eChapters

Abstract

The present investigation was carried out in okra consisting of 11 diverse genotypes (8 lines & 3 testers) and their 24 F1 hybrids. Phenotypic and genotypic correlation indicated positive association of average fruit length with average fruit weight while negative association between days taken to first flower with number of fruits per plant. The maximum positive direct effect on yield was due to number of fruits per plant followed by average fruit weight. The F₁ hybrid VRO-6 × Parbhani Kranti exhibits highest negative heterobeltiosis for days taken to 1^st flowering while D-1-87-5 × Pusa A-4 and Arka Abhay × Parbhani Kranti are earliest heterobeltiotic hybrids for days taken to 1st harvest. The hybrid Arka Abhay × Pusa A-4 represents highest heterobeltiosis for average fruit length, number of fruits/ plant and average yield. Among all parents, only Akra Abhay exhibits better GCA effect. The highest SCA effect for average yield observed in VRO-6 × Arka Anamika, while VRO-6 × Pusa A-4 for per cent infestation of YVMV. The cross Arka Abhay × Pusa A-4 incurred the highest net returns/ ha and B: C ratio (3.21) followed by that of D-1-87-5 × Parbhani Kranti and the parent Hisar Unnat gave the higher net returns/ ha with B: C ratio of 2.02 among the parents. These elite hybrids may be tested for yield and other quality traits under different agro-climatic conditions for commercial exploitation of hybrid vigour.

Abstract

Spot blotch of wheat is devastating disease as one of the yield limiting factor especially in north eastern plains zone and also in north western plains zone of India. Chemical fungicides play an important role in controlling the spot blotch in India due to non availability of spot blotch resistant commercial varieties. To identify the suitable chemicals method and time of application, various fungicides thiram 37.5% WP, carboxin 37.5% WP +, propiconazole 25% EC, tebuconazole 25% EC and mancozeb 75% WP) were evaluated either as seed treatment or foliar sprays or in combination under artificial epiphytotic in vivo conditions for two crop seasons. Seed treatment (ST) by thiram + carboxin @ 2.5 g/kg of seed along with Foliar spray (FS) of propiconazole @ 0.1% at boot leaf stage on Flag-1 leaf followed by second spray at 20 days interval (two sprays) resulted in best management of spot blotch in severe conditions. It was found that the fungicide treatment not only reduced the spot blotch disease but also increases the grain yield.

Abstract

A field experiment was carried out during rabi 2012-13 at Bihar Agricultural College farm, Sabour, Bhagalpur to assess the effect of different herbicides on microbial population dynamics of soil in winter maize (Zea mays L.). The experiment comprised of ten weed management treatments involving various herbicides (acetochlor @ 1.125, 2.25 and 4.5 kg a.i. ha^-1, atrazine @ 1.0 kg a.i. ha^-1, pendimethalin @ 0.5 kg a.i. ha^-1 + atrazine @ 0.5 kg a.i. ha^-1, alachlor @ 0.5 kg a.i. ha^-1 as pre-emergence and 2,4-Diethyl ester @ 0.6 kg a.i. ha^-1and topramezone @ 0.04 kg a.i. ha^-1+ atrazine @ 0.25 kg a.i. ha^-1 as post-emergence including weed free and weedy check laid in randomized block design with three replications. Results indicated that all the herbicides’ treatment showed significant adverse effect on microbial population in rhizospheric soil of winter maize up to 45 days after sowing. Further, there was reduction in soil microbial population occurred in all the herbicides treated plots up to said time period as compared with weed free and weedy check. Initially the soil microbial population in weed free plot was much higher than that of weedy check, however, it was found in reverse trends in rest of the time intervals as well as harvest. Thereafter, soil microbial population was gradually increasing at different time intervals and at harvest, their population increased considerably in herbicidal treated plots though the weed free and weedy check showed higher soil microbial population than other herbicide treated plots.

Abstract

Lentil (Lens culinaris Medik) is an important rabi leguminous annual herb with rich source of protein and other balanced nutrition. Lentil is susceptible to many insect-pests and diseases which causes significant yield loss which may range from 50 to 100% leading to one of the most important biotic constraints in productivity. The major fungal diseases in lentil are Fusarium wilt, Ascochyta blight and rust which causes severe losses in lentil production. Other minor diseases like botrytis grey mould, anthracnose, alternaria, stem rot, collar rot and some viral diseases also infect the lentil field under condusive environment conditions. Coming to major insect pests of lentil viz. helicoverpa, aphids, leaf weevils and lygus bugs with several noteworthy minor field pests such as thrips and cutworm with few storage pests that infest the crop. With an integrated blueprint of disease management, one can minimize risk of yield loss by following modified package and practices with need based use of pesticides, thus maximizing profit in lentil production.

