eChapters

Physiological disorders are non-pathogenic abnormalities that reduce flower quality, yield, marketability and postharvest performance. This chapter explains the causes and symptoms of physiological disorders affecting important flower crops. Environmental stresses, nutritional imbalance, temperature, humidity, light, water, growth regulators, storage conditions and other factors are examined. Disorders associated with Alstroemeria, Anthurium, Carnation, Lilium, Heliconia, Zantedeschia and other crops are described. The chapter emphasizes identification, prevention and corrective management. Understanding these disorders is essential for maintaining uniform commercial production and avoiding economic losses, particularly under protected cultivation where environmental conditions can strongly influence flower development.

Aim

Phytosynthesis of silver (Ag) nanoparticles using Cassia roxburghii aqueous leaf extract.

Introduction

The Ag nanoparticles constantly exhibit adverse effects on microbes such as inhibition and inactivation (Nasrollahi et al., 2011). The Ag nanoparticles synthesized by using various biological sources such as herbs, plants and biological organisms display excellent properties in various fields i.e., non-linear optics and intercalation materials for electrical batteries as optical receptors, catalysts in chemical reactions biolabelling and as antibacterials (Sanghi and Verma, 2009).

Plant hormones - They are defined as:

1. Small
2. Organic compounds;
3. Synthesized by the plant;
4. Active in low concentration (<10^-6);
5. Promote or inhibit growth and developmental responses;
6. Often show a separation of the site of production and the site of action (although this isn’t as clear a distinction as in animals).

Based on these criteria, would the following substances be considered hormones? Ca²⁺, sucrose, 2 4 - D, glycine, or K⁺?

8.1. Phytosanitary Capacity Evaluation (PCE): The Tool, and Its Relation to Invasive Alien Species

Phytosanitary Capacity Evaluation (PCE) is a diagnostic tool enabling a country to assess the weaknesses and strengths of its phytosanitary system in relation to its ability to fully implement the International Plant Protection Convention and other international phytosanitary obligations. PCE has also been applied as a cross-disciplinary tool among the sanitary, phytosanitary and food safety areas in the Andean subregion. Since “quarantine pests”, as defined by the convention, constitute a subset of invasive alien species, PCE results are already useful in relation to invasive alien species. PCE methodology has the potential to be further developed to cover a country’s needs in implementing Article 8(h) of the Convention on Biological Diversity.

Article XX of the International Plant Protection Convention establishes the agreement by contracting parties to promote the provision of technical assistance to facilitate implementation of the IPPC. Phytosanitary Capacity Evaluation (PCE) is the first tool approved by the Interim Commission of Phytosanitary Measures to address that commitment, assisting contracting parties to perform a needs assessment and identification of their constraints for achieving full implementation of the IPPC at the national level.

Pigeonpea (Cajanus cajan, (L.) Millspaugh, 2n = 2x = 22, an often crosspollinated crop with 20 – 70% cross-pollination, family-pea family Leguminosae or Fabaceae, genome size 808 Mbp) is a short-lived perennial shrub that is traditionally cultivated as an annual crop in developing countries.. It is grown in Asia, Eastern and Southern Africa, Latin America and Caribbean countries. On an average, it is cultivated worldwide on 4.92 million hectares (M ha) with an annual production of 3.65 Mt giving a productivity of 741 kg/ ha. India is the largest producer followed by Myanmar and Eastern and Southern Africa (principally Mozambique, Malawi, Tanzania, Kenya and Uganda.

Abstract

Any environmental variable, can adversely affect the optimal growth conditions of the plants. The stressed environment makes the plants to alter their physiology for survival rather than reproduction. Prolonged drought, intense raining, frequent floods, cold waves high and low temperatures are the predicted abiotic stresses in the future due to climate changes. Water stress is one of the important growth limiting factor which decreases plant growth during vegetative stage. Crops grown under rain-fed conditions are the most affected by seasonal variations in rainfall. Therefore failure of monsoon, high temperature and salinity usually result in water stress. In addition, it causes serious negative impacts on crop growth and yields. A greater stress tolerance capacity could also be largely attributed to the plants by the symbiotically associating microorganisms capable of modulating stress factors. The microorganisms having close association with plants are referred as plant associated bacteria (PAB), which can be grouped into rhizospheric (in vicinity of root) and rhizoplanic (on surface of root), endophytic (inside the plant tissue)  and phyllospheric (on the leaf surface ) bacteria. Among the PAB, pink pigmented facultative methylotrophic (PPFM) bacteria belonging to the  genus Methylobacterium are well known for their intimate ubiquitous occurrence in the plant.

