eChapters

ZINC (Zn)

Chandler et al., (1932) deduced the requirement of zinc by plants while working solution for little leaf or “rosette” on peach. Zinc plays significant role in assimilation of NO₃ and for synthesis of tryptophan. Involved in biosynthesis of indole acetic acid which is responsible for f lowering and fruiting, it is an activator of several enzymes (triphosphate dehydrogenase and tryptophan synthetase), involved in photosynthesis and nitrogen metabolism.

Deficiency results in poor growth of the terminal bud. Decrease in stem length resulting in resetting and whorling of leaves. Zinc deficiency disorder in rice is called khaira. Common when zinc availability is < 0.7 ppm. White bud in maize and malformation of fruits, reduction in water uptake. Interveinal chlorosis often with necrosis and pigmentation and reduced leaf size in broad leaved crops known as little leaf and malformation of leaves.

The crops which are known to respond for zinc application are maize, rice, soyabean, castor, onion, barley, wheat, potato, sorghum and cotton

Iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), nickel (Ni), boron (B), molybdenum (Mo) and chloride (Cl) elements are known as micronutrients. The micronutrients are also called as trace elements or minor elements as they are required very small quantities by plants. The elements Fe, Zn, Cu, Mn and Ni are known as micronutrient cations and B, Mo and Cl are known as micronutrient anions and they behave accordingly in soils. Among these elements, Fe content in soil as well as plant is the highest and sometimes higher than phosphorus (P) and sulphur (S). In plant, the concentration of micronutrients often found up to 100 mg kg^-1, except that of Fe and Mn which may go up to 500 mg kg^-1 (dry weight basis). Another element, cobalt (Co) is also regarded to be essential for the growth of certain higher plants and animals, and likely to be included in the list of micronutrients. The importance of micronutrients has been realized during the past four decades when micronutrient deficiencies were observed in most of the soils in our country, where intensive agriculture is practiced.

18.1. Determination of Available Micronutrient Cations (Zn, Cu, Fe and Mn) in Soil

The available micronutrient cations (Zn, Cu, Fe and Mn) can be estimated in a single extraction with diethylene triamine pentaacetic acid (DTPA) as proposed by Lindsay and Norvell (1978). DTPA has the excellent property to combine with free metal ions in the solution forming soluble complexes. The stability constants of metal-DTPA complexes make DTPA as a most suitable extractant for simultaneous complex formation with Zn, Cu, Fe and Mn. In calcareous soil DTPA extractant may result overestimation due to excess dissolution of CaCO_3, thus releases occluded micronutrient cations which are not plant available. To avoid this excessive dissolution of CaCO₃, DTPA is buffered at pH 7.3 using triethanol amine (TEA). At this pH major part (3/4^th) of TEA is present as HTEA⁺ (protonation) and exchanges for Ca and Mg ion from the soil exchange site. This increases concentration of Ca and Mg in the solution phase and suppresses dissolution of CaCO₃. The DTPA has the capacity to complex each of the micronutrient cations 10 times of its atomic weight and it ranges from 550 to 650 ppm depending on the micronutrient cation.

The amount of cation in the extract is determined on an atomic absorption spectrophotometer (AAS). The experimental condition such as shaking time, DTPA concentration, pH and temperature during shaking influence the amount of Zn, Cu, Fe and Mn extracted. Increase in shaking time and temperature markedly influence the extractability of these cations.

25.1 Determination of Available Micronutrient cations (Zn, Cu, Fe and Mn) in Soil

The available micronutrient cations (Zn, Cu, Fe and Mn) can be estimated in a single extraction with diethylene triamine pentaacetic acid (DTPA) as proposed by Lindsay and Norvell (1978). DTPA has the excellent property to combine with free metal ions in the solution forming soluble complexes. The stability constants of metal-DTPA complexes make DTPA as a most suitable extractant for simultaneous complex formation with Zn, Cu, Fe and Mn. In calcareous soil DTPAextractant may result overestimation due to excess dissolution of CaCO₃, causingrelease of occluded micronutrient cations which are not plant available. To avoid this excessive dissolution of CaCO₃, DTPA is buffered at pH 7.3 using triethanol amine (TEA). At this pH major part (3/4^th) of TEA is present as HTEA⁺ (protonation) and exchanges for Ca and Mg ion from the soil exchange site. This increases concentration of Ca and Mg in the solution phase and suppresses dissolution of CaCO₃. The DTPA has the capacity to form complex with each of the micronutrient cations 10 times of its atomic weight and it ranges from 550 to 650 ppm depending on the micronutrient cation.

