271 Chapters
Medium 9781780641836

5 Light-mediated Germination

Gallagher, R.S., Editor CAB International PDF

5

Light-mediated Germination

Thijs L. Pons*

Department of Plant Ecophysiology, Institute of Environmental

Biology, Utrecht University, Utrecht, the Netherlands

Introduction

The light response of seeds can control the time and place of germination of a seed, a crucial factor in the survival of the resulting seedlings, and the growth and fitness in subsequent developmental stages. The ultimate effect of light on seeds depends on genotype, and on environmental factors during ripening of the seeds, during dormancy and during germination itself. These environmental factors may include light, or factors other than light such as soil temperatures and soil chemical factors (see Chapter 6 of this volume). The picture is further complicated by the fact that the light climate itself has various aspects that have different effects on seeds, such as irradiance, spectral composition and duration of exposure of the seeds. All the above-mentioned factors can interact in one way or another in their effect on seeds. Moreover, the factors are not constant in time and are difficult to characterize at the seed’s position in the soil, thus complicating further the analysis of what is actually happening with a seed in a natural situation and the interpretation of a possible ecological significance of light responses.

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Medium 9781780642789

Sesame (Sesamum indicum Linn.)

Kumar, P.; Sharma, M.K. CAB International PDF

SESAME (Sesamum indicum Linn.)

NITROGEN (N) DEFICIENCY

Symptoms

Plate 444. Entire plant appearing chlorotic with more pronounced effect on lower leaves.

(Photo by Dr Prakash Kumar.)

1. Increased nitrogen nutrition results in increased protein level and decreased oil content.

2. Improved nitrogen nutrition increases non-amino acid forms of nitrogen.

3. The nitrogen-deficient plant shows poor growth. The stem becomes short and thin.

4. The plant has poor branching. The number and size of capsules are drastically reduced and fewer seeds are produced per capsule.

Crop yield declines sharply.

5. Paling of the entire plant occurs due to lack of chlorophyll content in the leaves.

6. Nitrogen is fairly mobile within plants, thus it is quickly retranslocated from older to younger tissues when the supply to the plant is restricted.

7. The deficiency symptoms become evident first and more severely on the older leaves, then gradually progress to the upper leaves (Plate 444).

8. The severely deficient bottom leaves die and shed prematurely.

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Medium 9781786391216

11: Central Metabolism and Its Spatial Heterogeneity in Maize Endosperm

Larkins, B.A. CABI PDF

11  Central Metabolism and Its Spatial

Heterogeneity in Maize Endosperm

Hardy Rolletschek1, Ljudmilla Borisjuk1, Tracie A. Hennen-Bierwagen2 and Alan M. Myers2,*

1

Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Department of

Molecular Genetics, Gatersleben, Germany; 2Roy J. Carver Department of

Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, USA

11.1 Introduction

This chapter addresses bioenergetic considerations of the metabolic processes in maize kernels by which sugars are converted to starch, protein, and other metabolites. Central metabolism in this context is divided into modules: (i) hexose and sucrose supply;

(ii) hexose phosphorylation; (iii) ATP production; (iv) starch biosynthesis; (v) amino acid biosynthesis; (vi) storage protein synthesis; and (vii) lipid biosynthesis. The components of each node are a group of enzymes and the genes encoding them, so queries of RNA transcripts and quantitative proteomics reflect these metabolic pathways. Flux analysis is relatively well developed for maize endosperm and provides information about rates of metabolic interconversions in particular nodes. Connected metabolic pathways can be proposed based on these considerations and models tested by perturbing them.

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Medium 9781780642789

Cluster bean (Cyamopsis tetragonoloba (L.) Taub)

Kumar, P.; Sharma, M.K. CAB International PDF

CLUSTER BEAN (Cyamopsis tetragonoloba (L.) Taub)

NITROGEN (N) DEFICIENCY

Symptoms

Plate 308. Entire plant appearing light green. (Photo by Dr Prakash Kumar and Dr Manoj Kumar Sharma.)

1. Nitrogen deficiency is usually found during the initial stages of crop growth when root symbiotic nitrogen fixation nodules are yet to develop.

2. Nitrogen deficiency may also occur during later stages of crop growth when the symbiotic nitrogen-supplying mechanism is disturbed for some reason such as nodule infestation, nodule pathogenic disease or physiological causes.

3. Nitrogen is mobile in plants and under short supply conditions it is easily mobilized from older to younger leaves. The deficiency symptoms appear first and more severely on old leaves (Plate 307).

4. In mild deficiency conditions or when deficiency occurs in the young stage, the entire plant appears uniformly light green in colour (Plates 308 and 309).

5. If deficiency persists and becomes more severe, the older leaves show uniform pale green to pale yellow chlorosis (Plate 307).

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Medium 9781780648200

9: Entomopathogenic Nematodes for Management of Insect Pests of Canola and Other Oilseed Crops

Reddy, G.V.P. CABI PDF

9

Entomopathogenic Nematodes for Management of Insect Pests of Canola and Other Oilseed Crops

Harit K. Bal1* and Parwinder S. Grewal2

1

Michigan State University, East Lansing, Michigan; 2University of Texas Rio

Grande Valley, Edinburg, Texas

9.1  Introduction

Insect pests cause significant problems to agricultural crops all over the world (Pedigo and Rice, 2009).

To control these insect pests, chemical insecticides are being readily used with a worldwide expenditure of US$58.46 billion in 2015 (Mordor

Intelligence, 2016). The excessive and indiscriminate use of chemical insecticides has a detrimental impact on the environment and human health

(Pimental, 2005). In order to overcome such harmful side effects of insecticides, application of biological control agents, including microorganisms, predators and parasitoids, has been encouraged for pest management. Entomopathogenic nematodes

(EPNs), belonging to families Heterorhabditidae and

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