Plant life factors are the environmental conditions necessary for plant growth and development.
Plant life factors include light, air, water, heat, and nutrients. An optimum ratio of these factors can fully meet the needs of plants, which ensures good growth, development and fruiting. If the conditions do not meet the needs of the plants, this can lead to stunted growth and death.
Plant life factors are divided into:
- terrestrial, that is, derived from the soil and atmosphere – water, air, nutrients;
- cosmic, that is obtained by solar energy – light, heat.
Soil composition and its role in plant life
Soil is a homogeneous system consisting of three phases: solid, liquid and gaseous.
The solid phase consists of mineral and organic parts and represents the skeleton of the soil. It includes solid particles, between which there are free voids – pores filled with water or air.
Ratio of solid, liquid and gaseous phases determines regime of supply of plants with terrestrial factors of life. It is different for various types of soils, and its change allows to regulate living conditions of plants. The optimal ratio is 2:1:1, i.e. solid phase is 50%, liquid and gaseous phases are 25% each.
Creation and maintenance of the optimal ratio of soil phases is achieved by a number of methods of tillage, melioration, fertilization, which improves water, heat, air, nutrient regimes, thereby creating favorable conditions for growth and development of plants.
Plant requirements for light
Main article: Factors of plant life: Light regime
Light energy is used by plants for photosynthesis, and its amount limits the speed of the process. The intensity and spectral composition of light affect plant growth and development. Lack of light leads to slower photosynthetic processes, which leads to starvation, stunted growth and death of plants. Excess light energy leads to suppression and burns.
Plants receive light energy from the sun, in some cases, artificial lighting is used, such as post-irradiation seedlings in greenhouses, etc.
Sunlight includes the ultraviolet spectrum, which has a bactericidal effect on microorganisms.
Plant requirements for heat
Main article: Factors of plant life: Thermal regime of soils
As K.A. Timiryazev noted, the leading role in the life of plants is played by the temperature factor. Agricultural science has by now accumulated enough information about the needs of crops in heat.
Conditional unit of heat quantity measurement is the sum of active temperatures, i.e. more than 10 °С, during vegetation period. The heat requirement of plants varies depending on the species and variety, as well as the growing season.
Determination of heat requirements makes it possible to assess crop growing conditions in a specific zone. Heat availability is particularly important during seed germination. Therefore, knowledge of these factors allows you to determine the exact timing of sowing, build a system of tillage and weed control measures.
Heat requirements determine plant resistance to frost, wintering conditions and heat tolerance.
Plant moisture requirements
Main article: Factors of plant life: Water regime of soils
Water is a key factor of plant life. Without it the growth processes in seeds do not start, it participates in synthesis of organic substances, is the medium for transformation of nutrients and biochemical reactions.
Optimal soil moisture in the root layer, which provides the best conditions for growth, is in the range of 65-90% of the lowest moisture capacity.
Transpiration coefficient is the amount of water consumed by the plant to create a unit of dry matter. It is one of the indicators of moisture consumption.
Moisture requirements may fluctuate depending on the phases of plant development. Critical growth phase is the phase of development in which water consumption is maximal.
Total water consumption is the amount of water consumed by plants per hectare, expressed in m3 or mm.
Water consumption coefficient – water consumption by plants for creation of 1000 kg of yield. It is important when calculating possible yields.
Plant requirements for nutritional elements
Main article: Plant life factors: Nutrient regime of soils
Plants for their growth, development and yield formation use organic and mineral substances, which are transformed into complex organic compounds in the process of photosynthesis.
The elemental composition of plants contains carbon, oxygen, hydrogen, nitrogen and many other elements. Carbon, oxygen, and hydrogen together account for 94% of dry matter, elementally: carbon makes up 45%, oxygen 42%, and hydrogen 7%. The remaining 6% of the dry matter consists of nitrogen and mineral elements.
The main nutrient is carbon dioxide CO2. Plants absorb about 20 billion tons of carbon from the atmospheric air every year.
Much knowledge about plant nutrition has been accumulated to date. Almost all chemical elements have been found in various plant parts, the participation of 27 elements in biochemical processes has been proven, 15 of which are essential for growth and development.
Human, through the use of fertilizers, agro-technologies, amelioration, different types and varieties, has a significant impact on the composition and soil processes.
In extensive farming, the only source of minerals for plants was their natural supply in the soil. When natural fertility was depleted, people excluded these lands from cultivation and developed new ones. The plots left behind restored fertility through natural processes for a long time. The most striking examples of this approach are the shifting and fallow systems of farming.
The transformation capacity of the soil, that is the ability to supply plants with nutrients and water introduced from outside, plays an important role in intensive farming systems. However, even this ability is not enough in today’s intensive farming systems. In addition, the soil has increased requirements for phytosanitary status and agro-technological properties. In consequence, it is required to improve the whole range of soil properties, through the use of new technologies for expanded fertility reproduction. The possibility of solving this problem is inherent in the nature of the soil as a renewable resource. But improper use of soil can lead to loss of fertility.
Regulation of plant life factors
Thanks to the accumulated experience of cultivating cultivated plants, humans have learned to regulate the inputs of the factors of life through agronomic techniques. Plants also have the ability to influence growing conditions, both through physiological processes and by influencing the external environment. For example, dead plant parts accumulate organic matter in the soil, which changes the water, nutrient and other soil regimes.
The main task of farming is to create optimal conditions for plants by regulating the amount of incoming heat, light, nutrients and water. Agronomic techniques have been developed or are being developed to meet these objectives, and research on the needs of plants, which depend largely on many different conditions, is also being conducted.
The creation of optimal conditions for plant growth and development is related to:
with changes in the physical, chemical and biological properties of the soil;
The availability of sufficient nutrients in plant-available form;
Intensity of processes of transformation of elements of a food from hardly accessible for plants into easily accessible forms, i.e. processes of mobilization and immobilization.
Regulation of space factors of plant life in agriculture is very difficult, however, is not an insurmountable task. Earth factors, on the contrary, can be regulated, creating optimal conditions for plant development.
Cosmic factors, as a more global one, are determined by the Sun’s input of light energy, which is partially transformed into heat energy. Exactly it, decisively determines climatic and zonal features of the area, which determines the possibilities of growth of certain species of plants. Moreover climate is one of factors of soil formation, i.e. it has indirect influence on growing of plants. Soil-climatic conditions determine specialization of agriculture, local character of production, i.e. composition of agricultural crops, biological properties of which most fully meet the conditions and provide high stable yields of required quality.
Sources
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: “Bylina”, 2000. – 555 с.
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.