The amount of cation in the extract is determined on an atomic absorption spectrophotometer (AAS). The experimental condition such as shaking time, DTPA concentration, pH and temperature during shaking influence the amount of Zn, Cu, Fe and Mn extracted. Increase in shaking time and temperature markedly influence the extractability of these cations.

There are nine essential micronutrients, namely, iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), chlorine (Cl), vanadium (V) and nickel (Ni). Out of these, Fe, Mn, Zn, Cu and Ni (Dominic et al., 1978) are taken up by plants in their ionic form X²⁺, Mo as MoO^2-, chlorine as Cl^– form and boron as boric acid (H₃BO₃) or as its ionic form B (OH)₄ ^–. The absorption of vanadium by plants has received only limited attention (Lepp et al., 1983); it may be absorbed as cation V or vanadyl (VO²⁺) and anion vanadate (VO₄ ^3–). Bulk of the information is available on Fe, Mn, Zn and Cu, because of the acceptability of the single DTPA (Diethylene triamine pentaacetic acid)–CaCl₂ extraction test of Lindsay and Norvell (1978) for availability of all these four nutrients followed by their estimation on Atomic Absorption Spectrometer (AAS). Available B is estimated by hot 0.15 M CaCl₂ extraction method (Saha and Singh, 1997). Molybdenum data base is poor, because its determination is dif?cult and Mo de?ciency in crops has not been much noticed in India. Chloride is available in plenty in irrigation water and soil in India and has not received much attention in India.

Abstract

Impact of climate change and related stresses on plant productivity are being witnessed worldwide with developing countries being more vulnerable due to more dependency on agriculture. Microorganisms can play important role as economic and farmer’s friendly strategy to combat abiotic stress in agriculture. A wide range of microorganisms associate with plants, and many of them confer beneficial effects to their hosts through different mechanisms like production of growth promoting substances, nutrient acquisition, protection against plant pathogens etc. In the last few decades, role of microorganisms in imparting tolerance to plants against different abiotic stress has been reported in many crop plants. Under stresses conditions, plant-microbe interactions become more common towards coping with the stress. Selection and application of efficient abiotic stress tolerant microorganisms can be a fruitful strategy to alleviate negative effects of abiotic stresses in plants.

The adoption of modern agricultural technologies has culminated into serious problems of pesticide resistance in major pests, resurgence in minor pests, elimination of populations of natural parasites, predators and pollinators, environmental pollution, pesticide residues in food chain and health hazards. World Health Organization (WHO) estimates one million pesticides poisoning cases and 20,000 deaths every year globally. This is due to high pesticide residues in food chain including cereals, pulses, vegetables, fruits, milk and milk products (including mother’s milk), fishes, poultry, meat products and water. Twenty five per cent of Indian food products contain pesticide residues above tolerance level compared to only 1.2% globally.

Herbicides are the chemical substances used to kill weeds, i.e., unwanted plants that compete with crop plants for soil nutrients. Chemical herbicides are the most effective immediate solution to most weed problems. Use of chemicals, however, can be harmful to wildlife, to the environment and to humans. Chemicals are also expensive, and weeds develop resistance to the chemicals. For these reasons, there is now a move toward alternative methods of controlling the weeds. One of the most promising is biological weed control, which involves using one living organism to control the activities of another organism.

