eChapters

16.1 INTRODUCTION

Portulaca is an annual potherb, but may be perennial in the tropics. In many parts of the world, it is still regarded as a weed with nutritional potential. Its young stems and leaves are succulent and edible with a slightly acidic and salty taste. Stems are glabrous, f leshy, purplish-red to green, arising from a taproot, often prostrate, forming mats. It is described as a power food of the future because of its high nutritive and antioxidant properties. It contains more omega-3 fatty acids (300 to 400 mg/100 g of fresh leaves) than any other leafy vegetable plant. Succulent leaves and stem also contain dietary minerals, such as calcium, phosphorus, iron and potassium, as well as vitamins A, C and E and some amount of vitamin B and carotenoids. It has been recommended as a cholesterol lowering agent and as a therapy for arteriosclerosis. Generally, roots and leaves contain more iron and manganese than stems. Due to oxalic acid and nitrate content, excessive consumption of purslane is not recommended. The cultivated form of Purslane, i.e., Portulaca oleracea (garden or green purslane) and Portulaca sativa (yellow leaves, less hardy than the green purslane but possessing the same qualities), is hexaploid. Purslane is a succulent and well-branched herb, leaves are spirally arranged, f lowers are yellow, stamens 7-10, style with arms, fruit ovoid, capsule, seeds numerous, tiny and black in colour.

1. SEED DRYING

The process of elimination of moisture from the seed is called drying.

2. STAGE OF MOISTURE ELIMINATION

The moisture from the seed is eliminated in 2 stages

1. Surface moisture of the seed that initially removed by the drying air.
2. The removal of the moisture in the surface cause an imbalance in the moisture potential in the surface of the seed and the inner portion of the seed which leads to the migration of moisture from the inner organ to the surface.

The migration of moisture to the surface is slower than the evaporation and a moisture gradient is developed in the kernel. Elimination of moisture from the seed depends upon the relative humidity and temperature of the environment surrounding the seed.

A line homozygous at all loci, ordinarily obtained by successive self-fertilizations in plant breeding is called a pure line. This concept was proposed by Danish biologist, W.L. Johannsen in 1903 while conducting a series of selection experiments for seed weight in common bean, which is strictly self-pollinated species. This is applied in self-pollinated crops, like wheat, rice, pulses, several vegetable crops, namely, tomato, chilli, eggplant, okra, cucurbits, etc. This is also applied to develop inbred parental lines in maize and several other cross-pollinated crops. However, ultimately these parental lines are used in development of new hybrids. This could be summarized as follows:

• Lines that are genetically different may be successfully isolated from within a population of mixed genetic types.
• Any variation that occurs within a pure line is not heritable but due to environmental factors only. Consequently, as Johansen’s bean study showed, further selection within the line is not effective.

Plant growth

Definition: The quantitative increase in plant body such as increase in the length of stem and root, the number of leaves etc., is referred to as plant growth.

Plant development

Definition: The qualitative changes such as germination of seed, formation of leaves, flowers and fruits, falling of leaves and fruits is referred as developement.

Phytohormones

Definition: These are the organic substance or hormones produced by plants which in low concentrations regulate plant physiological process. It is synthesized in one part of plant and translocated to other parts. These are endogenous substance means naturally occurring in the plant.

There are several systems for greenhouse heating based on heat source and purpose or crops to be produced in greenhouse.

Electric heaters

Unit space heaters, either floor mounted or supported, are normally dependent on electricity supply supported by stand-by generators. Abroad they are fuelled with natural or bottled gas or fuel oil and use fans for heat distribution. This system requires a relatively moderate capital investment, is easy to install, and provides for easy expansion of facilities. If unit air heaters are used, they should be spaced and directed to blanket the entire area with heated air.

Hot Water Systems

Hot water systems utilize metal pipes that can be perimeter, under benches, or overhead fan forced unit heaters can be used. This system requires a boiler, valves, and other necessary controls. Hot water system is simpler to install and normally requires less maintenance than a steam system. Hot water systems are mainly used in smaller greenhouse.

Biofertilizers

Definition: Biofertilizers are defined as preparations containing living cells or latent cells of efficient strains of micro–organisms that help crop plant’s uptake of nutrient by their interaction in the rhizosphere when applied through seed or soil. They accelerate certain microbial process in the soil which augments the extent of availability of nutrient in a form easily assimilated by plants.

Types of biofertilizers

There are some types of biofertilizers:

1. Nitrogen fixing biofertilizers
2. Phosphorus solubilizing biofertilizers
3. Phosphorus mobilizing biuofertilizers
4. Biofertilizers for micro–nutrients
5. Plant growth promoting rhizobacteria

1. MINIMUM SEED CERTIFICATION STANDARDS

In a seed quality control programme through seed certification, the minimum seed certification standards, in fact, are the minimum standard conditions which must be met. The minimum seed certification standards, thus are the standards required for the certification of seeds by the certification agencies.

