eChapters

5.1 Introduction

Phosphorus fertilization is a problem in acid soils due to the high fixation characteristics of these soils. Soluble phosphorus carriers such as triple super phosphate tend to get reverted into insoluble and slowly soluble forms, for e.g. iron and aluminium phosphates.  Some soils in Mauritius have been shown to fix up to 90% of applied phosphorus. The fixation characteristics as related to soil properties have been studied for some soils of Mauritius. Rock phosphate offers a good alternative or complement to triple super phosphate.  In volcanic soils of Chile it is recommended to apply rock phosphate in combination with triple super phosphate because of the high phosphorus-retention capacity of these soils.  However, in Western Australia it has been shown that rock phosphate response is low. Possible explanations are slow dissolution of rock phosphate due to the moderately acid pH (5.5 -6.5), low pH-buffering capacity, low calcium absorption in soil, which increases concentration of calcium in soil solution, and poor water holding capacity of these soils.

The biofilm formation is usually assayed by using Congo Red Agar (CRA) plate test. According to a method developed by Freeman et al., (1989) the isolates are stored in nutrient agar slants and screened for biofilm formation ability using CRA plates. Biofilm forming strains are observed as dark black colonies while others as red colonies on the CRA plates. Recently, the concept of these biofims have changed with new imaging technologies, biochemical methods and molecular ecosystem biology tools. A biofilm structure can be observed in 3-D form to the nano-scale level (Neu and Lawrence, 2015). A lot of studies are being conducted on the physiology of the biofilm cells, the genotypic and phenotypic variation among the biofilm community, as well as the biofilm metabolome, proteome and transcriptome (Raes and Bork, 2008). This will help in the the development of efficient methods to control deleterious biofilms (clinical biofilms, food contaminants, biofouling on industrial equipment and on ship hulls) and to enhance and modulate beneficial ones

Q1. Resistance in tetracycline is due to mutational changes in

1. Tet A gene
2. Kat G
3. Par C par E
4. Inh A

Q2. Single step mutation can be seen in

1. Erythromycin
2. Tetracycline
3. Chloramphenicol
4. Rifampicin

Q3. Multistep mutation is observed in

1. Streptomycin
2. Rifampicin
3. Both A and C
4. Tetracycline

The lack of mechanistic understanding of probiotic activity is a major drawback for the prediction of safety of probiotic intervention. The complex gut-associated microbial ecosystem and nutritionally related factors are the most important environmental triggers for the development and modification of chronic degenerative diseases including immune and metabolic pathologies. In fact, the interaction between the gut microbial ecosystem and the host is considered to be a critical factor in overall health or disease. Whether probiotics will exert protective, harmful, immune-stimulating or immune-suppressing effects on a host is dependent on the interaction between the microbial signals, the genetic make-up of the host and the effects by the environment. Many studies have revealed that certain probiotic bacteria stimulate immune cell proliferation and activity as evidenced by the production of cytokines and antibodies, thereby enhancing the effectiveness of the immune response against pathogens. Ng et al. (2009)

ABSTRACT

The antagonistic organisms are known to bring out action on the pathogen by various mechanisms. Based on in vitro screening of epiphytic microbes from cocoa pod surface against Phytophthora palmivora, the incitant of pod rot of cocoa, a promising isolate of Trichoderma viride and two isolates of Pseudomonas fluorescens were selected. The mechanisms of antagonistic action of these selected epiphytic antagonists against P. palmivora were studied in comparison with the standard cultures of T. harzianum and P. fluorescens. The selected epiphytic fungal antagonist T. viride and standard culture of T. harzianum were found to be efficient parasites of P. palmivora. The hyphae of the pathogen were seen tightly held by coiling with hyphae of the fungal antagonists. The hyphae of the antagonists penetrated the host hyphae at several points and grew to its inner cavity. The fungal antagonists also caused disintegration of the pathogen hyphae, besides free intermingling, which resulted in malformation of host hyphae. The ability of the two epiphytic P. fluorescens isolates and standard culture of P. fluorescens in producing HCN and siderophores was assessed. It was found that these isolates produced HCN and siderophores in appreciable levels thereby suppressing the P. palmivora. Though, more than one mechanism may operate in suppressing the pathogen, the relative importance of a particular mechanism may vary with different conditions, which needed to be further investigated.

