Effects of Cultivar and Planting Arrangement on Eggplant Yield in Missouri

Lewis W. Jett1*

Department of Horticulture, University of Missouri, Columbia, MO 65211-7140. Introduction: Eggplant (Solanum melongena L.) is native to India and China and is botanically related

to other solanaceous vegetables such as tomato, pepper, pepino and potato. As consumers

desire more diverse vegetables, many producers in the Midwest have noted an increase in

demand for eggplants, especially the “nontraditional” or specialty types.

Eggplant is typically established as a single row planting arrangement in the Midwest.

However, using a twin row may increase marketable yields. The objectives of this

research were to evaluate eight specialty eggplant cultivars planted in either a single or

twin row planting arrangement.

Methods:

Eight eggplant cultivars were chosen for evaluation (Table 1).

Table 1. Eggplant cultivars evaluated in Columbia, MO-2005.

Cultivar Days to

maturityz

Fruit appearance Seed Vendor

Caliope 64 White/purple; oval Johnny’s Seeds

Ghostbuster 70 White; oval Seigers Seeds

Millionaire 60 Elongated black Seigers Seeds

Megal 64 Slender; black Seigers Seeds

Nadia 67 Purple/black; oval Seigers Seeds

Orient Charm 65 Pink/white; elongated;

Oriental

Johnny’s Seeds

Rosa Bianca 73 Round, Italian heirloom Johnny’s Seeds

Tango 60 White; cylindrical Johnny’s Seeds zDays from transplanting.

1State Vegetable Crops Specialist; Phone 573-882-7511; Email: JettL@Missouri.edu.

* To whom correspondence should be addressed.

Eggplants were seeded in 50-cell trays filled with ProMix media and placed in a

greenhouse. The transplants were fertilized weekly with 600 ppm of nitrogen. Six weeks

after seeding, the plants were transplanted on 5 June 2005. Research was conducted at

the University of Missouri Bradford Farm located near Columbia, MO. Prior to planting

the soil was tilled and pressed into a raised bed (6” height x 26” width). White on black

plastic mulch and drip irrigation was placed over each bed using a Model 2600 mulch

layer (Rainflo Irrigation, East Earl, PA). Plants were spaced either as a single row with

18 inches between individual plants or as a staggered twin row with two rows per bed, 18

inches between rows and between individual plants. Beds were centered 48 inches apart.

Each plot was 15 feet long and contained either 10 plants (single row) or 20 plants

(double row). The experiment was replicated three times in a randomized complete block

design.

Prior to transplanting, 50% of the required seasonal nitrogen (50 lbs/acre) and all the

recommended phosphorus and potassium were top dressed as a granular fertilizer (13N-

13P-13K) to the raised beds. The remaining nitrogen .was injected weekly through the

irrigation system starting one week after transplanting (5 lbs N/acre/week). The

eggplants were staked to keep the fruit off the ground and improve fruit shape. Flea

beetles and cucumber beetles were controlled with Admire insecticide (18 oz/acre)

applied immediately after transplanting. Spider mites were controlled with Capture (5.2

oz/acre) and Acramite 50WS (0.75 lb/acre). No herbicides or fungicides were applied.

Harvest commenced on July 21. The eggplants were harvested weekly for six weeks.

Fruit were harvested that had glossy, tender skin. Each fruit was cut from the plant with

clippers, weighed and examined for quality.

Figure 1. Eggplant fruit was harvested at peak quality.

Results:

Table 2. Marketable yield and number of eggplants as affected by cultivar and planting Arrangement.-Columbia, MO 2005.

Marketable yield Cultivar Row type lb/plant Bu/acrez Fruit/plant Fruit/acre

Culls (lb/plant)

Caliope Single 5.0 1102a 17 124872a 0.7 Twin 2.4 1074a 9 131164a 0.2 Ghostbuster Single 4.3 948ab 10 68728cd 2.0 Twin 2.0 882ab 4 61952cd 0.2 Megal Single 3.8 845a 11 78892bc 1.4 Twin 2.3 992a 7 97768bc 0.2 Millionaire Single 3.1 681ab 12 86636ab 2.5 Twin 2.3 1003ab 8 117128ab 0.2 Nadia Single 4.4 972a 9 61468cd 1.4 Twin 2.7 1163a 5 73568cd 0.3 Orient Charm Single 3.1 689b 10 74536bc 1.9 Twin 1.6 698b 7 95832bc 0.2 Rosa Bianca Single 4.9 1075a 8 60500d 1.4 Twin 2.2 945a 3 50336d 0.2 Tango Single 3.7 820b 12 86152bc 2.2 Twin 1.9 838b 6 93412bc 0.2 Significancey Cultivars NS * * * * Row type * NS NS NS * zA bushel of eggplants = 33lbs. ySignificant * at P =0.05. Means with different letter superscripts are significantly

different at P ≤0.05.

Cultivar Performance:

‘Caliope’ is a purple and white streaked, Indian-type eggplant with no spines on the calyx

(fruit cap). Yield of this cultivar was very good (>1000 bushel/acre) with excellent fruit

size (5 oz/fruit). ‘Rosa Bianca’ is a round, Italian-type eggplant with excellent fruit size

(9 oz/fruit). ‘Rosa Bianca’ thrives in hot weather and does not tolerate cool weather.

‘Nadia’ is an attractive dark purple, Italian-style eggplant that tolerates cool weather.

However, ‘Nadia’ has some spines on the calyx. ‘Megal’ is a purple to black, elongated

eggplant (5oz/fruit) with good yield. ‘Megal’ has spines on the calyx. Ghostbuster’

produced excellent yield of egg-shaped, white fruit (6 oz/fruit) with an attractive, green

calyx. ‘Millionaire’ is a dark purple, elongated fruit. Fruits averaged 4 oz/fruit.

‘Millionaire’ planted as a single row had a significantly higher amount of cull fruit

primarily due to sunscald damage. ‘Millionaire’ did not produce a large plant which

would have shaded the fruit from solar damage. ‘Tango’ is an early, white-skinned

eggplant, but did not yield as well as ‘Ghostbuster’. ‘Orient Charm’ is an elongated

Oriental-type eggplant with a fusion of pink and white streaks. ‘Orient Charm’ has a

very attractive fruit (4.5 oz/fruit), but should be staked for maximum fruit yield and

quality..

Planting Arrangement:

Twin rows doubled the area plant population. Planting the field as single rows has 7260

plants/acre while a twin row arrangement has 14520 plants/acre. Yield per plant

decreased with increasing plant population (Table 1). The twin row did not consistently

increase yield per acre even with a larger number of plants.

Planting arrangement did not affect fruit set per plant. However, with a larger plant

population, twin rows produced more fruit per acre relative to a single row. The

individual fruit weight was less with a higher plant population. Since single rows had less

fruit per acre and less canopy shading, the cull weight was higher. The majority of culled

fruit was late season cucumber beetle feeding damage and sun scalded fruit.

The decision to use a single or twin row for eggplants should hinge on the marketing

method. If eggplants are sold by weight (bushels), a single row of a vigorous cultivar

will produce excellent yields. However, if eggplants are being sold by the count, a larger

plant population with twin rows may be the best choice.

Acknowledgements:

The author wishes to thank Mr. James Quinn and Chris Prenger for assistance in data collection.