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History of insecticidal control of rice planthoppers in Asia and associated resistance development is summarized. Rice planthoppers have developed resistance against all the insecticides that were commonly used. Experiences of past 30 years of chemical control of the rice planthoppers in many parts of Asia confirm that the use of any kind of insecticide for long time leads to the development of resistance. Overseas migration of rice planthoppers may markedly affect the status of insecticide resistance in populations over long distances, and the effects of migration can be maintained at least until the following year. It is possible that insecticide resistance may spread as a result of intercrossing between resistant immigrant and susceptible domestic populations. When insecticides are used against major pest, such planthoppers also produce selection pressure on the potential pests. It is believed that the resistance of small brown planthopper (SBPH) to insecticides is one of the important factors behind the recent outbreaks of smaller BPH in China. Pesticide-induced resurgence involves ecological and physiological factors. Many of the pesticides stimulate the reproduction of the brown planthopper (BPH), and sublethal dosages increase its reproduction. Decimation of natural enemy by pesticides is an important ecological factor for the induction of BPH resurgence, but stimulation of reproduction by pesticides is more responsible for the occurrence of resurgence. Insecticide resistance and pest resurgence caused by insecticides and their outcome result in occurrence of outbreak or resurgence of pests. Pesticides also affect physiology and biochemistry of rice plant in different ways. Insecticide resistance and insecticide-induced resurgence are closely related, and resultant outcome is pest outbreak or resurgence.

The bulk of this book is devoted to the arsenic biogeochemical cycles in the paddy rice systems, the mechanisms of arsenic uptake and accumulation by rice plants, dietary arsenic intake from rice and potential mitigation methods to reduce arsenic accumulation in rice. The reasons for the focus on rice are explained in Chap. 1. Nevertheless, it is necessary to consider other food crops with regard to their arsenic contents, speciation and likely contributions to the dietary intake of As, which is the task of this chapter.

It is now 20 years since a suggestion was first made of introducing a C4 photosynthetic pathway into rice plants to increase rice productivity. With the amount of arable land decreasing, the human population increasing and rice productivity plateauing there is an urgent need to significantly increase rice productivity. One way of increasing rice productivity is by introducing the C4 photosynthetic pathway into rice by genetic manipulation. Over the past decade, a number of attempts have been made to modify the photosynthetic pathways present in C3 plants by introducing genes encoding enzymes associated with C4 photosynthesis. These efforts have increased the expression of specific enzymes such as pyruvate, orthophosphate dikinase, phosphoenolpyruvate carboxylase and NADP-malic enzyme in a range of plants, notably rice, tobacco, and potato. Claims and counter claims have been made regarding the success of attempts to construct a C4 rice plant, but to date, no functional C4 pathway has been engineered into C3 species. Novel approaches are now required to introduce a functional C4 photosynthetic pathway into rice and this may require a change to the molecular architecture of photosynthetic tissue (introduction of Kranz anatomy), the coordinated co-expression of enzyme regulatory mechanisms and the expression of specific transporters in rice leaves.

Rice is unique among the world’s major food crops by virtue of the extent and variety of its uses and adaptability to a broad range of climatic, edaphic, and cultural conditions (Mikkelsen and Datta, 1991). It provides 20% of the per capita energy and 15% of the per capita protein for humans worldwide. Annual world rice production is approximately 460 million tons grown on more than 145 million ha. Over 90% of this area lies in Asia, while the remainder is divided among Latin America, Africa, Australia, Europe, and the USA (see Way and Bowling, 1991).

Introduction Rhizobium is the most thoroughly studied diazotroph due to its ability to induce nitrogen -fixing root nodules on leguminous plants and provide them with nitrogen nutrient (1). Recently many research studies have shown that rhizobia can also colonize the root interior of nonlegumes (2-6). R. leguminosarum bv. trifolii can endophytically colonize rice roots, promoting the plant’s growth and grain yield under lab and field conditions (2, 5). In spite of the widespread occurrence of natural endophytic rhizobia-cereal associations, much remains unknown about its infection and colonization processes. Here we examined the infection process throughout the growth cycle of the rice plant.

Most plants have the ability to fight off pathogens by invoking various defense systems, including systemic acquired resistance (SAR). Chemicals that activate SAR are called plant activators. Among the most effective known plant activators is probenazole (3-allyloxy-1,2-benzisothiazole-1,1- oxide; PBZ, Figure 1), developed by Meiji Seika Kaisha Ltd. Oryzemate® granule, containing PBZ, has been widely used against rice blast by Japanese farmers since 1975. In the past several years, it has been applied in some 25–30% of all paddy fields in Japan to control blast. Since PBZ activates plant defense systems, the study of PBZ’s mode of action has helped clarify how rice plant defense systems function. These studies suggest that PBZ is not only an essential protectant for rice cultivation, but also a useful probe in research into plant defense mechanisms.