Mechanism of Bioinputs explains the biological processes through which beneficial microorganisms and other bioinputs influence plants, pathogens, and agricultural ecosystems. The chapter examines direct and indirect plant-growth-promoting mechanisms of rhizobacteria, mycorrhizal fungi, endophytes, and biocontrol microbes. It also covers entomopathogenic bacteria, fungi, nematodes, viruses, and the modes of action of microbial and botanical biopesticides, predators, parasitoids, and semiochemicals. Environmental factors, microbial variability, pathogen interactions, and relationships with other organisms are considered as influences on biocontrol performance. The chapter therefore connects biological mechanisms with practical application, helping readers understand why particular bioinputs work under specific agricultural conditions. across varied farming conditions.

As discussed in previous chapters, the damage to the plants due to frost occurs as a result of frost-induced freezing and not merely because of the low temperature exposure. The cells of sensitive plant species get injured when the temperature drops below a critical level. When the damage caused is associated with sub-zero temperature, it is called freezing injury. And, when it is caused due to a temperature above 00 C, it is called chilling injury.

Various types of cropping systems are practiced in a farm or region. They should be evaluated to find out their stability and relative advantages in yield. Again, comparisons may be made with reference to land use efficiency, biological potential and economics. Following are the important indices for assessment of competition and yield advantage:

1. Relative yield total (RYT): The oldest establishment measure of the yield advantage of crop mixtures is the Relative Yield Total. The RYT index was designed as a measure of the extent to which various crop components shared common resources, rather than as a direct measure of yield advantage.

Hybrid technology is one of the options to boost crop productivity. Hybrids give more yield than improved varieties under optimum crop production conditions. Further, uniform size, earliness, better adaptability to adverse environments, better transportability due to better keeping quality and resistance to stresses are certain additional advantages of growing hybrids with better monetary return to the growers. Hence in coming years, hybrid technology has to go a long way in our country to meet the future challenges (Kalloo et al., 2000). Thus, it is pertinent to have an overview of the methods of the hybrid seed production technology. Various methods are as follows:

ABSTRACT

Heavy metal contaminated soils are biologically inactive and extremely poor in soil fertility status. These metals are highly resistant and cannot be easily degraded by either chemical reactions or amendments. Microorganisms are biological softwares capable of degrading the metals efficiently. Among microorganisms, mycorrhizas are known to circumvent metal toxicities through a series of processes that assist in immobilization in biological systems which converts toxic metals into less or nontoxic forms. There are five mechanisms such as biosorption, solubilization, hyphal transport, detoxification and dilution are involved in promoting tolerance of host plants to heavy metal toxicities. These processes are strategies that can be exploited to phytoremediate the contaminated soils. The phytoremediation strategies encompass tolerance of mycorrhizal fungi, phytostabilization (preventing entry of heavy metals into plants), phytoextraction (luxuriant uptake and transport to shoots) and intercropping or crop rotation with mycorrhizal dependent hyperaccumulators or non-hyperaccumulators. Despite mycorrhizas are natural, the indigenous population is not sufficient enough to induce tolerance of host plants to abiotic and biotic stress conditions. This necessitates adopting recommended agronomic practices to promote mycorrhizal colonization in natural agro-ecosystem or to derive full benefits from phytoremediation strategies. Thus mycorrhizas are important naturally occurring microorganisms capable of withstanding highly contaminated metal sites and offer protection against phytotoxicities caused by heavy metals.