Emphasis of present day agriculture is to produce more with lesser land, water and man power. Apart from natural calamities like drought, flood etc., biotic stresses like pests, diseases and weeds also influence the crop productivity greatly. Sixty to eighty per cent of the total crop losses are attributed to the devastations caused by pests and diseases. Farmer’s income in recent years is decreasing gradually due to increased cost of inputs particularly in plant protection. The excessive dependence on chemical pesticides leads to the development of resistance in insect pests and pathogens, out breaks of secondary pests and pathogens / biotypes and occurrence of residues in food chain. To avoid this situation the concept of Integrated Pest Management (IPM)/ Integrated Disease Management (IDM) approach should be considered on top priority.

Sustainable agriculture or organic farming wherein biological inputs are maximum and chemical inputs are minimal, is drawing the attention of farmers across the world including India. For replacing chemical fertilizers, which supply plant nutrients by organic manure, the basic requirement is the availability of raw material i.e. the organic matter or biomass that can be decomposed to organic manure. The question that is often asked is what are the different sources of available biomass and how much of it is available? Different sources of biomass can be categorized as

1.    Yoghurt usually contains total milk solids in the range of

(a) 12-15%

(b) 8.5 to 11.5%

(c) 15-19%

(d) 20-25 %

2.    Yoghurt is usually manufactured by heating the pre-mix to pasteurize it to

(a) 61-62°C for 20 minutes

(b) 80-85°C for 15 to 30 minutes

(c) 80-85°C for 15 sec

(d) 71-72°C for 15 sec

Phosphorus is one of the essential nutrients for plant growth. It is an integral part of the cellular activities of the living organisms. It has a defined role in plant metabolism such as cell division, development, photosynthesis, break down of sugar, nutrient transport within the plant, transfer of genetic characteristics from one generation to another and regulation of metabolic pathways. Phosphorus is a frequently limiting macronutrient next only to nitrogen for plant growth and makes up about 0.2% of plant dry weight. The plants obtain their P requirement from the soil pool. It occurs in soil as inorganic phosphates, produced by weathering of parent rock or as organic phosphate derived from decayed plant, animal, or microorganisms.

Introduction

Global plastic production is on rise while the production in 1950 was 1.3 million tonnes wherein 359 million tons of plastic waste generation was recorded in 2018. It is predicted that the increase in plastic waste generation will reach around 250 million metric tonnes by 2050 (Haque and Fan, 2022). Plastics are now ubiquitous and has turn out to be the most dominant marine litter, which is an emerging global concern today. According to the UNEP, United Nations Environment Assembly 2017 estimates, annually around 4.8 12.7 million metric tonnes of plastics are introduced into the oceans (Haward, 2018). Owing to their lower costs, lightweight, durability and strength, virtually everything and everywhere are plastics.

Abstract
Microplastics, or plastic fragments smaller than 5 millimeters, have become prevalent contaminants in aquatic systems, arising from the breakdown of larger plastics, personal care products, and synthetic fabrics. Their presence disrupts marine and freshwater ecosystems by being consumed by wildlife, disturbing food webs, and polluting habitats. Additionally, microplastics can transport harmful pollutants and release toxic chemicals, worsening their environmental impact. Identifying these particles involves sophisticated methods such as microscopy, spectroscopy, and thermal analysis, although differentiating them from other particulates remains challenging. Major sources include direct releases, the fragmentation of larger plastic waste, and atmospheric deposition, with pathways like stormwater runoff and wastewater treatment aiding their dispersal. Addressing microplastic pollution requires a combination of regulatory measures, including bans on microbeads, technological advancements such as enhanced filtration
systems, and increased public and industry engagement. Continued research is essential for developing effective solutions, understanding microplastic pathways in the environment, and assessing their long-term effects on health.
Keywords: Microplastic, Environmental impacts, Detection, Sources, Mitigation strategies

Principle

Micropropagation is especially useful for include propagation of high value plants that grow slowly (bulbs, ferns, orchids, palms, etc), new cultivars having limited stock and high market demand (new cultivars produced via conventional breeding or genetic engineering), cultivars that are difficult to root by conventional techniques, and endangered plant species. In addition, virus elimination is possible via culture initiation from meristem explants. Also, micropropagation provides a source of sterile tissues that can be used for other tissue culture protocols, including genetic transformation.

