eChapters

Abstract

The present studies were undertaken in selfed and open pollinated seedlings of 11 cultivars namely Belrubi, Blackmore, Catskill, Chandler, Fairfax,  Fern, Pajaro, Seascape, Selva, Tioga and Torrey during the years 2001 to 2003.  The days taken to 50%  flowering varied  from 43 to 64 days, flower number from 11.8 to 22.4 and pollen viability from 77.5 to 85.2%. The pollen germination was highest in 20% sucrose solution +  5 ppm boric acid in all the progenies.  The fruit length varied from 27.8 mm to 35.5 mm, breadth 21.3 to 27.9 mm, fruit weight 8.8 to 12.2 g, fruit firmness 0.23 to 0.33 lbs force, number of achenes per fruit 176.9 to 297.9, pedicel length 6.4 to 9.5 cm, TSS 8.1 to 12.3^ºB, titratable acidity 0.58 to 1.24%, total sugars 5.1 to 7.3, reducing  sugars 4.8 to 6.8% and non-reducing sugars from 0.50 to 1.11%.  Fruit development period  varied from 32.8 to 53.6 days, total number of fruits per plant 7.2 to 17.9, fruit yield per plant 27.4 to 57.3 g and fruit yield per plot from 0.77 to 1.40 Kg in different progenies.

1. Introduction

Spices are a high-value, low-volume commodity traded around the world. Spices have played a significant part in civilisation, exploration, and commerce throughout history. Since ancient times, India has been known as the spice capital of the world, with over a hundred different types of spices grown. India has long been a traditional producer, consumer, and exporter of spices, with nearly every state producing one or more of them. India has a total area under spice production of 39,27,430 ha, which produced 95,99,900 MT in 2017-18. (Spices Board, 2020a). Due to their rich aroma, texture, and flavour, Indian spices are in high demand around the world.

Introduction

Soil is a dynamic natural body, characterized by high degree of spatial variability due to combined effect of physical, chemical or biological processes that operate with different intensities at different scales (Goovaerts 1998). Reports have shown that there is large variability in soil properties, crop yield, disease, weed etc., not only in large-sized fields (Godwin and Miller 2003,Vrindts et al. 2005), but also in small-sized fields (Bhattacharya et al. 2008). Therefore, knowledge of hydro-physical properties of soils is crucial for management practices for all kinds of agricultural practices for efficient utilization of input resources. Plant growth and development is highly related to soil hydro-physical properties, which not only depend on soil intrinsic textural and chemical characteristics (Hamza and Anderson 2005) but also on soil management.

Soil physical properties which change with the variation in soil structure include bulk density, total porosity, pore geometry (size distribution, shape, continuity and tortuosity), penetration resistance and aggregate stability, consequently affecting soil hydraulic properties such as water retention characteristics, plant available water capacity, infiltration capacity and saturated hydraulic conductivity. These soil properties are dependent on seasonal climatic conditions, management practices, crop development and biological activity (Reynolds et al. 2007). The hydro-physical properties of soils, i.e., water retention and water permeability in both saturated and unsaturated zones not only shape soil water balance but also decide the conditions for plant growth, development and yield. They also determine water availability for the plant root system and the transfer of water with chemical compounds dissolved in it into deeper layers.

Knowledge on genetic variability of the available population is very essential for any crop improvement programme, as it will positively enhance the efficiency of selection. The variability in quantitative characters increase considerably by treating the biological materials with different mutagenic agents. It is possible to identify mutants for different characteristics which can be useful in further programme. Variability is measured by different statistics viz., phenotypic coefficient of variation (PCV) and genotypic co-efficient of variation (GCV). GCV would be more useful for the assessment of inherent variability as it exhibits the heritable portion only.

Abstract

Considerable variation for different metric and non-metric characters was observed in seedling population of Pistachionut. The variation for non-metric characters was observed for precocity in flowering, colour of the kernel, shelling and splitting percentage. The studies have resulted in the identification of two pistillate and three staminate trees with desirable traits which can be exploited in breeding programme or used as elite planting material.

Abstract

Ten genotypes of Cenchrus ciliaris L. were evaluated for seed yield and its components under arid environment prevailing at Jodhpur. The genotypes were grown (using seeds) during July 2010 and three cuts of fodder were taken up to November, thereafter allowed to produce seeds. Fodder of re-growth was finally harvested in June 2011 after seed collection. Analysis of variance showed significant variation among the genotypes for all the characters studied, viz.

