*Edited by Carlos Reusser*

Some marine propulsion systems are based on thermal machines that operate under the diesel cycle. Their main advantages, compared to other propulsion systems based on thermal machines, are low specific fuel consumption and greater thermal efficiency. However, their main disadvantages lie in the emissions produced by combustion, such as carbon dioxide (CO2), sulfur oxide (SOx), and nitrogen oxide (NOx). Over the last decade, the International Maritime Organization (IMO) has adopted a series of regulations to reduce these emissions based on the introduction of several energy efficiency designs and operational indicators. In this context, this book focuses on the design and operation efficiency of ships through an analysis of the main propulsion systems. It discusses the use of alternative fuels as well as the integration of hybrid and fully electric propulsion systems.

ISBN 978-1-83969-472-1

Modern Ship Engineering, Design and Operations

Published in London, UK © 2021 IntechOpen © sergeyryzhov / iStock


Preface

Rice is a staple food for about half of the world's population. Since 1960s, rice yield has more than doubled in most parts of the world and has even tripled in certain countries due to considerable progress in the development of high-yield rice varieties and the improvement of crop management practices. In the next three decades to 2050, rice yield must increase by more than 1% annually to meet the growing demand for food that will result from population growth and economic development. This is not an easy task because several new challenges have been brought about by changes in socioeconomic and physical environments related to rice production. In particular, rapid urban expansion has resulted in a labor shortage and an increase in wages for agricultural production; over-use of chemicals (e.g., pesticides) has caused substantial soil degradation and environmental problems; and global climatic change has led to an increase in the appearance of abiotic stress events such as heat, chilling, drought, and flooding. Moreover, as living standards improve, the demand for high-quality rice (e.g., aromatic rice) and healthy food increases. To meet these challenges and changes, greater efforts are required to develop new rice technologies in areas of breeding, production, and processing.

This book describes some recent advances in rice research in terms of crop improvement and breeding (Section 1), crop production and protection (Section 2), and crop quality control and food processing (Section 3). In brief, the first section introduces the progress and prospects of two-line rice breeding in India (Chapter 1), the types and breeding strategies of aromatic rice in India as well as the biochemical, genetic, and molecular aspects and the extraction and quantification methods for aroma in rice (Chapters 2 and 3), the physiological responses to abiotic stresses and the biotechnological and breeding approaches to overcome abiotic stresses in rice (Chapters 4 and 5), and the breeding strategies for developing dual-purpose rice that is bioenergy efficient without compromising grain yield (Chapter 6). The second section introduces rice cultivation in the Northern Eastern Hill Region of India (Chapter 7), the constraints and prospects of rainfed rice production in Kenya (Chapter 8), the status and challenges of rice blast disease and emerging minor diseases of rice in India (Chapters 9 and 10), and the potential role of phylloplane and rhizospheric bacteria in controlling bacterial blight of rice (Chapter 11). The third section introduces the use of near-infrared spectroscopy and machine learning in quality control of rice (Chapter 12), the characteristics of fermented brown rice (Chapter 13), and what we can learn from the history of vitamin A deficiency and how golden rice has the potential to significantly contribute to public health in these 'Covid-times' (Chapter 14).

I am grateful to Dr. Zhaowen Mo at the South China Agricultural University, Dr. Yanhua Zeng at the Jiangxi Agricultural University, Dr. Dahui Huang at the Guangxi Academy of Agricultural Sciences, and Dr. Huabin Zheng, Dr. Yue Wang, Dr. Xumeng Li, Dr. Jiwai He and Dr. Shuying Yang at the Hunan Agricultural University for their help with reviewing chapters.

**Dr. Min Huang**

Rice and Product Ecophysiology, Key Laboratory of Ministry of Education for Crop Physiology and Molecular Biology, Hunan Agricultural University, Changsha, China

Section 1


*2.3.3 Glycosylation*

Glycosylation is a commonly used modification of vacuolar proteins in seeds. The asparagine residue is used for N-linked glycosylation, and vacuolar glycoproteins

#### *Seed Filling DOI: http://dx.doi.org/10.5772/intechopen.106843*

usually have both high mannose content and complex N-linked glycans [46, 48, 49]. This process occurs in the lumen of the endoplasmic reticulum because the polypeptide is still in translation and contains a lipid carrier molecule (dolichol phosphate). There are two main types of oligosaccharide side chains: simple or mannose-rich oligosaccharides, which consist of mannose and N-acetyl-glucosamine, and complex or modified oligosaccharides, which are usually rich in mannose but also contain other residues such as fucose, xylose, and galactose. These oligosaccharide side chains may be found on the same polypeptide [45]. Glycosylation is thought to increase the stability of proteins and assist them in folding and assembly [1].

### *2.3.4 Proteolytic cleavage*

Seed proteins transported by the secretory pathway are often subject to posttranslational proteolytic cleavage, including storage proteins, seed defense proteins, and various vacuolar enzymes (α-mannosidase and thiol proteases). For seed storage proteins, the process begins during the transition to the vacuole and is completed in the vacuole [51]. Polypeptides can be split into two or three smaller peptides, some peptide chains can be removed, and the N- or C-terminus of peptides can be truncated [51, 52]. These modifications, together with glycosylation, could lead to a heterogeneous pool of mature proteins derived from a single polypeptide. Among storage proteins, 2S albumins undergo the largest posttranslational modifications [1, 45].

### *2.3.5 Formation of disulfide bonds*

Many seed proteins must have disulfide bonds to stabilize their tertiary and quaternary structures. Disulfide bond formation occurs through disulfide isomerase, which promotes disulfide formation, isomerization or reduction, in newly formed proteins [53]. The enzyme interacts with unfolded proteins in the endoplasmic reticulum and catalyzes thiol oxidation and disulfide exchange reactions.