Handbook of LEGUMES of World Economic Importance

Pulse proteins: Processing, characterization, functional properties and applications in food and feed

Inputs of biologically fixed N into agricultural systems may be derived from symbiotic relationships involving legumes and Rhizobium spp., partnerships between plants and Frankia spp. or cyanobacteria, or from non-symbiotic associations between free-living diazotrophs and plant roots. It is assumed that these N2-fixing systems will satisfy a large portion of their own N requirements from atmospheric N2, and that additional fixed N will be contributed to soil reserves for the benefit of other crops or forage species. This paper reviews the actual levels of N2 fixation attained by legume and non-legume associations and assesses their role as a source of N in tropical and sub-tropical agriculture. We discuss factors influencing N2 fixation and identify possible strategies for improving the amount of N2 fixed.

Biological nitrogen fixation: investments, expectations and actual contributions to agriculture

The genetic basis of differences in morphology within and between flowering plant species is reviewed in order to elucidate how many genetic changes are responsible for the evolution of new characters. Two broad morphological categories are evident. Differences in structure, shape, orientation, and presence versus absence are frequently discrete and appear to be governed by one or two genes. Differences in dimensions, weight, and number usually exhibit continuous variation and are influenced by numerous genes, though many of them probably act only indirectly via general effects at the whole organ or whole plant levels. Although it is difficult to specify the relative contributions of the two morphological categories during evolutionary divergence, it is clear that discrete character differences are more common in plants than in animals. I propose that their prevalence in plants is a direct consequence of the open, less integrative, and plastic patterns of plant morphogenesis which permit large changes in ...

Genetics and morphological evolution in plants

This review distills recent information on drought resistance characteristics of grain legumes with a view toward developing appropriate genetic enhancement strategies for water-limited environments. First, the possible adaptations that allow grain legumes to better cope with drought stress are summarized. It is suggested that there are considerable gains to be made in increasing yield and yield stability in environments characterized by terminal drought stress by further exploiting drought escape, by shortening crop duration. Many traits conferring dehydration avoidance and dehydration tolerance are available, but integrated traits, expressing at a higher level of organization, are suggested to be more useful in crop improvement programs. Possible genetic improvement strategies are outlined, ranging from empirical selection for yield in droughted environments to a physiological genetic approach. It is suggested that in view of recent advances in understanding drought resistance mechanisms, the latter strategy is becoming more feasible. It is concluded that use of this recently derived knowledge in a systematic manner can lead to significant gains in yield and yield stability of the world's major grain legumes, as they are mainly grown (and will continue to be grown) under rain-fed conditions.

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Strategies for Improving Drought Resistance in Grain Legumes

Publisher Summary This chapter discusses four species of grain legumes of the lowland tropics—that is, peanuts, pigeon peas, cowpeas, and mung beans. Various aspects of these species, such as plant improvement, plant protection, growth processes, and management are described. These four species made up 87% of both the cultivated area and total production on a worldwide basis. Some botanical and adaptive characters of tropical lowland grain legumes are summarized to facilitate direct comparisons of their potential for specific situations. Although species are grouped according to their presumed ecological use patterns, considerable overlap occurs in adaptation and in microclimates of particular locales within regions. The chapter describes various comparative features of tropical species, such as (1) plant types, (2) soil and climate preference, (3) susceptibility to pests and diseases, and (4) yielding ability. To emphasize the positive aspects of growing tropical legumes, a broad array of uses for these crops and their beneficial effects on soil and crops are summarized.

K.O. Rachie

Papers

Grain legumes of the lowland tropics