The minimum seed certification standards can be broadly grouped into two groups.

Introduction

Musa species and cultivars are identified mainly on the basis of morphological characters. Somatic mutations and changes brought about by environment are major obstacles to the accurate identification of clones (Kaemmer et al., 1992). Isoenzymatic markers provide an additional tool for the characterization of germplasm and have been successfully employed in banana to provide better understanding of somaclonal variants and to detect genetic differences at clonal level.

Being located within the center of diversity of cultivated banana, the South Indian state of Kerala accounts for a large share of variability, especially the AA, AB, AAB and ABB genomic groups.Nendran, the French plantain cultivar indigenous to Kerala (Jacob, 1952) is represented by many ecotypes/clones. Other prominent cultivar groups include Mysore (AAB), Rasthali (AAB), Neypoovan (AB), Kunnan (AB), Monthan (ABB) and Karpooravalli (ABB). The variability has been collected and conserved in the field at the Banana Research Station, Kannara. These have been characterized morphologically employing per INIBAP/IPGRI Musa descriptors, facilitating the identification of distinct cultivars, clones and synonyms.This project was initiated to survey the isozyme polymorphism in the cultivar groups and to select suitable system for clonal identification.Results of the study employing three enzymatic systems -esterase, diaphorase and peroxidase are presented

A variety produced by crossing inter se a number of genotypes selected for good general combining ability in all hybrid combinations with subsequent maintenance of the variety by open-pollination. Synthetics development is common in cross- pollinated crops in the early phases of breeding. The synthetic method of breeding is suitable for improving cross-fertilized crops. It is widely used to breed forage species. Successful synthetic cultivars have been bred for corn, sugar beets, and other species like cauliflower in India. The suitability of forage species for this method of breeding stems from several biological factors. Forages have perfect flowers, making it difficult to produce hybrid seed for commercial use. The use of male sterility may facilitate controlled cross-pollination, which is difficult to achieve in most forage species. To test individual plants for use in producing the commercial seed, it is essential to obtain sufficient seed from these plants. The amount of seed obtained from single plants of these species is often inadequate for a progeny test. Furthermore, forage species often exhibit self-incompatibility, a condition that inhibits the production of selfed seed. Synthetic cultivars are also used as gene pools in breeding progeny. Synthetic cultivars are advantageous in agricultural production systems where farmers routinely save seed for planting. One of the well-known and widely used synthetic has been the Iowa stiff- stalk synthetic (BSSS) of maize.

Composites defined as advanced generation populations maintained by random mating in the material constituted through mixing of equal quantity of seeds of crosses showing less inbreeding depression in F2 over F1. The components of composites inbreds, open-pollinated populations, locally available open-pollinated cultivars, hybrids, advanced generation lines, improved populations. Mixing the seeds of several phenotypically outstanding lines produces a composite variety and encouraging open pollination to produce crosses in all combinations among, the mixed lines. The lines used to produce a composite variety are rarely or not tested for combining ability with each other like as done in case of synthetics where the combining ability of the component lines is invariably tested for GCA. Composite are commercial varieties and are maintained by open - pollination in isolation. While mixing the seeds of various genotypes, care should be taken that the component lines are similar in maturity height, seed size, colour, etc. so that the composite maintained through random mating in isolation manifests a reasonable degree of phenotypic uniformity. The variety is maintained by open pollination. Farmers can use their own seed for 3 to 4 years.

1. SEED PURITY AND ITS COMPONENTS

Seed purity analysis from the working sample taken from submitted sample is made in accordance to ISTA rules. The uncertified seed sample is generally a mixture of pure seeds, inert matter and biological impurities including genetically impure seeds of the variety.

A buyer expects to have good seed and not a mixture of pure seed with a high percentage of chaff, straw, sand, weed seeds and other crop seeds and also genetically impure or mixed seeds.

Purity analysis is a test to estimate the extent of biotic and abiotic impurities present in the seed lot of a variety.

Nutrient film technique popularly known as NFT is one of the methods of soilless farming or hydroponics where in plants have their roots in a shallow stream of recirculating water containing all the nutrients required for plant growth dissolved without any solid growing medium. The lower portion of roots remain submerged in flowing nutrient medium in a water tight gully having enough air for the roots. The nutrient film technique was developed during the late 1960s by Dr Allan Cooper at the Glasshouse Crop Research Institute, England. The method is already used in commercial horticulture in many countries including India. NFT is potential for other crops such as animal fodder and even energy-source plants for fuel production.

