Cowpea (Vigna unguiculata L. Walp.)

Improving the production and utilization of cowpea as food and fodder.

Advances in cowpea research , Advances in cowpea research , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Advances in cowpea research

Cowpea is an important grain legume throughout the tropics and subtropics, covering Asia, Africa, and Central and South America, as well as parts oi" southern Europe and the United States of America. The use patterns, seed preferences, and cropping systems vary from region to region. Insect pests, diseases, nematodes, parasiticweeds, and drought are major production constraints. Early maturity is preferred everywhere so that cowpeas can be grown in the niches of cereal-based cropping systems, but mediumand late-maturing varieties, with and without photosensitivity. are also required in some regions, to suit the prevalent cropping systems and meet grain and fodder needs. Considerable progress has been made during the past decade in cowpea breeding, and a range of varieties has been developed, combining diverse plant type and maturity with resistance to several diseases, insect pests, and parasitic weeds. Improved varieties have also been developed for grain and fodder and for intercropping with maize, cassava, yam. mil le t , and sorghum for the benefit of smallholder farmers who practice intercropping and use little or no inputs. Introduction Cowpea. Vigna iingiiicidaia [L.] Walp., is an important food legume and a versatile crop cultivated between 35 °N to 30 °S of the equator, covering Asia and Oceania, the Middle East, southern Europe, Africa, southern USA, and Central and South America (Fery 1985, 1990; Mishra el al. 1985; Singh and N'tare 1985; Watt et al. 1985; Heij 1987; Hadjichristodoulou 1991a,b; Perrino et al. 1992, 1993). However, being a drought-tolerant crop with better growth in warm climates, cowpea is most popular in the semiarid regions of the tropics, where other food legumes do not perform as well. Cowpea has the unique ability to fix nitrogen even in very poor soils (pH range 4.5-9.0, organic matter < 0.2%, and a sand content of > 85%). Also, it is shade-tolerant and, therefore, compatible as an intercrop with a number of cereals and root crops, as well as with cotton, sugarcane, and several plantation crops. Coupled with these attributes, its quick growth and rapid ground cover have made cowpea an essential component of sustainable subsistence agriculture in marginal lands and drier regions of the tropics, where rainfall is scanty and soils are sandy with little organic matter. At the same time, if early-maturing erect/semi-erect varieties are grown as a pure crop with required inputs, cowpea has the potential of yielding as high as cereals on a productivity per day basis (Singh and Sharma 1996). 1. International Institute of Tropical Agriculture (IITA). Kano Station, Sabo Bakin Zuwo Road. PMB 3112. Kano. Nigeria. 2. Department of Horticulture. 301 Funchess Hall, South College Street. Auburn University, Auburn, AL 36849, USA. 3. Indian Agricultural Research Institute. Pusa, New Delhi 110012, India.

Recent advances in cowpea breeding

The soybean aphid (Aphis glycines Matsumura), a new pest of soybean [Glycine max (L.) Merr.], rapidly spread throughout North America after its arrival in 2000 and caused millions of dollars in economic losses. At present, the application of insecticides is the only means to control the soybean aphid. However, genetic resistance to the aphid was recently discovered in soybean germplasm and the soybean cultivar Dowling was identified as having strong antibiosis-type aphid resistance. The objective of this study was to determine the inheritance of resistance to the soybean aphid in Dowling. Resistance in F1 ,F 2, and F2–derived F3 (F2:3) families from crosses between Dowling and the two susceptible soybean cultivars Loda and Williams 82 was analyzed. All F1 plants were resistant to the aphid. Heterogeneity of segregation of F2 plants in 14 Dowling 3 Loda F2 families was nonsignificant (P 5 0.16), and pooled F2 data, with 132 resistant to 45 susceptible plants, fit a 3:1 ratio (P 5 0.90). F2 plants from Dowling 3 Williams 82 segregated 135 resistant to 44 susceptible, also fitting a 3:1 ratio (P 5 0.89). Segregation among the F2:3 families fit a 1:2:1 monogenic inheritance pattern. These results indicated that a single dominant gene named Rag1 controlled resistance in Dowling. The monogenic dominant nature of resistance will enable breeders to rapidly convert existing susceptible cultivars to resistant cultivars using backcrossing procedures.

A Single Dominant Gene for Resistance to the Soybean Aphid in the Soybean Cultivar Dowling

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B. B. Singh

Papers

Inheritance of Resistance to Aphid in Cowpea1