**Breeding for Drought Resistance Using Whole Plant Architecture — Conventional and Molecular Approach**

H.E. Shashidhar, Adnan Kanbar, Mahmoud Toorchi, G.M. Raveendra, Pavan Kundur, H.S. Vimarsha, Rakhi Soman, Naveen G. Kumar, Berhanu Dagnaw Bekele and P. Bhavani

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/54983

**1. Introduction**

Drought, also referred to as low-moisture stress, is a form of abiotic stress. It is a challenge posed by the environment to the survival and productivity of a plant/crop that occupies a large area. This directly translates to economic loss to the farmer(s) who depend on the harvest. The plant has a wide range of genetic and phenological adaptations innate or triggered to cope with the stress. The extent of loss to productivity depends on the periodicity (over years), timing within the season when it occurs, rate of onset of the stress, severity, duration and a few other minor factors. At certain geographical locations, drought occurs at periodical intervals over years in a cycle. Should it occur, all the stages of the crop are likely to be affected. Vulnerability of crops to drought is likely to be intensified due to climate change [1].

When challenged by drought, a plant struggles to survive. If it succeeds to survive, it tries to complete the life cycle, which in annual crops means production of grains. When challenged by stress the phenology of the plant is severely altered. Altered phenology is often reflected as advancing flowering and maturity or by delaying flowering so that the critical stages of the crop do not get severely affected. Either way, it tries to circumvent the stressful period. This is a form of drought escape. The pattern of response will depend on the time of onset, intensity and nature of stress. Alternatively, it triggers a series of biological processes that helps the plant take the challenge 'head on' and complete the lifecycle with high grain yields. It is this pattern of responses that are a subject matter of systematic plant breeding endeavor. Collec‐ tively the latter strategy is referred to as drought resistance and scientists seek to study, understand and use it to enable farmers to get as good a harvest as possible.

© 2013 Shashidhar et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Shashidhar et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Daek blue – countries with plentiful water (>1,700 m3/person/day) Medium blue – countries with water stress (<1,700 m3/person/day) Light blue countries with water scarcity (<1,000 m3/person/day)

**Figure 1.** Water scarcity map of the most vulnerable parts of the world. Left 2005, Right 2015. Borrowed from "Blue revolution initiative Strategic framework for Asia and the Near East, Bureau for Asia and the Near East, USAID, May 2006. P 37 [2]"

Breeding for drought tolerance in any given crop, has immense value to the farmers as their livelihood depends on the harvest(s). It bears a positive effect on the farmers' economic health, family well-being and harmony in the society. It affects poor farmers more than the rich ones. Complete or partial loss of harvest in drought years is known to trigger panic reaction, migration and decrease or extinction of flora and fauna of the particular habitat. There have been scores of farmer suicides due to losses caused by drought and associated problems in different States of India [3, 4]. A link between drought and suicides has been established in Australia [5], Africa, and in the South America. Thus as a trait, drought resistance has immense value to the individual farmer and the society. According to [6] the "future imperative is clear —Asia cannot continue to depend on the quantity and quality of freshwater for rice cultivation in the traditional manner".