Abstract

Mungbean [Vigna radiata (L.) Wilczek] is an important pulse crop grown in India. It is a short duration annual with yellow flowers and fuzzy brown pods. Majority of the mungbean grown in India is under rainfed conditions and the productivity of mungbean is not upto the mark to meet the daily dietary requirement of a populous country like India. The biotic and abiotic stresses in mungbean, majorly MYMV, powdery mildew, drought, salinity, water logging etc leaves a severe yield loss in mungbean crop. Among them, MYMV and powdery mildew diseases show yield losses accounting upto 85% and 40%, respectively in severe conditions. The present review paper is based on the study of both biotic and abiotic stresses and the recent advances in breeding for resistance to stresses. A detail explanation of major diseases and insect pests affecting mungbean are discussed along with the information of genomic resources and research done in mungbean in recent years. Recently SSR’s have been using widely for all molecular level research work like genetic diversity, constructing linkage maps for identifying QTL’s, marker assisted breeding etc. in mungbean. The resistant varieties developed against these biotic and abiotic stresses are listed which are very important for attaining a prominent yield in mungbean.

Abstract

The major losses of banana at present by Panama wilt disease pathogen of banana and its management is very typical because it is caused by a soil-borne pathogen (Fusarium oxysporum f.sp. c u b e n s e ). The micronutrients are used to manage the disease as well as it provides the healthiness of plant and increases the fertility of the soil that’s why the plant is free from the disease or less infected. An experiment of micronutrients was conducted in the laboratory of plant pathology BAU, Sabour for Invitro evaluation of the micronutrients viz. Zinc Sulfate, Ferrous Sulfate, Ammonium Sulfate, Copper Sulfate, Calcium Nitrate, Borax and Potassium Chloride against Fusarium oxysporum f.sp. cubense causing Panama wilt of banana. The results of the experiment revealed that among the micronutrients used, Borax @ 500 and 750 ppm completely inhibited the mycelial growth of FOC followed by Zinc Sulfate (45.7, 42.6, 39.2 and 18.5 mm at 100, 250, 500 and 750 ppm respectively). The incorporation of borax in the solid medium at higher concentrations viz., 500 and 750 ppm is very effective for the management of Panama wilt disease of banana. This approach leads to maintain our ecosystem sustainability for a longer time and manage the disease.

Abstract

Chickpea is one of the major grain legume crops of the tropics and subtropics. It is the second most important pulse crop after pigeon pea in India and is commonly known as gram or Bengal gram is a versatile crop among the grain legumes with a total production of 11.6 (Mt) from 13.2m ha. However, it ranks fifth in the productivity after Fababean, pea, lupin, and lentil and ranks first among the pulses both in acreage and production. Whereas, area under pigeon pea 3.90 mha with a total production and productivity of 2.89 mt and 741 kg/ha, respectively and is commonly known as red gram or Arhar is a very old crop of India. The chromosome number of pigeon pea is 2n = 22 chromosomes. They are the rich source of protein and supplies a major share of the protein requirement of the vegetarian population of the country. Chickpea accounts for 70.7% of the world Chickpea production n India followed by Australia, Pakistan, Turkey, Myanmar, Ethiopia, Iran USA, Canada and Mexico. Both crops are used as an important source of protein in human nutrition and cattle feed. Chickpea is considered to have medicinal effects and it is used for blood purification. Chickpea contains 21% protein, 61.5% carbohydrate, 4.5% fat. Its seed is also rich in protein, starch, fiber, calcium, iron and niacin, malic and oxalic acid, which makes it one of the best nutritionally balanced pulses for human consumption. However, like any other pulses, the chickpea seed also contains antinutrional factors, which can be reduced or eliminated by cooking. Both crops enrich the soil fertility by fixing atmospheric nitrogen in the root nodules and improve the soil structure. It is also to improve soil fertility by biological nitrogen fixation which helps reduce the input cost for the existing crop. These crops usually receive few inputs other than labor, insecticides and seed. Chickpea is a crop of both tropical and temperate regions. Low yield of chickpea attributed to its susceptibility to several fungal, bacterial and viral diseases. In general, estimates of yield losses by individual insects and diseases range from 5 to 10% in temperate regions and 50 to 100% in tropical regions. Whereas, Pigeon pea can be attacked by more than 100 pathogens. These include fungi, bacteria, viruses, nematodes, and mycoplasma like organisms. Fortunately, only a few of them cause economic losses and the distribution of the most important diseases is geographically restricted. The diseases of considerable economic importance at present are Fusarium wilt, sterility mosaic, phytopthera blight and alternaria blight.

