrogen (ammonia or nitrate), the positive effect of potassium on protein synthesis with ammonia nutrition is especially noticeable. Insufficient plant nutrition with potassium leads to a weakening of the synthesis of sucrose,starch and fats, which leads to an increase in the content of monosaccharides.

The most important chemical compounds, for the sake of which many plants are grown, are sucrose and monosaccharides. The nutritional value of many vegetables is determined, first of all, by their sugar content. Therefore, when growing vegetables and fruit and berry crops, it is necessary to create conditions under which the greatest amount of sugars accumulates. Each kilogram of the active substance of phosphorus and potassium fertilizers provides an increase in sugar collection by 10.5-17.5 kg, these fertilizers have the greatest positive effect on the sugar content of products. In addition, under the influence of these fertilizers, the content of a number of vitamins also increases.

The problem of improving the quality of the crop and the content of fat in it, especially in sea buckthorn berries, seeds of pumpkin crops, sunflowers and other oilseeds, is extremely important. Fats in plants are formed from carbohydrates, so there is an inverse relationship between the protein and fat content: with the highest fat content, the amount of protein in the seeds decreases, and vice versa. Therefore, in order to increase the fat content in the seeds, it is necessary to promote the accumulation of carbohydrates and, therefore, to increase the synthesis of fats in the seeds and to reduce the protein content. Phosphorus and potash fertilizers have the greatest positive effect on increasing the oil content of seeds. When these fertilizers are applied, the fat content in the seeds increases by 2-4%. Nitrogen fertilizers increase the intensity of protein synthesis,as a result, the protein content in the seeds increases, and the fat content decreases.

Therefore, nitrogen has a negative effect on the accumulation of fat in the seeds, while phosphorus and potassium have a positive effect. With local application of fertilizers for agricultural crops, the payment for a unit of fertilizer increases significantly. Local application of phosphorus fertilizers during sowing has the greatest positive effect on the yield and fat content in seeds. With the local application of 10 g of superphosphate, the fat content in the seeds increased by more than 4%. Nitrogen fertilizers, when applied locally, have a negative effect on the yield and the fat content in the seeds, and under the influence of potassium, the amount of fat increases significantly.

Along with a change in the content of fat in seeds under the influence of fertilizers, there is a change in the qualitative composition of fat, the amount of unsaturated fatty acids increases. Phosphate and potash fertilizers most strongly increase the content of unsaturated fatty acids in the oil. In addition, the technical value of the fat increases, this fat dries more easily, and from it a drying oil and varnish of better quality are obtained.

Nitrogen fertilizers have a significant effect on the quality of fat, when the content of saturated fatty acids in the oil increases, and the content of unsaturated acids decreases. In accordance with this, the iodine number of the oil decreases under the action of nitrogen. Thus, the conditions causing a decrease in the fat content also lead to a deterioration in its quality, and with a higher fat content in the seeds, its quality, as a rule, increases. Under the influence of fertilizers, the content of many other substances in the crop changes - vitamins, essential oils, alkaloids, organic acids, mineral salts, microelements. With the correct application of fertilizers (optimal doses and timing of application, the correct combination of different forms of fertilizers, harvesting 30 days after fertilization, etc.), the content of these valuable substances in the crop can also be positively increased. T

Thus, depending on the conditions of mineral nutrition, the chemical composition of plants and the quality of the crop can undergo significant changes. Here you need to keep in mind not only the content of protein, carbohydrates, fat, solids, phosphorus, potassium, trace elements necessary for human nutrition, but also the color, size of fruits, the yield of commercial products of the first or second grade, keeping quality, taste, smell, suitability for canning and other quality indicators specific to individual crops or plant cultivation purposes. We'll talk about them later.

We hope that gardeners and vegetable growers will find useful advice on crop quality management. We wish you success!