Introduction
The advent of antibiotics, beginning with penicillin in 1941, transformed medicine by rendering bacterial infections treatable [1]. However, antimicrobial resistance (AMR) has emerged as a profound threat, enabling bacteria to survive in the presence of drugs designed to inhibit or kill them and these are rooted in ancient microbial ecosystems evidenced by resistome genes in 30,000-year-old permafrost [2]. AMR has been exacerbated by human practices: approximately 50% of antibiotic prescriptions are inappropriate, 70% of global antibiotics fuel agriculture, and environmental pollution creates resistance hotspots [1]. By 2025, AMR directly causes 1.3 million deaths annually, with economic losses projected at $100 trillion by 2050 [1]. Priority pathogens, including carbapenem-resistant Enterobacteriaceae (CRE), methicillin-resistant Staphylococcus aureus (MRSA), and colistin-resistant strains via mcr-1, challenge last-resort therapies, particularly in low-resource settings [3]. This chapter delivers a technically extraordinary exploration of AMR, structured into genetic, biochemical, and evolutionary mechanisms, each elaborated with molecular precision and step-by-step clarity for learners. Genetic alterations provide the DNA-level foundation, biochemical pathways execute molecular defenses, and evolutionary forces drive adaptation and dissemination. It ensures scientific rigor and broad appeal for students, researchers, clinicians, and policymakers.
Historical Context and Global Burden
AMR emerged shortly after antibiotics’ introduction, with penicillin-resistant S. aureus identified by 1942 due to ß-lactamase production [1]. The 1960s

Biofertilizers improve the plant growth due to changes in the microbial community of rhizosphere by production of several substances. Normally, biofertilizers promote plant growth either by facilitating nutrient absorption or by secretion of plant hormones. Biofertilizers also cause inhibitory effects by acting as biocontrol agents on various pathogens so that the growth of plant is enhanced. The mode of action could be either direct or indirect methods

Email can be a wonderful tool for delivering feedback to students. Once a basic understanding of feedback’s role in learning has been established, one can begin to focus on how best to take advantage of the pedagogical functions of the com- munication medium. There is little doubt that email is changing how we commu- nicate and learn. For example, in an investigation of the effectiveness of email as a communication and instructional aid between instructors and students, Yu and Yu (2002) found “empirical evidence supporting the usefulness of e-mail as a prom- ising aid to promote student cognitive growth pertaining to computer knowledge and skills”.

Tao and Boulware (2002) suggest that email communication benefits teachers by “identif[ing] instructional focus and tak[ing] advantage of instructional moments to fit the developmental needs of their students in authentic situations”. They also find that email motivates learners, encourages authentic communication and cre- ates new learning opportunities.

Thank you, Dr Tikoo, for a nice introduction and thanks to ATPBR for inviting me to deliver this WebCon. I would like to start with a small introduction that this particular talk is structured as a general introduction to thrips and thrips-transmitted viruses. There is a bit of interest in everyone with regard to the black thrips which has caused havoc in the last couple of years. The topic has significant importance to plant breeders with regard to the new invasive Western Flower thrips, one of the most dreaded thrips, across the globe and the problems associated with the management of resistance in protected cultivation, and, finally how do we go about with regard to the entire management of the thrips and thrips-transmitted virus problems.

Introduction

India’s food problem dates back prior to independence. In the beginning, India’s food problem was one of scarcity, shortage of rice after the separation of Myanmar (Burma) from India in 1937 and shortage of wheat, also after the partition of the country in 1947. Initially, the major concern was to increase the domestic supplies either through increased production or through imports or through both. In the second half of the 1950s and during the 1960s the major concern was shifted to control of food grains prices. The Government of India entered into an agreement in 1956 with the USA known as PL 480 agreement for the import of rice and wheat. The Government found the PL 480 food imports a good tool to stabilize food prices in the country. Infact, PL 480 imports were the basis of our agricultural and industrial development. The frequent occurrence of flood and drought, food shortage resulted famine in several corners of the country during pre-independence period and even after independence.

Mechanization of agriculture is essential for optimal utilization of vital inputs for crop production system such as soil, water, seed, fertilizer, pesticide and labour force leading to higher productivity and reduced cost of production for greater profitability. Thus with the support of mechanization, the agrarian sector as an enterprise needs to become sustainable and economically competitive which coincides with the objectives of the Integrated farming System concept. Mechanization also imparts capacity to the farmers to carry out farm operations with dignity, comfort and freedom from drudgery, making the farming agreeable vocation for educated rural youth as well. It helps the farmers to achieve timeliness and precisely meter and apply costly input for better efficacy and achieve higher productivity with reduced application of inputs. Small and marginal farmers now make use of high capacity agricultural machines on custom hire basis to enjoy the economic benefits. As such, the broad subject of agriculture can be understood as production agriculture, which takes care the field operations in the crop production system for higher productivity and post production agriculture, better known as post harvest technology which looks for reducing the loss of produce and value addition for economic gains. The IFS outlines the need of sustainability for farmers with limited resources of land, water and economy while mechanization aims at maximizing the profitability in agricultural system with a commercial attitude. Since the availability of labour force during peak hours of need and hike in wage very often creates hindrance in production and post production agriculture, mechanization can be the right answer to harness the benefits of IFS approach.

