Incidence and intensity of drought and low N stresss in the tropics; Case studies strategies for crop production under drought and low n stresses in the tropics; Stress physology and identification of secondary traits; Physiology of low nitrogen stress; Breeding for tolerance to drought and low n stresses; General breeding strategies for stress tolerance; Progress in breeding drought tolerance; Progress in breeding low nitrogen tolerance; Experimental design and software.

Nitrogen is an essential element for plant growth and development and a key agricultural input-but in excess it can lead to a host of problems for human and ecological health. Across the globe, distribution of fertilizer nitrogen is very uneven, with some areas subject to nitrogen pollution and others suffering from reduced soil fertility, diminished crop production, and other consequences of inadequate supply. Agriculture and the Nitrogen Cycle provides a global assessment of the role of nitrogen fertilizer in the nitrogen cycle. The focus of the book is regional, emphasizing the need to maintain food and fiber production while minimizing environmental impacts where fertilizer is abundant, and the need to enhance fertilizer utilization in systems where nitrogen is limited. The book is derived from a workshop held by the Scientific Committee on Problems of the Environment (SCOPE) in Kampala, Uganda, that brought together the world's leading scientists to examine and discuss the nitrogen cycle and related problems. It contains an overview chapter that summarizes the group's findings, four chapters on cross-cutting issues, and thirteen background chapters. The book offers a unique synthesis and provides an up-to-date, broad perspective on the issues of nitrogen fertilizer in food production and the interaction of nitrogen and the environment.

Maize is one of the world’s highest value crops, with a multibillion dollar annual contribution to agriculture. The great adaptability and high yields available for maize as a food, feed and forage crop have led to its current production on over 140 million hectares worldwide, with acreage continuing to grow at the expense of other crops. In terms of tons of cereal grain produced worldwide, maize has been number one for many years. Moreover, maize is expanding its contribution to non-food uses, including as a major source of ethanol as a fuel additive or fuel alternative in the US. In addition, maize has been at the center of the transgenic plant controversy, serving as the first food crop with released transgenic varieties. By 2008, maize will have its genome sequence released, providing the sequence of the first average-size plant genome (the four plant genomes that are now sequenced come from unusually tiny genomes) and of the most complex genome sequenced from any organism. Among plant science researchers, maize has the second largest and most productive research community, trailing only the Arabidopsis community in scale and significance. At the applied research and commercial improvement levels, maize has no peers in agriculture, and consists of thousands of contributors worthwhile. A comprehensive book on the biology of maize has not been published. The "Handbook of Maize: the Genetics and Genomics" center on the past, present and future of maize as a model for plant science research and crop improvement. The books include brief, focused chapters from the foremost maize experts and feature a succinct collection of informative images representing the maize germplasm collection.

A field experiment was conducted at farmer’s field of Anandapur, Mangalpur VDC-3, Chitwan, Nepal during winter season from September 2006 to February 2007 to study the effects of nitrogen and plant population on maize. Fifteen treatment combinations consisting of five levels of nitrogen: 0, 50, 100, 150 and 200 kg N/ha and three levels of plant population; 55555 plants/ha (60 cm × 30 cm spacing), 66666 plants/ha (60 cm × 25 cm spacing) and 83333 plants/ha (60 cm × 20 cm spacing) were tested in factorial randomized complete block design (RCBD) with 3 replications. “Rampur Composite” variety of maize was planted on sandy silt loam and strongly acidic soil having medium in total nitrogen (0.123%), high in soil available phosphorous (77.56 kg/ha) and low in soil available potassium (23.25 kg/ha). The research findings revealed that each level of nitrogen significantly increased grain yield upto 200 kg N/ha. The grain yield (6514.48 kg/ha) obtained under 200 kg N/ha was significantly higher than that of 0, 50, 100 and 150 kg N/ha. The percent increment in yield due to application of 50, 100, 150 and 200 kg N/ha was to the extent of 62.11, 104.74, 135.68 and 154.74%, respectively over control. Significant effect on grain yield due to different levels of plant population was observed. The grain yield (5113.46 kg/ha) obtained under 66666 plants/ha was statistically at par with that under 83333 plants/ha, but significantly superior over that under 55555 plants/ha. The interaction between different nitrogen levels and plant densities on grain yield showed that the highest grain yield (6925.79 kg/ha) was obtained under treatment of 200 kg N/ha + 66666 plants/ha. The yield attributes namely number of cobs/plant, cob length, cob diameter, number of grain rows/cob and 1000 seed weight significantly increased with increasing N levels and decreasing plant population levels. The number of barren plants/ha decreased with increasing levels of N but increased with increasing levels of plant population. The net return (Rs. 42188.74/ha) and benefit:cost ratio (1.67) obtained under 200 kg N/ha were significantly highest than that obtained under other levels of nitrogen (150, 100, 50 and 0 kg N/ha). The plant population of 66666 plants/ha gave the highest net returns (Rs. 25812.28) which was 10.19 and 49.64% higher than that of 83333 plants/ha and 55555 plants/ha, respectively. The benefit: cost ratio (1.44) obtained under 66666 plants/ha was significantly higher than that of 55555 and 83333 plants/ha. The interaction between different nitrogen levels and plant densities on economics of maize production showed that significantly highest net return (Rs.48606.98) and B:C ratio (1.78) were under treatment of 200 kg N/ha + 66666 plants/ha. The highest grain yield and maximum profit were obtained when maize variety “Rampur Composite” was planted with 200 kg N/ha and plant population level of 66666 plants/ha (60 cm × 25 cm spacing).