NFT related technologies

Hydroponics : Cultivation of plants in nutrient solutions is known as hydroponic cutlivation. This ia gerally done under protected structures and in containers arranged horizontally or vrtically (vertical garden). Use of nutrient film or fertilizers is made to feed the plants. Hydroponics can be practiced following nutrient film technique method, trough method, deep water floating method and coco peat bag culture.

The relative long periods of time required for completion of germination tests delays the seed marketing. This necessiated the development of rapid methods for estimating the germination capacity of seeds. This test was developed by Lakon (1942) in Germany.

1. PRINCIPLE

It is a biochemical test, in which living cells are made visible by reduction of an indicator dye. The indicator used is 2,3,5 triphenyl tetrazolium chloride. Within the seed tissues, it interferes with the reduction processes of living cells and accepts hydrogen from the hydrogenases. By hydrogenation of the 2,3,5-triphenyl tetrazolium chloride, a red stable and non diffusible substance, triphenyl formazan is produced in living cells (Fig. 1).

ABSTRACT

The cry1A genes of Bacillus thuringiensis (Bt) are widely used to engineer lepidopteran insect resistance in crop plants including horticultural crops. Continuous exposure of a single kind of Bt toxin can lead to resistance development in insect pest. Due to the difference in structure and unique insecticidal mechanism, cry2A genes are promising candidates for management of resistance development. Since India is rich in biodiversity and genetic resources, indigenous Bt strains are valuable tool for identification of novel cry genes. The present study describes the cloning of cry2Ab from a new indigenous strain of Bt, 14RI. The presence of cry2Ab gene in Bt strain 14RI was confirmed by PCR with primers specific to its internal region. Primers corresponding to the flaking region of cry2Ab were used for amplification of cry2Ab orf from the Bt strain 14RI. The amplified cry2Ab orf was first cloned into the T/A cloning vector, and then fused to the downstream of the cry2Aa promoter along with its orf1 and orf2 in the Bt shuttle vector pHT1301. Acrystalliferous Bt strain 4Q7 has been transformed with recombinant pHT1301 to express the cry2Ab of Bt strain 14RI.

1. FIELD OF APPLICABILITY

Grow-out test is the official measure for controlling the genetic purity of the seed lot. It serves as ‘pre-control’ as well as a ‘post control’ test for avoiding genetic contaminations. According to the official regulations in India, it is prerequisite for seed certification of hybrids of certain species such as cotton, castor, musk melon and brinjal.

The test is conducted for checking the sellers label with respect to genetic purity status of the seed lot under the provisions of the Seeds Act 1966. In addition, grow-out test can also be used as a measure to judge the efficacy of the certification agency or the inspector.

ABSTRACT

Role of cytokinins in the regulation of sink development in potato was studied by transgenic approach. Transgenic potato plants over-expressing Agrobacterium native ipt (gene for isopentenyl transferase, rate limiting enzyme in cytokinin biosynthesis) under the transcriptiona l regulation of tuber specific patatin promoter were developed. Transformants obtained showed normal phenotype, while the cytokinin levels showed significant increase over the control plants for the various cytokinins tested, viz., trans zeatin riboside (tZR), dihydrozeatin riboside (DHZR) and isopentenyl adenosine (iPA). The primary transformants were hardened and tested under green house conditions. Green house studies showed a significant increase in the number of tubers in ipt transformants when compared to the wild plant as well as GUS transformant. However, the total weight of tubers did not show appreciable difference between transformants and control plants. Reduction in the weight of individual tubers appears to be due to source limitation.

ABSTRACT

Chilli (Capsicum annuum L.) is a vegetable and spice crop of worldwide importance. Despite the fact that other closely related members of the Solanaceae family are easily transformed by genetic engineering, capsicum still remains recalcitrant to in vitro manipulation, due to lack of proper elongation of multiple shoot initials. An attempt has been made to standardize transformation protocol in two local cultivars of capsicum viz., Byadgi dabbi and Sankeshwar, using shoot tip explants.

The Shoot tip explants were co-cultivated (for 2 days) with Agrobacerium strain EHA105 harboring pBinBt3 plasmid having cry1AC gene and nptII marker linked to the CaMV 35S promoter and nos terminator. After co-cultivation shoot tips were transferred to MS medium containing 2mg/l IBA, 100mg/l kanamycin and 300mg/l cefotaxime. Survived plants were checked for the presence of transgene using cry1 AC and npt II specific primers. Expression of cry1AC gene in these plants was checked using DesiGen Xpresstrips.

