eChapters

Introduction

In India out of the total 142 million ha of arable land around 67 per cent of them are affected by some form of land degradation due to development of salinity/sodicity or acidification, erosion by water or wind or chemical contamination. Frequent use of tillage operation under conventional cultivation system particularly in rolling terrain is one of the major causes of land degradation through accelerated water and wind erosion. The basic purpose of primary tillage operations are to control weeds, increase the availability of nutrient to plant through accelerated mineralization of organic matter, and to keep the field clean and pulverized for ease of sowing of the next crop. However the bare and pulverized top soil made them vulnerable to accelerated soil loss through runoff and also to erosion loss of soil by wind in drier agro-climatic regions. Besides soil loss, conventional tillage operation breaks the soil aggregates and exposes the soil organic carbon locked inside the aggregates to accelerated microbial degradation and thus results in net loss of organic carbon from the arable ecosystem.

Issues of conservation have assumed great importance in view of widespread resource degradation and the need to reduce production costs, increase profitability and make agriculture more competitive. The growing concerns for sustainable agriculture have been seen as a positive response to limits of both low-input, traditional agriculture and intensive modern agriculture relying on high levels of inputs for crop production. Sustainable agriculture relies on practices that help to maintain ecological equilibrium and encourage natural regenerative processes such as nitrogen fixation, nutrient cycling, soil regeneration, and protection of natural enemies of pest and diseases as well as the targeted use of inputs. Agricultural systems relying on such approaches are not only able to support high productivity, but also preserve biodiversity and safeguard the environment. Thus, Conservation agriculture has come up as a new paradigm to achieve goal of sustained agricultural production. It is a major step toward transition to sustainable agriculture. 

Introduction

Climate change and climatic variability are expected to reduce agricultural productivity and threaten food security of the world, particularly in developing countries. Producing enough food for the increasing population in a background of decreasing resources and a changing climate scenario, is a challenging task. Agriculture, forestry and land use change account for about 30% of greenhouse gases (GHGs) emissions. Therefore, mitigation of GHGs emission while enhancing production is another challenge in agriculture.
 
Conservation agriculture (CA), with the three core inter-linked principles of minimizing mechanical soil disturbance, enhancing organic matter cover on soil and diversification of crops, is a viable option for sustainable agriculture with an effective solution to climate change adaptation and mitigation. The principles can be integrated and applied into most of the rainfed and irrigated production systems including horticulture, agro-forestry, organic farming, rotational farming and integrated crop-livestock systems to strengthen ecological sustainability. Worldwide about 105 Mha land is under CA and the area is increasing. However countries like USA, Brazil, Argentina, Canada and Australia occupy about 90% of the area under CA. The CA, which is advocated as an alternative to the conventional production system for improving productivity and sustainability, is now adopted by many countries and agencies as a lead model for sustainable agricultural intensification.

Introduction

Cycling of plant material is required for any production system for biological activity, humus formation and thereby formation of a dark colored top soil. Incorporation of biomass results in production and proliferation of soil biota. But under annual crops compared to forest, production is much less, the biomass is largely removed, the soil is tilled several times each year. Consequently, less food and moisture are available for earthworms, insects, micro-flora and fauna; and their habitats are repeatedly disturbed or destroyed. Therefore, the primary need of our agricultural activities is to feed soil organisms (bacteria, fungi, earthworms etc.) and to regulate their living conditions while protecting them from chemical and mechanical impacts.

Introduction

Agriculture is the most important sector in India accounting for 13.7 per cent of the country’s GDP and employs more than 60 per cent of the labour force. Our country has recorded the highest food grain production of 257 million tonnes during 2012-13, under favourable weather conditions those prevailed throughout the year. The mission of increasing food grain production, though realized to a commendable extent at present, but under risk due to climatic aberrations and reduced availability of land, water, nutrients along with poor and continuous degradation of the resources to cope up with the demands of increasing population. Although the country had attained self sufficiency in food grain production through intensification of agriculture with high–yielding varieties, fertilizer application and chemical pest control during the green revolution, productivity is still low and is stagnating.

Object: Effect of ethylene on regulation of stomata.

Material required: Plant leaves, ethaphon, ACC, double distilled water, measuring cylinder, beaker and electric balance.

Theory: Ethylene is a plant hormone that regulates many aspects of growth and development. Despite the well-known association between ethylene and stress signalling, its effects on stomatal movements are largely unexplored. Here, genetic and physiological data are provided that position ethylene into the Arabidopsis guard cell signalling network, and demonstrate a functional link between ethylene and hydrogen peroxide (H₂O₂). In wild-type leaves, ethylene induces stomatal closure that is dependent on H₂O₂ production in guard cells, generated by the nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase AtrbohF. 

Object: Yield estimation of kharif crops.

Material required: Polythene bags, balance, gunny bags or baskets, pans and harvesting equipment like sickle, knife etc.

