Genetic factors affecting crop production

The increase in crop yields and other desirable characters are related to Genetic make-up of plants.

• High yielding ability
• Early maturity
• Resistance to lodging
• Drought flood and salinity tolerance
• Tolerance to insect pests and diseases
• Chemical composition of grains (oil content, protein content)
• Quality of grains (fineness, coarseness)
• Quality of straw (sweetness, juiciness)

The above characters are less influenced by environmental factors since they are governed by genetic make-up of crop.

External factors

• Climatic
• Edaphic
• Biotic
• Phsiographic
• Socio-economic

CLIMATIC FACTORS

Nearly 50 % of yield is attributed to the influence of climatic factors. The following are the atmospheric weather variables or elements of weather which influences crop production.

• Precipitation
• Temperature
• Atmospheric humidity
• Solar radiation
• Wind velocity
• Atmospheric gases

• Precipitation

1. Precipitation includes all water which falls from atmosphere such as rainfall, snow, hail, fog and dew.
2. Rainfall one of the most important factor influences the vegetation of a place.
3. Total precipitation in amount and distribution greatly affects the choice of a cultivated species in a place.
4. In heavy and evenly distributed rainfall areas, crops like rice in plains and tea, coffee and rubber in Western Ghats are grown.
5. Low and uneven distribution of rainfall is common in dryland farming where drought resistance crops like pearl millet, sorghum and minor millets are grown.
6. In desert areas grasses and shrubs are common where hot desert climate exists.
7. Though the rainfall has major influence on yield of crops, yields are not always directly proportional to the amount of Precipitation as excess above optimum reduces the yields.
8. Distribution of rainfall is more important than total rainfall to have longer growing period especially in drylands.

• Temperature

Temperature is a measure of intensity of heat energy. The range of temperature for maximum growth of most of the agricultural plants is between 15 and 40ºC. The temperature of a place is largely determined by its distance from the equator (latitude) and altitude.

1. It influences distribution of crop plants and vegetation.
2. Germination, growth and development of crops are highly influenced by temperature.
3. Affects leaf production, expansion and flowering.
4. Physical and chemical processes within the plants are governed by air temperature.
5. Diffusion rates of gases and liquids changes with temperature.
6. Solubility of different substances in plant is dependent on temperature.
7. The minimum, maximum (above which crop growth ceases) and optimum temperature of individual’s plant is called as cardinal temperature.

Atmospheric Humidity (Relative Humidity – RH)

Water is present in the atmosphere in the form of invisible water vapour, normally known as humidity. Relative humidity is ratio between the amount of moisture present in the air to the saturation capacity of the air at a particular temperature. If relative humidity is 100% it means that the entire space is filled with water and there is no soil evaporation and plant transpiration.

1. Relative humidity influences the water requirement of crops
2. Relative humidity of 40-60% is suitable for most of the crop plants.
3. Very few crops can perform well when relative humidity is 80% and above.
4. When relative humidity is high there is chance for the outbreak of pest and disease.

Solar radiation (without which life will not exist)

From germination to harvest and even post-harvest crops are affected by solar radiation. Biomass production by photosynthetic processes requires light. All physical process taking place in the soil, plant and environment are dependent on light. Solar radiation controls distribution of temperature and there by distribution of crops in a region. Visible radiation is very important in photosynthetic mechanism of plants. Photo synthetically Active Radiation (PAR – 0.4 – 0.7μ) is essential for production of carbohydrates and ultimately biomass.

0.4 to 0.5 μ – Blue – violet – Active

0.5 to 0.6 μ – Orange – red – Active

0.5 to 0.6 μ – Green –yellow – low active

Photoperiodism is a response of plant to day length

Short day – Day length is <12 hours (Rice, Sunflower and cotton), long day – Day length is > 12 hours (Barley, oat, carrot and cabbage), day neutral – There is no or less influence on day length (Tomato and maize).

Phototropism –– Response of plants to light direction. Eg. Sunflower

Photosensitive – Season bound varieties depends on quantity of light received

Wind velocity

1. The basic function of wind is to carry moisture (precipitation) and heat.
2. The moving wind not only supplies moisture and heat, also supplies fresh CO₂ for the photosynthesis.
3. Wind movement for 4 – 6 km/hour is suitable for more crops.
4. When wind speed is enormous then there is mechanical damage of the crops (i.e.) it removes leaves and twigs and damages crops like banana, sugarcane
5. Wind dispersal of pollen and seeds is natural and necessary for certain crops.
6. Causes soil erosion.
7. Helps in cleaning produce to farmers.
8. Increases evaporation.
9. Spread of pest and diseases.