Abstract

Fusarium wilt is major disease in Central India, the major lentil growing region of country. The disease is soil borne causing heavy loss, development of wilt resistant varieties is most effective means of controlling this disease. Highly resistant sources of wilt in lentil have not been reported from the Indian lentil breeding programme. One hundred thirty lentil genotypes including one susceptible check were evaluated in control conditions of green house against wilt, based on controlled condition screening- LL 1370, IPL 333, PL4, RLG 195, RVL 14-4, L 4737, RKL 607-1, WBL 77, LL 1320, LL 1397, VL 525, LL1379, VL526, RVL14-5, L4717, VL126, L4076, RLG191 and VL150 have been identified as highly resistant genotypes. These can be used in hybridization programme for wilt resistance breeding and studying the inheritance of wilt resistance in lentil.

Abstract

Lentil is an important pulse crop and play very important role in the supply of the protein to under nourished vegetarian population of the country. Fusarium wilt of lentil caused by Fusarium oxysporum f. sp. lentis is one of the wide spread and destructive diseases in India under rice-based cropping system. Use of synthetic fungicides has led to the emergence of several problems like environment pollution, residual effect in grains and killing of non-target organism(s). Hence, for minimizing the losses caused by Fusarium wilt, four plant extracts such as Garlic, Neem, Eucalyptus, Tulsi and three antagonistic bio-agents viz. Trichoderma viride, Trichoderma harzianum and Pseudomonas fluorescence were evaluated in vitro. The results clearly showed that all plant extracts were more or less inhibitory to mycelial growth of Fusarium oxysporum f. sp. lentis. The effectiveness of extracts increased with increase of their concentration and maximum growth inhibition was obtained in Eucalyptus followed by Garlic and Tulsi. While minimum per cent inhibition was recorded in Neem. Among bio-agents, T. viride showed maximum growth inhibition of Fusarium oxysporum f. sp. lentis followed by T. harzianum at both 4 and 7 days incubation period.

Abstract

Pigeon pea is an important pulse crop of India and its production is greatly affected by wilt disease. Pigeon pea wilt is a very destructive soil borne disease caused by Fusarium udum. In present research work plant extracts (Garlic, Neem, Tulsi), bio-agents (Trichoderma viride and Pseudomonas fluorescens) and fungicides (Vitavax, Bavistin and Thiram + Carbendazim) were tested against Fusarium udum. Among them fungicides were found most effective in inhibiting mycelial growth of Fusarium udum recorded 100% inhibition followed by garlic bulb extract (52.12 to 56.33%). Among bioagents, Pseudomonas fluorescens inhibit the growth up to (46.00 to 51.79%) followed by T. viride (44.32 to 48.79%) amongst all treatments except untreated.

Keywords: Pigeon pea, Fusarium udum, bio-agent, fungicide

Pigeon pea (Cajanus cajan L. Millsp.) is one of the major pulse crops grown in the tropics and subtropics belonging to family Leguminaceae. It has wide adaptability and low input requirements mostly grown in kharif season.

