Luffa Research Report

Growth Regulator Effects on Sex Expression of Luffa Sponge Gourd

Todd C. Wehner, and Tammy L. Ellington

Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609

Cucurbit Genetics Cooperative Report 18: 68

Luffa sponge gourd (Luffa aegyptiaca Mill) is increasingly popular in North Carolina for use in cosmetics and cleaning products. We are interested in developing luffa cultivars suited to industry in the southeast U.S. However, most of the cultivars and breeding lines we are working with are monoecious. In order to make hybrid production easier, we would like to make the plants gynoecious. Sex expression of another cucurbit, the cucumber (Cucumis sativus L.) can be altered using growth regulators to increase the percentage of pistillate flowers (1) or the percentage of staminate flowers (2). Our objective was to study the effects of the growth regulator, ethephon, on sex expression in luffa sponge gourd.

Seeds of ‘Fletcher’ luffa were planted on raised, shaped beds in the field on 20 May 1993. Plants were supported by a trellis 1.8 m high. The experiment was a randomized complete block design with 12 replications of 5 plants per plot. Ethephon was sprayed onto seedlings when they reached the first true leaf stage at a rate of 100 mg/L (+4 drops Tween-20) until runoff. Ethephon was applied 1 time (1st true leaf stage) or 2 times (1st and 3rd true leaves), 0 times for the control.

Traits measured were percentage of seeds that emerged as seedlings (counted at the 1st true leaf stage), percentage of the total flowers that were pistillate in the first 20 nodes, total number of fruits per plot at harvest (5 October), and percentage of fruits that were marketable (total – cull – immature) or early (total – immature). Data were analyzed using the general linear models procedure of SAS.

Seedlings treated with ethephon had no change in sex expression (Table 1). If anything, there was a slight (but non-significant) trend for a smaller percentage of pistillate flowers as the number of ethephon applications was increased. In cucumber, ethephon applications used in this experiment would result in plants that had more than 90% pistillate flowers.

The only significant effect observed in this experiment was for a lower percentage of early fruits in the treatment receiving 1 application of ethephon. We were unable to explain that effect, but ethephon may cause some plant injury after application. In conclusion none of the ethephon treatments affected the percentage of pistillate flowers in ‘Fletcher’ luffa. Perhaps sex expression can be modified with different concentrations or numbers of applications of ethephon, or with other growth regulators.

Literature Cited

1. McMurray, A.L. and C.H. Miller. 1968. Cucumber sex expression modified by 2-Chloroethanephoasphonic acid. Science 162:1396-1397.

2. Pike, L.M. and C.E. Peterson. 1969. Gibberellin A4/A7 for induction of staminate flowers on the gynoecious cucumber. Euphytica 18:106-109.

Table 1. Ethephon treatment of luffa sponge gourd for attempted alteration of sex expression.z

No. ethephon % % pistillate Total % %
applications emergence nodes fruits/plot marketable early
0 63 21 10 70 60
1 65 20 10 60 42
2 59 18 11 66 51
Mean 63 20 11 66 51
LSD (5%) 12 7 3 16 14
CV (%) 22 39 29 29 33

z Data are means of 12 replications of 5 plants per plot.