Atmospheric gases on plant growth

• CO₂ – 0.03%, O₂ – 20.95%, N₂ – 78.09%, Argon – 0.93%, Others – 0.02%.
• CO₂ is important for Photosynthesis, CO₂ taken by the plants by diffusion process from leaves through stomata
• CO₂ is returned to atmosphere during decomposition of organic materials, all farm wastes and by respiration
• O₂ is important for respiration of both plants and animals while it is released by plants during Photosynthesis
• Nitrogen is one of the important major plant nutrient, Atmospheric N is fixed in the soil by lightning, rainfall and N fixing microbes in pulses crops and available to plants
• Certain gases like SO₂, CO, CH₄, HF released to atmosphere are toxic to plants

EDAPHIC FACTORS (soil)

Plants grown in land completely depend on soil on which they grow. The soil factors that affect crop growth are

• Soil moisture
• Soil air
• Soil temperature
• Soil mineral matter
• Soil organic matter
• Soil organisms
• Soil reactions

Soil moisture

• Water is a principal constituent of growing plant which it extracts from soil
• Water is essential for photosynthesis
• The moisture range between field capacity and permanent wilting point is available to plants.
• Available moisture will be more in clay soil than sandy soil
• Soil water helps in chemical and biological activities of soil including mineralization
• It influences the soil environment Eg. it moderates the soil temperature from extremes
• Nutrient availability and mobility increases with increase in soil moisture content.

Soil air

• Aeration of soil is absolutely essential for the absorption of water by roots
• Germination is inhibited in the absence of oxygen
• O₂ is required for respiration of roots and microorganisms.
• Soil air is essential for nutrient availability of the soil by breaking down insoluble mineral to soluble salts
• For proper decomposition of organic matter
• Potato, tobacco, cotton linseed, tea and legumes need higher O₂ in soil air
• Rice requires low level of O₂ and can tolerate water logged (absence of O2) condition.

Soil temperature

• It affects the physical and chemical processes going on in the soil.
• It influences the rate of absorption of water and solutes (nutrients)
• It affects the germination of seeds and growth rate of underground portions of the crops like tapioca, sweet potato.
• Soil temperature controls the microbial activity and processes involved in the nutrient availability
• Cold soils are not conducive for rapid growth of most of agricultural crops

Soil mineral matter

• The mineral content of soil is derived from the weathering of rocks and minerals as particles of different sizes.
• These are the sources of plant nutrients eg; Ca, Mg, S, Mn, Fe, K etc

Soil Organic matter

• It supplies all the major, minor and micro nutrients to crops
• It improves the texture of the soil
• It increases the water holding capacity of the soil.
• It is a source of food for most microorganisms
• Organic acids released during decomposition of organic matter enables mineralisation process thus releasing unavailable plant nutrients

Soil organisms

• The raw organic matter in the soil is decomposed by different microorganisms which in turn releases the plant nutrients
• Atmospheric nitrogen is fixed by microbes in the soil and is available to crop plants through symbiotic (Rhizobium) or non-symbiotic (Azospirillum) association

Soil reaction (pH)

• Soil reaction is the pH (hydrogen ion concentration) of the soil.
• Soil pH affects crop growth and neutral soils with pH 7.0 are best for growth of most of the crops
• Soils may be acidic (<7.0), neutral (=7.0), saline and alkaline (>7.0)
• Soils with low pH is injurious to plants due high toxicity of Fe and Al.
• Low pH also interferes with availability of other plant nutrients.

BIOTIC FACTORS

Beneficial and harmful effects caused by other biological organism (plants and animals) on the crop plants

Plants

• Competitive and complementary nature among field crops when grown together
• Competition between plants occurs when there is demand for nutrients, moisture and sunlight particularly when they are in short supply or when plants are closely spaced
• When different crops of cereals and legumes are grown together, mutual benefit results in higher yield (synergistic effect)
• Competition between weed and crop plants as parasites eg: Striga parasite weed on sugarcane crop

Animals

• Soil fauna like protozoa, nematode, snails, and insects help in organic matter decomposition, while using organic matter for their living
• Insects and nematodes cause damage to crop yield and considered as harmful organisms.
• Honey bees and wasps help in cross pollination and increases yield and considered as beneficial organisms
• Burrowing earthworm facilitates aeration and drainage of the soil as ingestion of organic and mineral matter by earthworm results in constant mixing of these materials in the soils.
• Large animals cause damage to crop plants by grazing (cattle, goats etc)