Abstract

Pigeonpea (Cajanus cajan) is an important pulse crop of India and its production is greatly affected by wilt disease. Pigeonpea wilt is a very destructive soil borne disease caused by Fusarium udum. In the experiments, ten treatments were applied viz.; Neem leaf extracts (T₁), Garlic extracts (T₂), Tulsi leaf extracts (T₃), bio-agents Trichoderma viride (T₄), Pseudomonas fluorescens (T₅), Polymer coating (polycot) @ 4 ml diluted in 5 ml of water per kg of seed (T₆), Polymer coaating + Trichoderma viride @ 6.0 g per kg seed (T₇), Polymer + Pseudomonas fluorescens @ 6.0 g per kg seed (T₈), Polymer coating (polycot) 4 ml diluted in 5 ml of water per kg seed + Vitavax power @ 3g per kg seed (T₉) and T₁₀ served as untreated. The observations were recorded six times at 10 days intervals and started from 40 days. These polymer alone @ 4.0ml per kg and in combination with bioagents and fungicides were applied to seed were tested against Fusarium udum. The highest per cent disease control and per cent wilt disease incidence were recorded 96.09 to 64.09 and 2.74 to 33.32, respectively in T₉ (Polymer + Vitavax power @ 3g per kg seed) at 10 days intervals followed by T₈ (Polymer + P. fluorescens) gave 94.46 to 53.06 per cent inhibition, T₇ (92.39 to 52.74) and T₆ (90.97 to 49.73) however, the lowest per cent disease control was noticed as 76.19 to 40.13 per cent in T₁ (Neem leaves extract) amongst all treatments except untreated.

The concept of gene has undergone several refinements since its discovery in 1866 by Mendel. Most genes encode one polypeptide and can be operationally defined by the complementation test. The complementation or cis-trans test provides an operational definition of the gene. It is used to determine whether mutations are in the same gene or in different genes. Intragenic complementation may occur when a protein is a multimer containing at least two copies of one gene product. The concept of gene has evolved from a bead on a string, not divisible by recombination or mutation to a sequence of nucleotide pairs in DNA encoding one polypeptide chain. The unit of genetic material not divisible by recombination or mutation is the single nucleotide pair. Historically several experimental developments have occurred to facilitate understanding of the structure and function of gene and these are briefly described in a chronological order as follows to have better understanding of the gene concept as it evolved. However, before discussing evidences supporting various gene concepts, it is better to summarize important stages in the evolution of the gene concept.

Regulator Genes

Bacterial cells are capable of producing many kinds of enzymes in relatively large quantities but the kinds and amount of enzymes actually produced at any given time are usually those which are required at that particular time in response to the prevailing environment. Inducible enzymes are ordinarily absent or present in very small quantities until a specific compound appears. This compound is called as inducer. A typical example of this is production of b galactosidase (an enzyme that splits lactose into galactose and glucose, Fig. 44.1) once the lactose is introduced into the medium on which E. coli cells are grown. Here lactose acts as inducer for the enzyme b galactosidase.

Biochemical reactions are mediated by enzymes and all enzymes are proteins. Proteins are polymers of subunits (monomers) called amino acids which are often termed as ‘residues’. Each amino acid has an amino group (NH ) at one end and a carboxyl group (COOH) at the opposite end. 20 different kinds of amino acids occur naturally in proteins. Each enzyme consists of a certain number of amino acids in a precisely ordered sequence. The blueprint for making proteins is coded in the nucleotide sequence of DNA. The number of nucleotides which code for an amino acid is termed a codon. There are 20 common amino acids but only four different nucleotides. Obviously a singlet code (one nucleotide coding for one amino acid) could code only for four amino acids. A coding sequence of two nucleotides for one amino acid or a doublet code would produce 4₂ = 16 possible coding combinations or codons and this arrangement is not sufficient to take care of 20 amino acids. A codon size of three nucleotides for one amino acid or triplet code seems more likely as it produces 4₃ = 64 possible codons as illustrated in Table 43.1 (Strickberger, 1968).

In transcription, it has become clear as to how there is the transfer of genetic information stored in the sequence of nucleotides-pairs in DNA to the sequence of nucleotides in m-RNA molecules which carry that particular information from the nucleus to the sites of protein synthesis (ribosomes) in the cytoplasm. Further, there is the requirement of the process by which genetic information stored in the sequences of nucleotides in m-RNAs is used to specify the sequences of amino acids in the polypeptide gene products. This process known as translation takes place in the cytoplasm on complex workbenches called as ribosomes. With exception of water, proteins are by far the most prevalent component of living organisms in terms of total mass.

Proteins (= enzymes = genes) are composed of polypeptides and every polypeptide is encoded by a gene. Each polypeptide has a long sequence of amino acids linked together by covalent bonds. There are 20 different amino acids (glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan, cysteine, serine, threonine, tyrosine, asparagine, glutamine, aspartic acid, glutamic acid, lysine, arginine, and histidine) present in most proteins. All amino acids except proline contain a free amino group (NH₂) and a free carboxyl group (COOH) as illustrated below:

According to the central dogma of molecular biology, genetic information flows (i) from DNA to DNA during its transmission from generation to generation and (ii) from DNA to protein during its phenotypic expression in an organism (Fig. 41.1).