Plant Breeding Reviews, Volume 24, Part 2 presents state-of-the-art reviews on plant genetics and the breeding of all types of crops by both traditional means and molecular methods. The emphasis of the series is on methodology, a practical understanding of crop genetics, and applications to major crops.

This single volume explores the theoretical and the practical aspects of crop physiological processes around the world The marked decrease over the past century in the land available for crop production has brought about mounting pressure to increase crop yields, especially in developing nations. Physiology of Crop Production provides cutting-edge research and data for complete coverage of the physiology of crop production, all in one source, right at your fingertips. This valuable reference gives the extensive in-depth information soil and crop professionals need to maximize crop productivity anywhere the world. Leading soil and plant scientists and researchers clearly explain theory, practical applications, and the latest advances in the field. Crop physiology is a vital science needed to understand crop growth and development to facilitate increases of plant yield. Physiology of Crop Production presents a wide range of information and references from varying regions of the world to make the book as complete and broadly focused as possible. Discussion in each chapter is supported by experimental data to make this book a superb resource that will be used again and again. Chapter topics include plant and root architecture, growth and yield components, photosynthesis, source-sink relationship, water use efficiency, crop yield relative to water stress, and active and passive ion transport. Several figures and tables accompany the extensive referencing to provide a detailed, in-depth look at every facet of crop production. Physiology of Crop Production explores management strategies for: ideal plant architecture maximizing root systems ideal yield components maximizing photosynthesis maximizing source-sink relationship sequestration of carbon dioxide reducing the effects of drought improving N, P, K, Ca, Mg, and S nutrition improving micronutrient uptake Physiology of Crop Production is an essential desktop resource for plant physiologists, soil and crop scientists, breeders, agronomists, agronomy administrators in agro-industry, educators, and upper-level undergraduate and graduate students.

Nitrogen (N) is a mineral nutrient that is essential for the normal growth and development of plants that is required in the highest quantity. It is an element of nucleic acids, proteins, and photosynthetic metabolites, therefore crucial for crop growth and metabolic processes. Recently, it was estimated that N fertilizers could meet the 48% demand of the world’s population. However, overuse and misuse of N fertilizers raised environmental concerns associated with N losses by nitrous oxide (N2O) emissions, ammonia (NH3) volatilization, and nitrate (NO3−) leaching. For instance, NH3 is a pollutant in the atmosphere, N2O is a greenhouse gas that has a warming potential 298 times higher than CO2 and contributes to ozone depletion, and NO3− causes eutrophication of water bodies. Agricultural practices account for about 90% of NH3 and 70% of N2O anthropogenic emissions worldwide. The efficient use of N chemical fertilizers can be attained through cultural and agronomic practices. Nitrogen use efficiency (NUE) is an important trait that has been studied for decades in different crops. The grain production or economic return from the per unit supply of N fertilizer simply explained the NUE. Several definitions were suggested by different researchers. NUE can be defined as the product of N uptake efficiency (NUpE) and N utilization efficiency (NUtE). An increase in NUE increases the yield, biomass, quality, and quantity of crops. N is generally applied as chemical fertilizer to the soil, whereas a small amount is added to some crops like grain legumes through the fixation process. On the other hand, crop plants take N through the root system in the form of nitrate or ammonium which is thereby used in different metabolic processes. A number of studies have been conducted to increase the NUE in different crops and it has been indicated that NUE can be improved by agronomic, physiological, biochemical, breeding as well as molecular approaches. Nitrogen is the main limiting nutrient after carbon, hydrogen, and oxygen for the photosynthetic process, phyto-hormonal and proteomic changes, and the growth-development of plants to complete their lifecycle. Excessive and inefficient use of N fertilizer results in enhanced crop production costs and atmospheric pollution. Atmospheric nitrogen (71%) in the molecular form is not available for the plants. For the world's sustainable food production and atmospheric benefits, there is an urgent need to upgrade nitrogen use efficiency in the agricultural farming system. Nitrogen losses are too high, due to excess amount, low plant population, poor application methods, etc., which can go up to 70% of total available nitrogen. These losses can be minimized up to 15–30% by adopting improved agronomic approaches such as optimal dosage of nitrogen, application of N by using canopy sensors, maintaining plant population, drip fertigation, and legume-based intercropping. Therefore, the major concern of modern days is to save economic resources without sacrificing farm yield as well as the safety of the global environment, i.e. greenhouse gas emissions, ammonium volatilization, and nitrate leaching.