ABSTRACT

Chilli is the universal spice of Kerala, known for its pungency, flavour and colour of fruits. Of the five domesticated species of Capsicum, C. annuum is the most extensively cultivated one. Bell pepper (C. annuum L.) is mainly used as a vegetable, because of its low pungency and good flavour. It is used as raw in salads, and also in cooked form. Application of biotechnological tools in this crop for improving the quality, shelf life and tolerance of the crop to stress conditions has been limited. This is mainly due to lack of an efficient regeneration system. We reported a viable protocol for the regeneration of whole plant from the hypocotyl earlier. We also succeeded in developing a protocol for genetic transformation of bell pepper using Agrobacterium tumefaciens. The strain EHA 105 containing gus intron and npt II was used for co-cultivation. The dilution of bacterial culture and time of infection were standardised. This was followed by killing the bacterial cells using cefotaxim @ 250ppm. Transformants were selected on MS medium supplemented with kanamycin. Staining of the regenerants with X-gluc revealed presence of blue spots, confirming transformation. This protocol could be exploited for improving the commercial traits of bell pepper by incorporating desirable genes through Agrobacterium mediated transformation.

ABSTRACT

Holostemma ada-kodien K. Schum, is a laticiferous climber belonging to the family Asclepiadaceae. The root tubers of the plant are medicinally important and are utilized as a major ingredient of the drug, Jivanti. The roots of Holostemma are sweet, ophthalmic, emmolient, alterant, tonic stimulant, aphrodisiac, expectorant and galactagogue and are useful in ophthalmopathy, orchitis, cough, burning sensation, stomachalgia, fever and to cure ‘tridosha’ (Warrier et al., 1995). The sugars and amino acids present in the tuberous roots are responsible for the medicinal properties (Ramiah et al., 1981). There is a huge demand for the root tubers of Holostemma in the South Indian pharmacies and more than 150 metric tons of roots are needed every year (Nair et al., 1992). The destructive and ruthless collection of tuberous roots in recent times has led to acute scarcity of the plant and consequently it has been listed as vulnerable and rare in the FRLHT red list of medicinal plants (FRLHT, 1997). Extending the commercial cultivation of Holostemma is practically impossible due to the increasing land pressure and the perennial nature of the crop. An alternative to meet the increasing demand is to produce the active chemicals in Holostemma through in vitro techniques. In vitro techniques have been extensively studied to produce the different secondary metabolites from various medicinal plants. A strong correlation between secondary metabolite production and morphological differentiation gives more impetus to the application of organized cell culture particularly the root cultures for the large-scale production of phytochemicals in vitro. Transformed root cultures - the so called hairy root cultures obtained after the insertion of T-DNA from the root inducing (Ri) plasmid of the Agrobacterium rhizogenes into the plant genome (Ackermann, 1977) has emerged as an important tool for the production of secondary metabolites in vitro (Rhodes et al., 1987). Hairy roots have advantages of fast growth, organ differentiation and stable secondary metabolite production (Banerjee et al., 1995). We report here the hairy root induction from shoot buds and seedling hypocotyls in infection with A. rhizogenes useful in exploring the possibilities of large-scale in vitro secondary metabolite production in this rare medicinal plant.

1. NEMATODES

Nematodes, also called eel-worms, are wormlike in appearance, but quite distinct taxonomically from true worms. They live freely in fresh or salt water or in soil. They are saprozoic and also parasitize animals (including man) and plants. Many species of nemotdes parasitize higher plants and cause disease symptoms. Plant parasitic nematodes are small (invisible to the naked eye), long, tubular, round in the cross section, unsegmented and smooth invertebrates. They inhibit different parts of plants, namely, roots, stem, flower buds and seeds. Depending on the host-parasite relationship, plant parasitic nematodes may be sedentary or migratory and ectoparasitic and/or endoparasitic in their feeding habits.

1.1. Nematodes

Seed-borne nematodes may be internal or may occur as seed infestation. Several saprozoic soil nematodes occur in beds of soil mixed with seed. Seed infestation by nematodes does not produce any specific symptoms on seed, but in those that occur as endoparasites, the floral structure may be modified into a seed gall (Anguina spp.) may produce symptoms such as discoloration of testa in groundnut (Ditylenchus destructor) or may be symptomless as in paddy kernels infected by Aphelenchoides besseyi. Neergaard (1979) listed five genera - Anguina, Aphelenchoides, Ditylenchus, Heterodora and Rhadinaphelenchus - that are seed-transmitted. Heterodora and Rhadinaphelenchus occur as endoparasites in roots, stems, and leaves. The latter also affects the growing apex, inflorescence and husks of dropped nuts.