Physiographic factors:

• Topography is the nature of surface earth (leveled or sloppy) is known as topography. Topographic factors affect the crop growth indirectly.
• Altitude – increase in altitude cause a decrease in temperature and increase in precipitation and wind velocity (hills and plains)
• Steepness of slope: it results in run off of rain water and loss of nutrient rich top soil
• Exposure to light and wind: a mountain slope exposed to low intensity of light and strong dry winds may results in poor crop yields (coastal areas and interior pockets)

Socio-economic factors

• Society inclination to farming and members available for cultivation
• Appropriate choice of crops by human beings to satisfy the food and fodder requirement of farm household.
• Breeding varieties by human invention for increased yield or pest & disease resistance

The economic condition of the farmers greatly decides the input/ resource mobilizing ability (marginal, small, medium and large farmers) https://www.researchgate.net/file.PostFileLoader.html?id…assetKey

Other factors include

Loss of cropland

Cropland has been lost because of various reasons, the most noteworthy of them being as follows:

• Rapid urban development and accompanying development of infrastructure has been primarily at the cost of agricultural land. As settlements, towns and cities grow; adjacent cropland is reduced to accommodate roads, industries and buildings. With expected increase in world urban population from about 3 billion people in 2000 to 5 billion in 2030 (according to UN projections), built-up area is likely to increase to about 0.7 per cent by 2030. This is likely to be at the expense of cropland.
• Cropland area has been lost to degradation because of deforestation and inappropriate agricultural practices. It is estimated by several researchers that globally, 20,000-50,000 sq. km. of land are lost annually, mainly because of soil erosion, the losses being some 3-6 times higher in Africa, Latin America and Asia than in North America and Europe. The major areas of degradation are in Africa, south of the equator, South-East Asia, Southern China, North-Central Australia, and the pampas of South America. More than 900,000 sq km of land in sub-Saharan Africa is threatened with irreversible degradation if nutrient depletion is allowed to continue. In most parts of Asia, forest is shrinking, agriculture is gradually expanding to marginal land, and nutrient leaching and soil erosion are accelerating land degradation.
• Changes in the proportion of non-food crops to food crops could have a significant impact on available cropland for food production. Biofuels (which include biodiesel from palm oil and ethanol from sugarcane, corn and soya-bean) have become prominent given the circumstances of high oil prices and the initial perception that they are environmentally friendly in reducing carbon dioxide emissions. North America and Europe have set high targets to convert to biofuels. Many countries, such as Indonesia and Malaysia, see’ in biofuels an opportunity to improve rural livelihoods and boost the economy through exports. Though biofuels are a potential low-carbon energy source, the conversion of rainforests, peatlands, and savannas to produce biofuels in the US, Brazil and South East Asia may actually release more carbon dioxide than the reductions in greenhouse gases brought about by using biofuels as an energy source. The main potential of biofuels lies in using biomass grown in wastelands or abandoned agricultural land. It has also been pointed out that growing crops for biofuels competes with food production; according to some calculations, the corn equivalent of a full tank of ethanol in a 4-wheel drive suburban utility vehicle (SUV) could practically feed one person for a year. As a consequence of diverting cropland to biofuel production, food prices are expected to rise drastically. Production of other non-food crops, such as cotton, is also projected to increase. Again, this would be at the expense of food production.

Reduced yields

Due to environmental degradation and loss of ecosystem components, there would be reduced yield of food crops. Unsustainable practices in irrigation and production may lead to increased salinisation of soil, depletion of soil nutrients, and erosion. This, in turn, will cause lower yields. The productivity of some lands has declined by 50 per cent due to soil erosion and desertification.

Africa is considered to be the continent most severely affected by land degradation. Global climate change can also affect food production: by changing overall growing conditions (rainfall distribution, temperature regime); by inducing more extreme weather such as floods, storms, and drought; and by increasing extent, type and frequency of infestations, including that of invasive alien species. All this would be bound to adversely affect yield.

An important factor in agricultural, yield is water: agriculture accounts for nearly 70 per cent of water consumption. Water scarcity is expected to affect over 1.8 billion people by 2025 according to the World Health Organisation. This could cause not only health problems but also impact farm productivity. Watersheds have been damaged.

The global consumption of both ‘blue’ water (withdrawn for irrigation from lakes, rivers and aquifers) and ‘green’ water (precipitation) by rain-fed and irrigated agriculture and other terrestrial ecosystems is steadily increasing.

