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Hang, A.N., D.C. McClary, G.C. Gilliland, and T.A. Lumpkin. 1993. Plant configuration and population effects on yield of azuki bean in Washington State. p. 588-590. In: J. Janick and J.E. Simon (eds.), New crops. Wiley, New York.

Plant Configuration and Population Effects on Yield of Azuki Bean in Washington State

A.N. Hang, D.C. McClary, G.C. Gilliland, and T.A. Lumpkin

  4. Table 1

Azuki [Vigna angularis (Willd.) Ohwi & Ohashi] is an edible legume grown and used for centuries primarily in the East Asian countries of Japan, Korea, China, and Taiwan. Azuki seed is principally used in confectionery products. Seeds are cooked and mixed with varying portions of sugar and other ingredients to produce an which is used as pastry filling in traditional Oriental confections (Breene and Hardman 1989). Demand for high quality azuki seed has been well documented since 1960. Only 5% of the demand for azuki can be met by Japanese growers and seeds imported from other Asian countries do not appear to meet Japan's standards for quality. After several years of testing on the sandy soils of central Minnesota (Cox 1978) and our studies on the silt loam soils of central Washington state, we have concluded that azuki can be produced in the United States. Azuki may be an alternative crop that producers can rotate with small grains and alfalfa. There is limited production information in English available to growers or cultivars adapted to central Washington state growing conditions. Selection, testing and best management practices are needed before large hectarages can be committed to azuki production for the export market. The purpose of this study was to evaluate plant population and/or field configuration best suited for commercial production under irrigation for optimum use of land, solar radiation, and field equipment.


The field experiment was conducted at Washington State University's Irrigated Agriculture Research center, Prosser in central Washington which is 46°15'N, 119°45'W and is 275 m in elevation. This site averages 160 frost-free days and 190 mm of precipitation annually, mostly during the winter months. The plot was on a silt loam soil (coarse-silty, mixed, mesic, Xerollic Camborthids) and no fertilizers were added during the growing season because of nutrient carryover N and P of 105 and 54 kg.ha-1. A randomized complete block split split plot design was used consisting of 3 blocks or main factors, i.e., plant density of 5, 7.5, and 10 cm apart within row; two subplot factors, i.e., 28 and 56 cm row spacings; and four subsubplot cultivars, i.e., 'Erimo', 'Adzuki Express', 'Hatsune', and 'Takara'. Each subsubplot was 2.3 by 6.1 m. The seed bed was deep plowed (25 to 30 cm) as needed, disked and harrowed before applying trifluralin (alpha,alpha,alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine; at a rate of 0.84 kg.ha-1) for weed control. Beans were planted 2.5 cm deep on May 17, 1990. Plots were sprinkler irrigated as needed for optimum growth. Aldicarb 10G [2-methyl-2(methylthio)propionaldehyde O-(methylcarbamoyl)oxime] was applied on July 13, 1990 at the rate of 16.8 kg.ha-1 following dry bean specifications for two spotted-spider mite (Tetranychus urticae L.) control. Plots were hand harvested from randomly selected 1.1 by 2.0 m areas and threshed by a stationary combine for yield calculation.


Monthly temperatures in 1990 were cooler than average in May and October and warmer during the rest of the growing season. Because of the cool weather, seedlings did not emerged until 12 days after planting. Like other dry edible beans, azuki requires warm temperatures to germinate and grow. Azuki was also reported to be sensitive to extreme weather conditions (D. Burke pers. commun.). 'Hatsune' was an early maturing cultivar and was harvested a week to 10 days earlier than 'Erimo' and 'Takara'. 'Adzuki Express' is a late maturing cultivar; a large percentage of pods of this cultivar was green when other cultivars were harvested.

'Erimo', a Japanese cultivar responded very well to row spacing between 18 and 56 cm. It yielded best on 56 cm versus 28 cm row spacing. The highest yield for this cultivar was 3,660 kg/ha at 352,360 plants/ha compared to 2,270 kg/ha from treatment 28 cm row spacing by 7.5 cm. Average yields from the 56 cm row plots and across within row spacing treatments were significantly higher than for 28 cm row plots, 3,530 vs 2,570 kg/ha (Table 1). Close spacing within the row changed the structure of 'Erimo'; plants were taller, and internodes were longer. After one year testing, we found that 'Erimo' performed best at 56 cm row spacing, and it outyielded the narrow row spacing by 950 kg/ha. At the 56 cm row spacing, 'Erimo' yielded best when planted 5 cm apart.

'Adzuki Express', an American cultivar, did equally well when grown in either 28 or 56 cm rows. However, highest yield of 3,230 kg/ha was achieved in treatment 28 by 5 cm or 704,720 plants/ha (plant row spacing interaction was significant at P = 0.06). 'Adzuki Express' is a late maturing cultivar; green pods and high bean moisture were observed at harvest and it may require harvest 10 to 15 days later than 'Erimo'. 'Adzuki Express' had the lowest yield among the 4 cultivars tested.

'Hatsune', an early maturing Japanese cultivar performed best with 28 cm row and produced the highest yield of 4,065 kg/ha at 28 by 5 cm within row spacing (704,720 plants/ha). Average yields of 28 cm row plots were 300 kg/ha higher than those of the 56 cm spacing. 'Hatsune' was the highest yielding among all the tested cultivars.

'Takara', an old Japanese cultivar performed best in 28 cm row versus 56 cm row spacing and yielded 360 kg/ha more beans than those of the 56 cm row plots. Yield of this cultivar was optimum at 3,645 kg/ha with 28 by 7.5 cm (469,814 plants/ha).

We can suggest, on the basis of this first year data, that 'Hatsune' is well adapted to central Washington growing conditions followed by 'Erimo' and 'Takara'. 'Adzuki Express' was the lowest yielding and latest maturing cultivar tested in this location. 'Hatsune' and 'Takara' yield well with 28 cm row spacing while 'Erimo' yielded best at 56 cm row. 'Adzuki Express' did not respond to plant or row spacings tested in this study. Azuki yield in this study was comparable to the other dry edible beans grown in Washington State and was within the range of azuki yield grown in Minnesota (Cox 1978) and in Japan (McClary et al. 1989).


Table 1. Plant configuration and density effects on azuki yield at Washington State University, Irrigated Agriculture Research Center, Prosser, 1990.

Spacing (cm) Yield (t/ha)
Row Plant No. plants/ha
'Erimo' 'Azuki
'Hatsune' 'Takara'
28 5.1 705 2.91 3.23 4.07 3.22
7.6 470 2.27 2.33 3.01 3.65
10.2 352 2.54 2.45 3.03 2.82
Mean 2.57 2.68 3.37 3.23
56 5.1 352 3.66 2.50 2.91 2.86
7.6 235 3.54 2.98 2.97 3.08
10.2 176 3.38 2.65 3.32 2.68
Mean 3.53 2.71 3.07 2.87
Overall Mean 3.05 2.96 3.22 3.05
LSD (0.05) 0.74 0.81 NS 0.65
P: Row spacing 0.01 NS NS 0.08
Plant spacing NS NS NS NS
Row x Plant inter. NS 0.06 NS NS

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