In molecular biology and biochemistry, the ability to accurately and reproducibly measure and transfer small volumes of liquids is critical for obtaining useful results. For volumes less than 1 ml, the most common method for measuring liquid volumes involves the use of a device known as a pipetman or micro-pipette.

The pipetmen can be both fixed and variable volumes. Commonly used pipetmen are: P1000, P200, P20, P10 etc. P1000 are useful for volumes from 200 to 1000 µl. P200 are useful for volumes from 20 to 200 µl. P20 are useful for volumes from 0.5 to 20 µl. For beginners fixed volume pipetmen are more useful. It is important to ascertain whether the correct pipetman is chosen for measuring the volume one needs.

Abstract

Current trend of global agricultural systems entails preference towards sustainable crop production through organic agriculture (ecology based) as compared to conventional (synthetic input based). In order to claim as organic, it needs to be certified as per requirements organic standard. The soil fertility management organic standard requirements of major countries are outlined. This review article compares the agricultural management practices of organic and conventional systems so as to assess its impacts on microbial biodiversity, microbial activities on soil functioning and long term fertility based on long term field studies conducted in different parts of the globe.

Introduction

Plants possess complex, systematic and specific mechanisms to cope up with abiotic as well as biotic stresses in the existing environment. ‘Do plants respond to sound ? How can plants perceive sound without a hearing organ?’- are interesting queries among the scientific community. Responses of plants to different factors such as temperature, moisture, light, wind, pests and microbes are well understood. However, information on the effects of audible sound frequencies on plants are still lacking. Recent evidences suggest that audible sound stimulation can contribute to better plant growth and improved quality of plant produce. It also represents a new trigger for plant protection. Sound is an acoustic energy in the form of a mechanical wave which transmits through gases, liquids and solids. Acoustic spectrum consists of three regions, infra sound (less than 20 Hz), audible region (20-20,000 Hz) and ultrasound (greater than 20,000 Hz). Infra sound and ultrasound are used in clinical diagnosis and therapeutics.

Research on plant responses towards different stimuli started during 1880s by Charles Darwin. In 1848, Dr. Gustav Theodor Fechner, a German experimental psychologist, suggested that plants are capable of feeling emotions and that one could promote healthy growth of plants with talk, attention, attitude and affection. Later, J. C. Bose (1926), famous Indian botanist and physicist, made several studies on the effect of sound vibrations on plants. According to him, a plant treated with care and affection gives out a different vibration than a plant subjected to torture. In addition, Bose found that plants grew more quickly in pleasant music and more slowly in loud noise or harsh sounds. He also noticed that plants can “feel pain and understand affection” based on variation of cell membrane potential under different sound frequencies. Retallack (1973) also described several experiments involving plants and music.

The term rare amino acid is misleading in some respects. It refers to all those amino acids that are not incorporated into proteins. We already got to know some of them like ornithine or citrulline that are rather common intermediates of the basic metabolism. Roughly 220 different structures are known, most of which occur in plant cells in a free state though glutamate-, oxalate- or acetyl- derivatives can also sometimes be found.

Introduction

Plant architecture is defined as a three-dimensional organization of plant body in terms of its size, shape position of leaves, flower organs and branching pattern. Earlier this was the only criterion for systematic and taxonomic classification of plant species and the best means of identifying them (Stecconi, 2006). Study of plant architecture emerged as a new scientific discipline some 30 years ago. The subject derives its base from earlier works on plant morphology (Halle and Oldeman, 1970) but currently it is integrated with several disciplines of plant sciences ecology and engineering. Modification in plant architecture causes alteration in primary and secondary growth. This occurs due to differences in phyllotactic arrangement, branching pattern and floral differentiation. Plant architecture can be modulated by various parameters like climate, agronomic practices and human interventions. Manipulation of plant architecture is a major area in plant science which is currently adopted for productivity improvement by breeders, agronomists, horticulturists and landscape managers. However, the basis for such manipulation lies in the knowledge of the basic architecture of plants and its significance.