Water may be considered as one of the most limiting factors in increasing food production. Over- extraction of water resources from aquifers and rivers has led to much loss of this resource. River discharge has decreased in many areas mainly as a result of human action and use. This water scarcity is likely to reduce yields of food grains, as 40 per cent of world’s crop yields is based on irrigation.

Invasive Alien Species

Invasive alien species—pests and diseases—are another threat to food production. Pests and pathogens have had particularly severe effects on crop yields in the world’s poorest and most food insecure region of sub-Saharan Africa. Increased climate extremes may encourage the spread of plant diseases, pest outbreaks and weeds. The spread of invasive alien species also occurs in the provisions of humanitarian food aid in times of famine and disaster emergencies, as lower sanitary and phytosanitary standards apply to such food aid.

The spread of plant pests, weeds and animal diseases thus occurs across physical and political boundaries, and constitutes a threat to food security. Those most affected by invasive alien species are the small and subsistence farmers and others directly relying on ecosystem services, as they depend on the safety net provided by natural ecosystems in terms of food, access to fuel, medicinal products and construction materials, and protection from natural hazards.

Aquaculture and Fisheries

Fisheries— freshwater and marine—supply about 10 per cent of world human calorie intake. It is estimated that fish contributes up to 180 kcal per day, but these heights are reached only in a few countries where there is a strong preference for fish or there is a marked lack of alternative protein foods grown locally. Recommending an increased intake of fish, however, needs to be balanced against concerns of sustainability.

The world’s fisheries have steadily declined since the 1980s, reported the United Nations Environment Programme (UNEP) in 2008. Over half the world’s catches are made in less than 7 per cent of the oceans, and these regions are already facing an increasing damage from bottom trawling, pollution, dead zones (areas of the coasts starved of oxygen), and invasive species infestations. Overfishing and bottom trawling are reducing fish stocks and degrading fish habitats, threatening the entire productivity of ocean biodiversity hotspots.

It is reported that about 80 per cent of the world’s primary fisheries stocks are exploited close to or even beyond their optimum harvest capacity. Large areas of productive seabeds on some fishing grounds have been damaged. Overfishing and pollution have led to infestation of the world’s fishing grounds by invasive species, mainly through ballast water (as seen all along major shipping routes).

Eutrophication from excessive inputs of phosphorus and nitrogen through sewage and agricultural run-offs is a major threat to freshwater and coastal marine fisheries. Eutrophication and excessive fishing leads to loss or depletion of marine food resources, as has happened in the Gulf of Mexico, the Pacific Northwest, coastal China and many parts of the Atlantic.

The limit to the availability of wild marine fish for aquaculture feed is also bound to limit the further growth of aquaculture. In some regions such as in parts of Africa and South East Asia, increase in fisheries has been an important contributor in the increase of food supply in recent times. A decline in fisheries will, therefore, have a major impact on the livelihoods and nutrition of millions of people.

Livestock

There has been an increasing pressure on the livestock sector to meet the growing demand for high-value animal protein. Annual meat production is projected to rise to more than 375 million tonnes by 2030 from about 200 tonnes in 1997-98. Various factors are at work in this increase in demand for livestock products. Mainly, with increased income levels, it is seen that consumption of animal protein (meat, milk, eggs) increases at the cost of staple foods (cereals, for example).

As urbanization spreads, it stimulates improvements in infrastructure, including cold chains, which permit trade in perishable foods. City dwellers tend to have a more varied diet (rich in animal proteins and fats) than rural communities.

There has been a noteworthy increase in consumption of animal products in countries, such as Brazil and China, though the levels are still below the consumption levels in North American and most other industrialised countries. Excessive consumption of livestock products, however, can have detrimental effects on health due to excessive intake of fat. Intake of dietary fats has increased practically everywhere (most in North America) except in Africa. Rising incomes in the developing world have also led to an increase in the availability and consumption of energy-dense high-fat diets.

The growing demand for livestock products is likely to have adverse impact on the environment. It is estimated that the area required for production of animal feed is approximately one-third of all arable land. More land may get diverted from crops for grazing and feed production for the meat industry. Deforestation has increased especially in Latin America because of the expansion of land for livestock grazing. Overgrazing brings its own problems in the form of land degradation.

According to FAO, over 70 per cent of all grazing land in dry areas is considered degraded mostly because of overgrazing, compaction and erosion attributable to livestock. Increased demand for meat also results in an accelerated demand for water, and feed crops such as maize and soyabean. In addition, large-scale industrial production of livestock products tends to be located close to urban centres and could lead to environmental and public health risks. Source: http://www.yourarticlelibrary.com/geography/top-5-factors-affecting-crop-production/42222/