Theory: Yield is the ultimate objective of cultivating agricultural plants. Different plant parts constitute the economic yield in different crops, like grain in cereals, pulses and oil seeds, vegetative parts or fruits in record yield at the correct maturation stage. Do not allow excessive wilting or drying of the material. Estimate yield in a sufficiently large sample. Materials required only a representative crop to estimate yields. (Do not select plants of any particular type. Do not damage any plant part vegetable crops; bark or out growth in fiber crops (jute, cotton); and the entire plant in fodder crops. The yield per unit area (per M₂ or ha) is the product of yield per plant multiplied by the number of plants per unit area. It is, therefore, essential to know the yield components per plant as well as per unit area.

Object: Growth analysis: Calculation of growth parameters. 

Material required: Primary data collected from individual plants or derived from whole canopies. 

Theory: The growth analysis study provides information on the growth of plants or of a plant community in a precise way with the available’ raw data. The study also provides precise information on the nature of plant and environment interaction in a particular habitat.

Object: To demonstrate the measurement of growth in plants with the help of Arc auxanometer. 

Material required: Potted plant, Arc auxanometer, rope and weight.

Theory: Growth is a permanent change in plants with respect to its size, form, weight and volume.

Object: Determination of the viability of seeds by tetrazolium test. 

Material required: Healthy seeds, tetrazolium solutions, beakers, water and petridishes. 

Theory: Viability of seeds shows their potential towards germination.

Object: Breaking of seed dormancy to facilitate germination.

Material required: Seeds, water, sharp needle, sharp razor, sandpaper, acids, Potassium nitrate and gibberellic acid. 

Definition: Inability of a viable seed to respond the favorable environmental conditions for germination is known as dormancy.

Object: To demonstrate the optimum conditions for seed germination. 

Material required: Beaker, glass slide, bean seeds, thread and water.

Theory: Germination is a process by which the embryo in the seed becomes activated and begins to grow into a new seedling under favorable conditions. Food is stored in the seeds in dry conditions but the developing embryo cannot utilize this dry food. Food can be utilized in liquid form only and seeds can utilize only dissolved oxygen. Excess water stop germination because once all the dissolves oxygen is utilized by the seed, further germination is not possible as the life supporting oxygen is lacking. Suitable temperature is necessary because low temperature retards the embryo activity and high temperature destroys the delicate embryo tissue. Seed usually germinate between 0oC to 50oC temperature and the optimum temperature is lies between 25 to 30oC. During germination rapid cell division takes place. Energy is required for cell division. This energy is obtained from oxidation. The oxygen is required for oxidation is supplied by the air.

Object: To determine respiratory quotient of different types of respiratory substrates.

Object: To demonstrate that oxygen is used up during respiration. 

Material required: A conical flask, some germinating seeds, glass tube having two bends at right angles, mercury, beaker, small tube and caustic potash (KOH).

Theory: Plants at some stage have a capacity to respire more rapidly in presence of oxygen i.e. aerobic respiration. In this process, oxidation of carbohydrate occurs resulting in conversion of carbohydrate into carbon dioxide (CO₂) and water with release of large amount of energy.

Object: To demonstrate anaerobic respiration. 

Material required: Soaked pea or gram seeds, mercury, test tube stand, forceps and KOH pellets. 

Theory: Generally, plants at certain stage have the capacity to respire in absence of oxygen i.e. anaerobic respiration. In this process, oxidation of carbohydrate takes places, ethyl alcohol and CO2 being end products and only a little amount of energy is liberated-

Object: To demonstrate that O₂ is evolved during photosynthesis. 
 

Material required: Hydrilla plant, beaker, test tube, funnel, pond water and pyrogallol. 
 

Theory: Oxygen is a byproduct of photosynthesis, which is evolved in presence of light and chlorophyll during photosynthesis.

Object: To demonstrate that light and carbon dioxide are essential for photosynthesis (Moll’s half leaf experiment). 

Material Required: A potted plant, a wide mouthed bottle, caustic potash, splits of rubber Cork and vaseline etc. 

Object: To demonstrate unequal transpiration by the two leaf surfaces from four leaf method. 

Material required: four leaves of china rose or any dorsiventral leaves, two stands, thread and grease or vaseline. 

Theory: Transpiration is a process in which loss of water occurs in the form of water vapour from the aerial parts of the living plant. 

Method: Take four leaves of equal size from a plant (e.g. China rose). Now apply or smear the vaseline on the four leaves as follows:

Object: To find out the relation between transpiration and absorption. 

Material Required: Wide mouthed glass bottle, with a narrow graduated side tube, split rubber cork, water and a plant with intact root system.

Theory: The loss in weight of plant indicates the amount of water transpired. And fall in water level of the side tube indicates the amount of water absorbed. This shows that amount of water transpired is normally equal to the amount of water absorbed by the plant roots.

Object: To measure the rate of transpiration by using Ganong’s potometer

Material required: Ganong’s potometer, beaker, wax or vaseline, stop watch and twig or a branch of a plant.

Theory: The amount of water absorbed is almost equal to the amount of water transpired. The difference between the two amounts is negligible. 

Method: Potometer consists of wide mouthed tube fitted with a hard cork in which a twig or branch of a plant is inserted. Other end of tube is dipped in beaker. One half of the tube is graduated. The apparatus is filled with water using the reservoir. An air bubble is inserted in the tube as shown in figure.