Definition

Based on various standard sources, plant breeding has been defined in various ways. A few important and standard definitions are:

The art and science of changing plants genetically.

Plant breeding is the genetic adjustment of plants to the service of man.

Improvement of crop plants as the result of process of evolution directed by man for his own ends. The basic principles of plant breeding are thus the principles of evolution. Directed evolution as imposed in plant breeding differs from natural evolution chiefly in a greatly reduced time-scale, and in a more precise control over the factors which govern hybridization and selection.

The science and art of manipulating the heredity of plants for a specific purpose.

Plant breeding is a deliberate effort by human to nudge nature, with respect to the heredity of plants, to an advantage. The changes made in plants are permanent and heritable and the professionals who carry out this task are called plant breeders. This effort at adjusting the status quo is instigated by a desire of humans to improve certain aspects of plants to perform new roles or enhance existing ones. As a result, the term “plant breeding” is often used synonymously with “plant improvement” in recent years. Normally the term plant breeding connotes the involvement of sexual process in effecting a desired change; however, it is also true that modern plant breeding also includes the manipulation of asexually reproducing plants (plants that do not reproduce through the sexual process). Breeding is therefore about manipulating plant attributes, structure, and composition, to make them more useful to humans.

Gepts and Hanock (2006) have defined plant breeding as an applied, multidisciplinary science. It is the application of genetic principles and practices associated with the development of cultivars more suited to the needs of human than the ability to survive in the wild; it uses knowledge from agronomy, botany, genetics, physiology, pathology, entomology, biochemistry and statistics. Of particular importance is the ability to transfer, in addition to major genes, large suites of genes conditioning quantitative traits such as productivity and other traits of interest to humans. The ultimate outcome of plant breeding is mainly improved cultivars. Therefore, plant breeding is primarily an organismal science even though it is eminently suited to translate information at molecular level (DNA sequences, protein products) into economically important phenotypes. The traditional definition of plant breeding includes only those scientists who develop new cultivars and improved germplasm, however, many feel this definition should be expanded to include scientists who contribute to crop improvement through breeding research.

Plant breeding is the art and science of changing and improving the heredity of plants. The art of plant breeding lies in the breeder’s skill in observing and selection of superior plants. The value of selection largely depends upon the skill of the breeder. The skill that a breeder develops though a close and deep study of the concerned crop species. Before the rediscovery of the Mendelian Laws in 1900 AD, the plant breeding is as an art. The modern age of plant breeding began in the early part of the twentieth century, after Mendel’s work was rediscovered. Today plant breeding is a specialized technology based on genetics. It is now clearly understood that within a given environment, crop improvement has to be achieved through superior heredity. Plant breeding developed into a science as knowledge progressed towards the genetics, cytogenetic, physiology, pathology, biochemistry, biotechnology and biometry. The fundamental of plant breeding was based on recognition of the genes. The genes were identified by their effects on the visible expression of plant traits such as whether a plant was a dwarf or tall, or the flower color was white or pink. Through systematic hybridization, a desirable gene could be transferred from one to another cultivar. More recently the science of molecular genetics proposes to advance plant breeding. Molecular genetics was ushered in with the description of chemical structure of deoxy-ribonucleic acid (DNA), the material that constitutes the genes. DNA carries the instructions for synthesis of specific proteins that determine the visible expression of particular characters. The new technology does not supplant nor diminish the importance or need for traditional selection and crossing procedures in the breeding of improved cultivars. The performance of today’s cultivars reached at high levels through refined selection and hybridization breeding procedure.

The early developments in plant breeding that took place are based on archaeological evidence. The first efforts to grow wild plants probably occurred in Southeast Asia culminated in the domestication of some of the many plants with which humans experimented in 13000 BC. By 10000 BC, advanced knowledge existed of such plants as rice (Oryza sativa), several legumes such as pea (Pisum sativum), runner bean or broad bean (Phaseolus or Vicia spp.) and possibly soybean (Glycine max). At this point crops became domesticated.