Micropropagation is possible using multiple types of cultures; however, shoot cultures are typically employed, in which case five stages to the micropropagation process are typically recognized as outlined below. Nodal explants of rose are used for culture initiation. Three media, differing in hormone content, is employed and the explants should be evaluated for differences in axillary shoot growth and proliferation.

Abstract

Bamboo is nature’s unique gift to mankind. It has tremendous scope for use in eco-friendly agro-forestry programmes, to bring marginal lands into use. The requirement for bamboo is increasing for various traditional and industrial requirements. In India almost 99% of annual bamboo production comes from the natural forests and only about 1% is derived from plantations.

ABSTRACT

Dissected shoot tips from healthy suckers of banana var. Meitei Hei (local variety) were inoculated on Murashige and Skoog (MS) medium supplemented with different concentrations and combinations of plant growth regulators viz., NAA and BAP. After 15 days of incubation 50% of the shoot tips turned green in the medium with 5.0 mgl^-1 BAP. A maximum of 85.7% of the explants produced phenolic exudates in MS + 5.0 mgl^-1 BAP. After one month the explants were subcultured in fresh medium with the respective concentrations and combinations of plant growth regulators. After 75 days of incubation an average of 2.20 microshoots were induced in 78.57% of the explants in MS + 5.0 mgl^-1 BAP. The regeneration of shoots, leaves and roots was more proportionate in MS + 0.1 mgl^-l NAA + 0.5 mgl^-1 BAP. Under the treatment the microshoots had an average height of 1.19 cm with 4.13 leaves and 2.40 roots. The multiple microshoots were separated and subcultured on MS + 0.1 mgl^-l NAA + 0.5 mgl^-1 BAP for proper development. After 120 days the completely regenerated plantlets were hardened under green house environment.

ABSTRACT

The present experiment was conducted to standardize the composition of nutrient media for callus regeneration. Shoot tip, internodal segment, leaf and hypocotyls of seedling grown under controlled condition were used as explants for callus induction. The study revealed that explants collected from younger seedlings showed greater proliferation of callus as compared to those collected from older one. The basal MS medium as well as WP medium fortified with different concentrations of auxins and cytokinins were tried. Initial better results of profuse callus growth with green colour and compact texture having regenerative capacity were obtained by using leaf explants. In all the treatments, the callus initiation occurred at the cut ends and then spread over the surface of the explant as a result of injury. The level of auxins presumable rises and quiescent cells were stimulated to divide rapidly producing callus. The leaf segment explant induced the callus after 9.50 days in medium WPM + NAA 2.5 mg/l with maximum callus growth (976.75 mg) with green, friable callus which was difficult to subculture. White and friable callus occurred within 12.00 days in MS + 2, 4 - D 5 mg/l. The green and compact callus having vigorous growth was observed in MS + NAA 2.5 mg/l within 12.75 days when subcultured on different regeneration media proved recalcitrant for shoot regeneration. On the regeneration medium the callus turned brown while some callus proliferates to produce white growth around it and dried later on.

Experiment - 1
 
Aim: Micropropagation of Tobacco plant by leaf disc culture

Principle: The totipotency of the plant cells and tissues form the basis for in vitro cloning i.e., generation or multiplication of genetically identical plants in in vitro culture. The ability to propagate new plants from a cells or tissues of parent plant has many interesting possibilities.

Orchids belong to family Orchidaceae, which is the most highly evolved among monocotyledons with over 800 genera and 35,000 species and over 74,400 natural and manmade registered hybrids. Orchid is the first horticultural plant cloned by tissue culture methods on a commercial scale (Goh, 1990). Rapid multiplication using tissue culture techniques is an important strategy for preserving the valuable orchid wealth in India. Vegetative propagation through division of rhizomes and separation of offshoots and keikis is very slow. Both these problems can now be successfully alleviated through micropropagation. The technique has revolutionized the orchid industry and now it is possible to multiply unlimited number of desirable clones. Rotor (1949) was the first to have employed tissue culture techniques to multiply Phalaenopsis, and since then micropropagation potential of a variety of monopodial taxa has been successfully tested.