Preface

A biological system is an endogenic and dynamic system that always seeks a constant in-flow of energy to maintain its meta-stable condition called homeostasis. Any environmental disruption of this homeostasis may be explicated as biological stress. Biological stress limits the growth and yield potential of a crop and is broadly grouped into biotic and abiotic stresses. Biotic stress is due to interactions between organisms starting from predation to allelopathy. Abiotic stress appears due to the adverse effects of non-living environmental factors (i.e., water, temperature, light, metal, mineral nutrients, etc.) on plants, which are often sporadic and highly localized. Understanding abiotic stress responses in plants are critical for the development of new varieties of crops that are better adapted to harsh climate conditions. This book provides a comprehensive overview of the agronomical, physiological, and molecular basis of plant responses to external stress like salinity, drought, temperature, and heavy metals to aid in the engineering of stress-resistant crops.

Over twenty-two chapters, *Abiotic Stress in Plants* presents a comprehensive picture of plant responses to external stress. It is designed for researchers, technologists, policy makers, and undergraduate and postgraduate students studying sustainable crop production and crop protection. This book is a worthy addition to university libraries and research establishments where agricultural and agronomical sciences are studied and taught. We are thankful to all the authors who contributed their valuable chapters to this book. We are also extremely grateful to IntechOpen's Publishing Process Manager Ms. Sara Gojevic-Zrnic for helping us to publish this book in an excellent form in the shortest possible time. We owe our sincere thanks and irreparable gratitude to our families whose consistent encouragement and love have been a tremendous impetus for completing this book.

> **Dr. Shah Fahad** Agriculture Department, University of Haripur, Haripur Kyhber Paktunkhwa, Pakistan

#### **Dr. Shah Saud and Dr. Yajun Chen**

Horticulture Department, Northeast Agricultural University, Harbin, China

**Dr. Depeng Wang**

College of Life Science, Linyi University, Linyi, China

**Dr. Chao Wu** Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and the Chinese Academy of Sciences, Guilin, China

**1**

**Chapter 1**

**Abstract**

**1. Introduction**

Drought Stress

Kentucky bluegrass drought resistance research.

**Keywords:** Kentucky bluegrass, drought stress, tolerance, mechanism

Drought is one of the major environmental factors that affect plant growth and survival worldwide. Turfgrass as an important part of the green ecosystem in the urban area which provides many kinds of environmental functions such as beautify and green the city, cooling warm weather, and soil stabilization. As urban rapid expansion nowadays, the percentage of land converted into turfgrass has been increasing. Turfgrasses are generally classified into cool- and warm- season groups based on their adaptation to specific ranges in temperature and precipitation, which are mainly governed by latitude and altitude [1, 2]. Kentucky bluegrass (*Poa pratensis* L.) is an excellent cool-season turfgrass and is extensively used in public parks, golf courses and residential lawns in temperate and cold temperate zones and cool plateau areas. This is a highly variable, rhizomatous species. Many improved cultivars of this species have been developed and used in landscaping areas in the world. A wide range of diverse cultivars and accessions of Kentucky bluegrass have been characterized based on pedigree, common turf performance, and morphological characteristics and were grouped into different genotypes such as Common, Compact, Compact-America, Julia, Mid-Atlantic and Midnight types [3]. Although these germplasm possess prominent ornamental value, however, Kentucky bluegrass extremely limiting used by water scarcity in practice, especially in semiarid, arid regions as well as the areas with the increase demand on water for

A Review on Kentucky Bluegrass

Kentucky bluegrass (*Poa pratensis* L.) is an excellent cool-season turfgrass and is extensively used in urban green space, parks and sports fields worldwide, but it is sensitive to drought stress. Drought reduces turf quality of Kentucky bluegrass by influences on the shoot density, texture, uniformity, color, growth habit and recuperative capacity. It has been a challenge for breeding water saving cultivars and enhances water use efficiency in Kentucky bluegrass. Many studies have revealed the mechanisms of drought stress tolerance in Kentucky bluegrass via multiple approaches. The morphological and physiological attributes as well as molecular information were discovered for better understanding and improving its drought tolerance. In this chapter, we will draw a systematic literature review about Kentucky bluegrass in response to drought stress and provide future perspectives of

Responses and Tolerance to

*Jian Cui, Saud Shah, Shah Fahad and Yajun Chen*

#### **Chapter 1**