Commercialization is essential for agricultural development, which, amongst other things, entails mechanization of agriculture to reduce the cost of production and to increase the yield of crops. In some instances, agricultural commercialization may take place even without mechanization. However, due to the ever increasing agricultural labor scarcity in developing countries, an extensive scale agricultural commercialization may not be possible without mechanization.

The various farm operations involved in crop production system are land leveling, tillage for seed bed preparation, sowing and planting, weeding and interculture, spraying, harvesting and threshing. The mechanization of all these operation has been appreciated by the farmers which are discussed in the following paragraphs.

3.1. Concept of farm mechanization

To apply the principles of engineering and technology to do the agricultural operations in a better way to increase crop yield.

Development, application and management of all mechanical aids for field operation, water control, material handling, storage and processing.

Mechanical aids include hand tools, animal drawn implements, power tillers, tractors, engines, electric motors, grain processing and hauling equipments.

Introduction

Rice (Oryza sativa), the staple food of more than half of the population of the world, is an important target to provide food security and livelihoods for millions. As a major producer and exporter of rice in the world, India reportedly produces around 152.60 MT tonnes of rice per year. When cereal crops are harvested, it is estimated that half of the process ends with agricultural waste or crop residue as straw. It is a non-edible product, often left in the field after harvesting. Traditionally, paddy straw was seen as a versatile by-product of rice cultivation because it was used in many ways including fodder for livestock and as a building material. However, the increase in productivity and area under cultivation of rice has led to a huge production of rice straw. Moreover, mechanization decreased the animal dependency and hence the feed requirement. So the most effective way of disposing of the residue is seen as burning of biomass in the paddy field. It is important to mention that open field burning is a widely practiced method all over the world however its intensity varies. For instance (National Conference, 2017) estimated that less than a quarter of rice straw is probably burnt in India compared to around half in Thailand whereas the entire residue is burnt in the Philippines. Taking farmers view into account, burning is not only a cost-effective method but it acts as an effective pest control procedure Shukla et al (2005). The short term effects of burning seems more desirable than those from soil incorporation due to the immobilization of inorganic nitrogen which occurs in the latter and can adversely affect productivity in the short term (Singh and Singh, 2001). Also, it helps to reduce diseases that may occur due to reinjection from inoculums in the straw biomass Haysa et al. (2005).The burning of rice crop residue causes atmospheric pollution by emitting trace gases which forms ‘Black Cloud’ adversely affects human health as well as environment. The air pollutants are also a hazard to people’s health particularly to those within local proximity to paddy areas. It is clear from Table 1 that crop residue is a good source of nutrients and important component for the stability of agricultural ecosystems. About 40% of the N, 30-35% of the P, 80-85% of the K and 40-50% of the S absorbed by rice remain in the vegetative parts at maturity.

Labour is one of the biggest input costs for vegetable growers. Vegetable farming is labor intensive and time consuming. Frequently, it is associated with low yield and poor quality production. The constraints are high labor requirements for land clearing, ploughing, bed forming, mulch laying, seeding, transplanting, harvesting and transporting. Mechanization is interjection of improved tools, implements, machines and other equipments between man and materials (soil, water, environment, seed, fertilizer, pesticides, growth regulators, irrigation water, agricultural produce and by-products such as fruits, vegetables, and seeds, etc.)

Sowing of Seed: It is a process of planting seeds of crops in well prepared or no till field or nursery beds/pots for raising crops in following methods:

Methods of Sowing: The sowing method is determined by the crop to be sown and resources on the disposal of farmer. There are 6 sowing methods which differ in their merits, demerits and adoption. Those are:

1.Broad casting

2.Broad or Line sowing

3.Dibbling

4.Transplanting

5.Planting

6.Putting seeds behind the plough.