Minisatellite is a section of DNA that consists of a short series of bases 10– 60bp. These occur at more than 1000 locations in the human genome. Some minisatellites contain a central (or “core”) sequence of letters “GGGCAGGANG” (where N can be any base) or more generally a strand bias with purines (Adenosine (A) and Guanine (G)) on one strand and pyrimidines (Cytosine (C) and Thymine (T)) on the other. It has been proposed that this sequence per se encourages chromosomes to swap DNA. In alternative models, it is the presence of a neighbouring cis-acting meiotic double-strand break hotspot which is the primary cause of minisatellite repeat copy number variations. Somatic changes are suggested to result from replication difficulties (which might include replication slippage, among other phenomena). When such events occur, mistakes are made, this causes minisatellites at over 1000 locations in a persons genome to have slightly different numbers of repeats, thereby making them unique. The most highly mutable minisatellite locus described so far is CEB1 (D2S90) described by Vergnaud.

Variable is any character or attribute of the given object/set of objects which varies from object to object or from one point of time to another point of time. For example height of individuals is a variable; it varies from person to person.  Kerlinger (1973) defined variable as a symbol to which numerals or values are assigned.

Importance of variables: In previous sections, we discussed about formulating the research problem and development of research hypothesis. Variables are the building blocks of any scientific research problem and research hypothesis. When we consider a hypothesis to be relational hypothesis, we mean that it make claims about relationship between two or more variables. When we test hypothesis, as such we do not test the hypothesis, rather we test the significance of hypothesised relationship between two or more variables. Since variables play central role in observation, measurement and testing of relationship, it is of prime importance to understand the meaning of variables, different types and the way we define these variables.

Biometrical Genetics - Historical Background

It is a science built on the principles of Mendelian genetics and the way in which the genetic factors influence the statistical properties of traits in families and populations. The roots of biometrical genetics go back to Gregor Mendel, who first demonstrated the existence of the hereditary factors and to Francis Galton who first applied statistical methods to study biological inheritance. Galton introduced the concepts of regression and correlation for studying the continuous variation in humans, but was not aware of the principles of genetics discovered by Mendel. Galton, Karl Pearson and Walter Weldon together started the journal Biometrika in 1901, with the aim of promoting the statistical studies in biological phenomena. The differences of opinion persisted between the Biometricians and Mendelians in the early 20th Century. In 1918 Ronald A. Fisher published a landmark paper ‘The correlation between relatives on the supposition of Mendelian inheritance, in which he showed the two seemingly contradictory approaches could be reconciled in terms of a simple biometrical genetic model. Ronald A. Fisher’s paper laid the foundation for the discipline of Biometrical Genetics.

Foundation

a) Mendelian Inheritance

Mendel proposed three principles based on his work and now known as Mendel’s laws of inheritance

• Law of uniformity: if two homozygote parents of different alleles cross together, all offspring must have the same genotype

• Law of segregation: an individual receives with the equal probability one of the two genes from the genotype of the mother and similarly from that of the father.

• Law of independent assortment: the segregation of the genes for one trait is independent of the segregation of genes for other traits in the formation of reproductive cells

In association studies, the law of segregation is the basis for the transmission disequilibrium test (TDT). The possible violation of law of independent assortment forms the basis of the gene mapping technique, linkage analysis. These principles are used to check the quality of parent-offspring genetic data. Mendelian principles though developed for dichotomous traits, they can be applied to the inheritance of traits influenced by multiple genes and are fundamental to genetic analysis.

The amount of variation is measured and expressed as the variance. When values are expressed as deviations from the population mean the variance is simple the mean of the squared values. For example, the genotypic variance is the variance of genotypic values and the environmental variance is the variance of environmental deviations. The total variance is the phenotypic variance of the variance of phenotypic values, and is the sum of the separate components. 

Variation in Chromosome Structure

Natural variation exists in chromosome structure

Changes in chromosome structure include deletions, duplications, inversions, and translocations

The loss of genetic material in a deletion tends to be detrimental to an organism

Duplications tend to be less harmful than deletions

Duplications provide additional material for gene evolution, sometimes leading to the formation of gene families

Copy number variation is relatively common among members of the same species

Comparative genomic hybridization is used to detect chromosome deletions and duplications

Inversions often occur without phenotypic consequences

Inversion heterozygotes may produce abnormal chromosomes due to crossing over

Translocations involve exchanges between different chromosomes

Individuals with reciprocal translocations may produce abnormal gametes due to the segregation of chromosomes

Introduction

Understanding the variation in grain protein content is the pre-requisite of its improvement in modern rice varieties. The measure of quantitative and qualitative aspects of grain storage protein content includes estimation of soluble and total grain protein, quantifying various fractions, viz. glutelins, prolamins, globulins and albumins and their profiling through SDS-Page and  estimation of amino acid. As traditional chemical methods for protein content determination are destructive in nature. All these estimates comprehensively give insight into the diversity of storage protein in rice germplasm. The standard procedures followed for all these estimates are briefly stated in the  following sections.