Watson and Crick based on their double helical DNA model, offered to explain DNA replication by a method where each single strand of DNA is template or mold for its complement and a new helix has one old strand and one newly synthesized strand. This type of DNA replication is called as semi-conservative as in this method one old strand is retained and one new complementary strand is synthesized. In contrast to semi-conservative mode of DNA replication, two more modes of DNA replication were proposed. One is conservative type where two new strands are synthesized in form of a double helix while the old double helix remains unchanged. The third type of DNA replication proposed has been dispersive mode of DNA replication which amounts to breaking down of double helical strands into small pieces along the length, their replication and random assemblage with newly synthesized pieces to form a patchwork single string of dispersed old and new pieces. These three modes of replication of DNA molecule are shown in Fig. 40.1.

The search for the chemical basis of genetic material began about one and half century ago. Soon after discovery of Mendelian principles of segregation and independent assortment in 1865, Friedrich Miescher (1844-1895) published a method for separating cell nuclei from the cytoplasm and from these cell nuclei, he extracted an acid material termed as “nuclein” which had unusually large amount of phosphorous. Miescher concluded that this substance was unique and was just not comparable with any other group known at that point of time. Later on nuclein, now named as “nucleic acid” was found to be associated with various proteins and the combined entities were termed as “nucleoproteins”.

In 1868, Johann Friedrich Miescher, a young Swish medical student got excited with an acidic substance that he isolated from pus cells obtained from bandages used to dress human wounds. To obtain large quantities of pus for his experiment, Miescher began purchasing used bandages from surgical clinics in Tuebingen, Germany. He separated pus cells from bandages and treated the cells with pepsin, a proteolytic enzyme that he isolated from stomach of pigs. After pepsin treatment, he recovered an acidic substance that was named as “nuclein” by him. This nuclein was unusual in the sense that it was rich in nitrogen and phosphorous, two elements known at that time to coexist only in certain types of fat. Miescher’s paper on this investigation was published in 1871. At that time, importance of Miescher’s nuclein was not fully appreciated. Even the existence of polynucleotide chains, the key component of the acidic material in Miescher’s nuclein was not documented until 1940s. The role of nucleic acid in storing and transmitting genetic information remained un-established until 1944 and the double-helix structure of DNA was not discovered until 1953 by James Watson and Francis Crick. Even in 1953, many geneticists remained skeptical to accept the role of nucleic acid as the genetic information carrier rather than proteins as nucleic acids exhibited less structural variability than the proteins (Snustad et al., 1997).

So far, we have seen the examples in which mode of inheritance of a particular character is tied to the behaviour of the nucleus or more specifically to the chromosomes. In other words, transmission of a character and its appearance in the individuals can be predicted from the knowledge of chromosome segregation and independent assortment. This analogy gets further strengthened on the ground that the DNA has been considered as the basic genetic material and practically all the cellular DNA is localized in the chromosomes. It has also been seen that DNA does not produce an organism alone but obviously depends upon an already existing medium in order to function. Thus, genotypic effects may considerably get modified by the environment. In the cell itself, one important source of environmental effect is the cytoplasm immediately surrounding the nucleus. The components of the cytoplasm may show wide variation between the individuals and therefore it cannot be ruled out that a genotype in one cytoplasm may function somewhat differently than the same genotype placed directly into another cytoplasm. It is well known fact that the cytoplasmic contribution of one of the parents in form of an egg is considerably larger than the cytoplasmic contribution of the other parent in form of sperm. For example, cross-fertilization between two strains capable of producing both sperm and eggs, leads to contribution of ‘A’ genotype and ‘a’ egg cytoplasm in one case and of ‘B’ genotype and ‘b’ egg cytoplasm in the other case. Thus, the cross-fertilized diploid zygotes have two possible genotypic-cytoplasmic combinations, namely, AB-a, and AB-b depending upon which strain provides the egg. If the egg is contributed by the A parent, then the genotype of the progeny shall be AB-a, and if the egg is contributed by the B parent, then the genotype of the progeny shall be AB-b. If each such cytoplasm produces a unique phenotype, then AB-b would have the same b phenotype as BB-b individuals. Such effects produced by the egg cytoplasm are termed as maternal effects.