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Vadez V.,Indian International Crops Research Institute for the Semi Arid Tropics
Field Crops Research | Year: 2014

Roots have long been proposed as a major avenue of research to improve crop adaptation to water limitations. The simple assumption is that deeper and more profuse root systems could tap extra water from the soil profile and alleviate drought effects. However, after decades of research, success in breeding cultivars with improved root systems is lagging behind. Here, we attempt to analyze the possible reasons for this, and re-focus on what root traits might provide the most promising avenues for drought adaptation. We approach the root system from the angle of water extraction, using data from a lysimetric system that allows monitoring and comparing plant water use over the entire crop life cycle and yield, and analyze whether and how differences in water extraction lead to improved yield across different crops. The main message from that analysis is that water extraction during reproduction and grain filling is critical and comes from a number of traits that influence the rate at which plant use the available water before and during stress. Roots may have an effect on this, not from the traditionally thought density or depth, but rather from their hydraulic characteristics. Plants can indeed control water use by controlling leaf area development and this is a "long term" control. Plants also control water losses by controlling stomata opening under high vapor pressure deficit (VPD) conditions, in a transient manner. Both processes (leaf development and stomata opening) are mostly controlled by hydraulic processes. The role of roots in drought adaptation could be there, along with the soil, in setting an hydraulic environment that allow plants to use water in a way that allow maximizing water use for these critical stages. © 2014 The Authors. Source

War A.R.,Indian International Crops Research Institute for the Semi Arid Tropics
Plant signaling & behavior | Year: 2012

Plants respond to herbivory through various morphological, biochemicals, and molecular mechanisms to counter/offset the effects of herbivore attack. The biochemical mechanisms of defense against the herbivores are wide-ranging, highly dynamic, and are mediated both by direct and indirect defenses. The defensive compounds are either produced constitutively or in response to plant damage, and affect feeding, growth, and survival of herbivores. In addition, plants also release volatile organic compounds that attract the natural enemies of the herbivores. These strategies either act independently or in conjunction with each other. However, our understanding of these defensive mechanisms is still limited. Induced resistance could be exploited as an important tool for the pest management to minimize the amounts of insecticides used for pest control. Host plant resistance to insects, particularly, induced resistance, can also be manipulated with the use of chemical elicitors of secondary metabolites, which confer resistance to insects. By understanding the mechanisms of induced resistance, we can predict the herbivores that are likely to be affected by induced responses. The elicitors of induced responses can be sprayed on crop plants to build up the natural defense system against damage caused by herbivores. The induced responses can also be engineered genetically, so that the defensive compounds are constitutively produced in plants against are challenged by the herbivory. Induced resistance can be exploited for developing crop cultivars, which readily produce the inducible response upon mild infestation, and can act as one of components of integrated pest management for sustainable crop production. Source

Sahrawat K.L.,Indian International Crops Research Institute for the Semi Arid Tropics
Archives of Agronomy and Soil Science | Year: 2012

The lowland rice system in Asia makes a major contribution to the global rice supply and is often cited as an example of a sustainable system in which two or three crops of rice are grown in sequence under submerged conditions. However, water shortages are becoming critical in some regions for lowland rice cultivation; and there is high potential in exploring rice cultivation under moisture regimes that save water and also increase productivity. The objective of this article therefore is to analyze the consequences of switching growing of rice from flooded to aerobic conditions on soil fertility and its management. Fertility advantages of submerged rice include amelioration of chemical fertility, preferential accumulation of organic matter and improved availability of major, secondary and selected micronutrients, which contribute to the long-term maintenance of soil fertility and sustainability of the lowland rice system. However, the fertility problems under aerobic rice are better addressed with the crop as a component of a cropping system because continuous growing of aerobic rice in sequence does not seem sustainable due to complex, site-specific chemical and biological constraints. © 2012 Copyright Taylor and Francis Group, LLC. Source

Varshney R.K.,Indian International Crops Research Institute for the Semi Arid Tropics | Varshney R.K.,University of Western Australia | Terauchi R.,Iwate Biotechnology Research Center | McCouch S.R.,Cornell University
PLoS Biology | Year: 2014

Next generation sequencing (NGS) technologies are being used to generate whole genome sequences for a wide range of crop species. When combined with precise phenotyping methods, these technologies provide a powerful and rapid tool for identifying the genetic basis of agriculturally important traits and for predicting the breeding value of individuals in a plant breeding population. Here we summarize current trends and future prospects for utilizing NGS-based technologies to develop crops with improved trait performance and increase the efficiency of modern plant breeding. It is our hope that the application of NGS technologies to plant breeding will help us to meet the challenge of feeding a growing world population. © 2014 Varshney et al. Source

Sharma H.C.,Indian International Crops Research Institute for the Semi Arid Tropics
Journal of Crop Improvement | Year: 2014

Global warming and climate change will trigger major changes in diversity and abundance of arthropods, geographical distribution of insect pests, insect population dynamics, insect biotypes, herbivore-plant interactions, activity and abundance of natural enemies, species extinction, and efficacy of crop protection technologies. Changes in geographical range and insect abundance will increase the extent of crop losses and, thus, will have a major bearing on crop production and food security. Distribution of insect pests will also be influenced by the changes in cropping patterns triggered by climate change. Major insect pests, such as cereal stem borers (Chilo, Sesamia, and Scirpophaga), pod borers (Helicoverpa, Maruca, and Spodoptera), aphids, and whiteflies may move to temperate regions, leading to greater damage in cereals, grain legumes, vegetables, and fruit crops. Host-plant resistance, biopesticides, natural enemies, and synthetic chemicals are some of the potential options for integrated pest management. However, the relative efficacy of many of these pest control measures is likely to change as a result of global warming. Climate change will also result in increased problems with insect-transmitted diseases. These changes will have major implications for crop protection and food security, particularly in developing countries where the need to increase and sustain food production is most urgent. Long-term monitoring of population levels and insect behavior, particularly in identifiably sensitive regions, may provide some of the first indications of a biological response to climate change. Copyright © Taylor & Francis Group, LLC. Source

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