Estimation of Total Grain Protein Content in Rice

The total protein is estimated via estimation of total N through the Kjeldahl method whereas soluble protein is estimated through Lowry method, Dumas method and Bradford method. But for estimation of large number of genotypes all these processes are tedious, time-consuming, and costly. Near-infrared spectroscopy (NIRS), as a non-destructive detection technique, can achieve rapid quantitative determination of protein contents and become an important development direction to replace traditional chemical detection methods.

INTRODUCTION

Variability in different organisms is common feature and is an important process for the continuity of life under stress conditions. Plant pathogens especially fungi, bacteria, virus and nematode show variations in their pathogenic potential (virulence) and physiological functions that support their survival and perpetuation in different environmental conditions. These variations may be largely due to genetic factors that may be conditioned by environmental factors. Various studies on genetic variability of microbial plant pathogens have shown that variations may occur in characters which affect their ability to infect host plants and also other characters that do not alter the pathogenic potential, but they may be concerned with their survival. Knowledge of variation in pathogenic characteristics is valuable in planning effective measures for disease management. In addition, development of resistant to fungicides has been a serious concern to growers, researchers as well as the administrators, since the decision to continue application or withdrawal of a fungicide can affect both the growers and industry.

10.1 Introduction

Plant breeders come across two categories of characters (traits) for improvement, namely, qualitative characters and quantitative characters. Red vs white flower, round vs wrinkled seed, determinate plant growth vs indeterminate plant growth etc. are examples of qualitative trait differences. There is no overlapping of characters and no confusion during classification. Such trait differences are usually governed by one or two gene pairs, each with large effect that can be measured even in the presence of segregation at other loci and even in the presence of effects of environmental factors. These characters are very less influenced by the environmental factors.

On the other hand, most of the traits of economic importance like yield of fruits of vegetable and fruit crops, yield of vegetative parts in fodder crops, yield of lint in cotton, yield of grains in cereals, pulses, oilseeds etc., plant height, days to maturity etc. are examples of quantitative characters. Variation observed for such traits is continuous. Again, there is overlapping of trait differences. So, one cannot assign individuals to a specific class unambiguously. Such characters are influenced by environmental factors, such that phenotypes are not same when grown over locations and/or seasons.

When different plants/lines of a species exhibit trait differences, it is called variation. Variation is essential for any improvement in a crop. It may be present in the population to be improved or else it may be created by different means such as hybridization, mutation, polyploidy, domestication, plant introduction, somaclonal variation, genetic engineering etc. Now, we shall discuss the types and estimation of variation.

As the blood returns to the heart it passes through special thin walled vessels called veins. Unlike the tough strong arteries, these vessels are easily distended. One can demonstrate by pressing the finger on a vein on the back of hand and watching it swell as the blood builds up behind it. Blood flowing from the head and upper chest flows downward toward the heart. On the other hand, blood coming from the lower extremities must flow upward. To make this possible nature has provided valves in the veins so that the blood can flow only toward the heart, never in the other direction.

In human beings there are two sets of veins. The deeper veins are located within the muscles where they are given good support. But the veins on the surface just under the skin have little support and are easily damaged. These surface veins are often subject to inflammation or phlebitis.

In some people the veins in the legs are weak and may swell easily. Varicose veins, seems to run in families. Anything that increases the pressure in the pelvis or abdomen may slow the flow of blood back to the heart from the lower extremities. One frequent cause of varicose veins is pregnancy; other is obesity. Anything that increases the pressure within the veins of the legs and thighs may weaken or break down the little valves, so that the veins become enlarged and the blood does not finds its way back to the heart as it should.

When a variety is grown under different environmental conditions, phenotype is the result of genotype+environment+genotype×environment interaction. Genotype×environment refers to the interaction effect of the genotype with different environments. Presence of this interaction leads to overestimation of genetical and biometrical parameters and thus may yield misleading results. This interaction also influences the varietal adaptation of new improved genotypes. Adaptation refers to certain varietal features (morphological and physiological) which promote survival under that environment. In production and breeding programmes adaptability is related to economic yield i.e. genotypes producing higher economic yield under different environmental conditions are comparatively more adaptive than those which produce low yield. Varietal adaptability refers to the capability of a genotype to grow normally and perform well in an environment or different environments. Adaptation of genotypes depends upon certain characters i.e. both morphological and physiological which promote survival under an environment. In natural conditions adaptation is brought by natural selection, but in artificial breeding, adaptation is induced by the breeders.