Although the beginning of civilization in China and Southeast Asia are obscure and fragmented. The number of successful species domesticated indicates considerable success in plant breeding. The third site of independent agricultural development and plant breeding was in south-central Mexico between 6700 and 5000 BC. Squash and avocados were domesticated first and a number of species of maize. Domestication in the Middle East and China included the self-fertilized crop like cereals and soybean.

Systematic scientific efforts to improve genetic potential of crops in India were initiated in 1905 at the Imperial/Indian Agricultural Research Institute. In 1929, with the establishment of the Indian Council of Agricultural Research (ICAR), several associated developments took place in the first half of the 20th century leading to establishment of several crop-based institutes (sugarcane, cotton, jute, rice, oilseeds, tobacco, potato) and multidisciplinary institutes such as the Indian Agricultural Research Institute (IARI), Central Arid Zone Research Institute (CAZRI), and Central Plantation Crops Research Institute (CPCRI). Additionally, a Project on Intensification of Regional Research in Cotton, Oilseeds and Millets (PIRRCOM) was implemented during 1950s with establishment of several research stations in different regions.

Broadly and conceptually breeding methods can be classified into four groups. These are:

• Selection breeding
• Combination breeding
• Hybrid breeding
• Special breeding techniques

There are fluid transitions and similarities between the individual groups of breeding methods. Selection not only takes place in the group termed selection breeding but also in other groups. In breeding varieties by combination, new variation is generated by crossing genetically different parents followed by application of various selection methods and ultimately development of a new recombinant type pure-line. In hybrid breeding, inbred lines of different genetic constitution are produced by selfing, pair crossing and other methods and from these best lines are selected and new hybrids are developed. In addition, breeding methods can also be classified according to other criteria. For example, breeding methods have also been classified according to the manner of propagation of the varieties. These are:

Summary

This review addresses various defense strategies evolved by plants to resist pathogen attack.Of the different defensive strategies, pathogen attack either induces or enhances constitutively the synthesis of a spectrum of diverse chemical compounds in various plant species. These chemical compounds also called secondary metabolites are classified broadly as nitrogen compounds, terpenoids and phenolics and have been documented to possess broad range antifungal, antimicrobial and pesticidal activities. Such defensive compounds could be extracted and developed as eco-friendly biopesticides/microbicides because of their natural occurrence, ephemeral nature and biodegradability. These will be favorable alternative strategies compared to chemical pesticides that are fraught with various harmful side effects.

Biodiversity is the foundation stone of human survival on the earth. Very appropriately, the theme of the World Food Day celebration, 16 October, 2004 was “Biodiversity for Food Security” Biological diversity is fundamental to agriculture and food production. Scientists have identified so far about 1.4 million of the plant and animal species that exist on earth. A rich variety of cultivated plants and animals serves as the foundation for agricultural biodiversity. Yet people depend on just 14 mammal and bird species for 90 % of their food supply from animals. Just four plant species, namely, wheat, maize, rice and potato provide half of our energy from plants (FAO, 2004).

India is located between 8^°- 38^° N and 68^°- 97^ºE and exhibits extreme variation in altitude — from sea level to heights above vegetational limits in the Himalayas (ca 4500 m), and climate — from monsoon- tropical in south to temperate and alpine in the north-western Himalayas and extremely arid to semi-arid in the north-western plains. It is floristically extremely rich with about 33 percent of its botanical wealth (over 15,000 species of higher plants) being endemic. There are about 141 endemic genera distributed over 47 families. Further, of the 4,900 endemic species, larger percentage is localised in the Himalayas (about 2,532 species) than in other regions, namely, the peninsular tract (1,788 species), and the Andaman and Nicobar Islands (185 species). It is also estimated that floristic richness is maximum in the north-eastern region, which holds about 50 percent of India’s total species diversity, i.e., more than 7,000 species, and is considered as the cradle of flowering plants. Of 990 species of orchids, 700 species occur in this region (Nayar, 1989). This, thus, makes the Indian region botanically unique and interesting (Arora, 1991).