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Abstract
The mungbean [Vigna radiata (L.) Wilczek] is an important short-duration annual grain legume. Mungbean is grown principally for its edible dry seeds, which are high in protein, easily digested, and prepared in numerous forms for human consumption; e.g., as a green vegetable and for sprouts. Other attributes of the crop include drought tolerance, high lysine content as compared to cereal grains, low production of flatulence, and wide adaptability. Commercial production occurs throughout Asia, Australia, the West Indies, South America, and tropical and subtropical Africa. In North America, production is centered in northern Texas and Oklahoma. Annual world mungbean production is estimated at 1.4 million t harvested from ≈3.4 million ha (1). In the United States >50 million kg of bean sprouts are produced annually from 8.3 million kg of mungbean seeds (4).
Iron Deficiency Chlorosis (FeDC) is a problem in cowpea because it affects the ability of the plant to produce chlorophyll. Earlier studies indicated that FeDC was conditioned by a single gene. Pinkeye Purple Hull (PEPH), a susceptible variety, and Texas Pinkeye Purple Hull (TXPE), a resistant variety, were crossed and allowed to self for one generation. The F1s were backcrossed to the parents. SPAD readings were taken on each population. SPAD measures the transmission of light through the leaves at a wavelength where chlorophyll absorbs and a wavelength where it does not. The SPAD reading is calculated based on a ratio of these two numbers. Thus, the SPAD value is unitless and is an indication of the relative amount of chlorophyll present in the leaf. Chlorophyll was extracted from leaves, and regressed on the SPAD readings from the same leaves. An R 2 of .9102 was obtained as well as a regression equation of y = 12.8x + 54.5. Thus, a SPAD value of 1 corresponds with a chlorophyll content of ≈67.3 μg chlorophyll/gfw. The data was analyzed using a bootstrap method, and indicated that FeDC is not controlled by a single gene. A P-value of .0004 showed a highly significant difference between the expected and observed segregation ratios in the F2 plants. Narrow sense heritibility (Mather) was estimated at 0.3.