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Anderson, R.G., S. Bale, and W. Jia. 1996. Hyacinth bean: Stems for the cut flower market. p. 540-542. In: J. Janick (ed.), Progress in new crops. ASHS Press, Arlington, VA.

Hyacinth Bean: Stems for the Cut Flower Market

Robert G. Anderson, Sharon Bale, and Wenwei Jia

  1. METHODOLOGY
  2. RESULTS
  3. SUMMARY
  4. REFERENCES
  5. Table 1
  6. Table 2
  7. Table 3
  8. Fig. 1
  9. Fig. 2
Hyacinth bean (Dolichos lablab L., Fabaceae) has been a novelty garden plant in the U.S. for generations (Piper 1915; Bailey 1930). This vigorous, twining vine is characterized by large ternate purple-green leaves and purple petioles. The vines produce hundreds of spikes of lavender flowers in late summer followed by long-lasting deep lavender-purple pods. Hyacinth bean, lablab bean, field bean, sem (India) or pig-ears (Chinese, from the leaf shape) is primarily an ornamental annual vine in the U.S., but it has been used for centuries in India and China as an edible pod and animal forage (Singh and Pandita 1980; Saraswat 1986). The distinctive long-lasting pods are suitable for cut stems for the cut flower industry. In addition, the pods are so unique that they could be used for decoration or harvested for Chinese food wholesalers.

Preliminary studies in 1992, demonstrated high yields, simple production practices and relatively long vase-life for cut pod stems. The objective of this study was to determine the number of cut stems of hyacinth bean pods that could be produced, the seasonal variation in production, the impact of plant density on cut stem production, and the number of pods produced per stem.

METHODOLOGY

Hyacinth beans were planted on 60 lineal meters of fence, 1.5 m tall, for yield trials in 1993 and 1994 at the University of Kentucky Horticulture Research Farm in Lexington. In 1993, three randomized replicates (each 10 m long) were planted with 1 or 3 plants/m. In 1994, plant densities of 0.6 or 1 plant/m were used on the same randomized fence sections. All stems with fruit were harvested when all fruit on a stem were mature enough that the pod was swollen from seed development. This was determined to be best in preliminary vase-life studies. Length of each cut stem and fruit number were determined for each harvest date.

Hyacinth bean seeds were planted May 1 of both years into MetroMix 510 in 10 cm pots and grown in a greenhouse (17° night/25°C day) for 4 to 5 weeks. Plants were fertilized once per week with 100 ppm nitrogen from 20-4-16 fertilizer. Plants were transplanted to the field in the first week of June. Plants were irrigated when necessary during the summer and fertilized monthly, through August. Pesticide applications for grasshoppers were necessary in mid summer both years, but no other insect pests were a problem even though many were present in adjacent fields.

RESULTS

Hyacinth bean is a highly productive plant. Nearly 3800 commercial quality cut stems were harvested from Aug. 20 to Oct. 29 in 1993 with warm Sept. weather (Fig. 1). Yields were reduced to 1800 cut stems in harvests from Aug. 20 to Sept. 10 due to cool Sept. weather in 1994.

Although there was no significant effect of density on stem production per linear meter of row in both years, the highest production was achieved with the denser planting (Table 1). This relationship between plant density and yield was also demonstrated by Singh and Pandita (1980) at higher plant densities.

As plant density increased, cut stem production per plant decreased proportionately (Table 1). Hyacinth bean is a very vigorous vine and individual plants grew to fill the space on the fence. The mean number of commercial quality cut stems harvested per plant was as high as 55 cut stems per plant in 1993. The relatively low plant densities used in this study still did not identify the maximum yield that could occur on a per plant basis. The lowest plant density used by Singh and Pandita (1980) was approximately 1.5 plants/m and had a mean yield of 19 inflorescences per plant.

Cut stem lengths varied from 25 to 90 cm. The percentage of stems in standard cut flower grades were nearly identical in both plant densities in both years (Table 2). In 1993, approximately 60% of the stems were in medium stem length grades (46-55 cm and 56-65 cm) with just over 10% in the long stem length grades. Longer stem length grades were dominant in 1994 because the harvest period was short due to cool Sept. weather. Longer stems were more common in the early harvests than in later harvests in both years so the 1993 harvests included many shorter stems from the later harvest periods.

Over 80% of the total harvest of cut hyacinth bean stems occurred in the first two weeks of harvest in late Aug. in 1993 and 1994 (Table 3). Yields were so high that harvest occurred on 2-3 day intervals for 12-15 days. However, the number of stems harvested dropped quickly after the first two weeks. It was hoped that harvest would occur over 6-8 weeks, but this was not the case.

The number of purple fruit ranged from one to 30 per cut stem. The mean fruit number was nine fruit per stem regardless of plant density within the rows. Singh and Pandita (1980) measured a mean of 13 fruit per stem on supported plants. Approximately 90% of the cut stems had 4 to 12 fruit on each stem (Fig. 2). This number of fruit per stem was appropriate for use as a cut stem in flower arrangements.

SUMMARY

Hyacinth bean cut stems are a unique item for cut flower arrangements. Some local and regional florists enjoyed the special color and texture that hyacinth beans offered their arrangements while others had little interest in use of these stems. With yields as high as 70 cut stems per lineal meter of fence, the potential returns could be quite high [7 bunches/m x $2.50/bunch (a common minimum wholesale price) = $17.50/m] for short term harvest and marketing of this summer/fall crop. However, there is no established market for hyacinth bean cut stems and guarantees of profitability cannot be made.

REFERENCES

Table 1. Mean yield of commercialquality cut stems of hyacinth bean on a per plant and per meter basis.

Mean number of commercial
quality cut stems
Year Plant density
(plants/m)		 Per plant Per m
1993 1 55.6 55.6
3 23.1 69.3
1994 0.6 47.2 28.3
1 31.1 31.1

Table 2. Yield and distribution of hyacinth bean stems based on density in 1993 and 1994.

Distribution of cut flowers (%)
Year Plant density (plants/m) 36-45 cm 46-55 cm 56-65 cm 66-75 cm 76-85 cm 86-95 cm Total yield (60 linear m)
1993 1 24 33 28 11 3 1668
3 27 34 26 10 2 2080
1994 0.6 4 43 31 17 6 1 849
1 3 43 32 17 5 1 932

Table 3. Distribution of harvest of cut hyacinth bean stems based on density in 1993 and 1994.

Distribution of cut stem harvest (%)
Year Plant density
(plants/m)		 Aug. 20 Aug. 30 Sept. 10 Sept. 17 Sept. 24 Oct. 1 Oct. 7 Oct. 29
1993 1 53 29 9 3 2 1 1 1
3 56 31 8 6 1 1 0.5 1
1994 0.6 54 37 9
1 58 34 8

Fig. 1. Contrast in mean daily temperature in 1993 and 1994 during hyacinth bean harvest.

Fig. 2. The distribution of fruit number per stem of all cut hyacinth bean stems in 1993.

Last update August 24, 1997 aw