Influence of Plant Spacing on 'Connecticut Field' Pumpkin Size, Density, and Yield

Robert J. Dufault and Ahmet Korkmaz

Clemson University, Coastal Research and Education Center, Charleston, SC 29414

Additional index words. pumpkin, cucurbitaceae, population, Cucurbita pepo, volume, quality, handles

Abstract. The distance between rows was 6, 9, or 12 ft (1.83, 2.74, or 3.66 m) apart. The distance between plants within rows was 3, 6, 9, or 12 ft (1.83, 2.74, or 3.66 m) apart. Plant populations ranged from as few as 303 plants/acre (758 plants/ha) to 2,420 (6,050 plants/ha) plants/acre. Plant spacing had no significant effect on color, handle quality and shape of marketable pumpkins, but as plant populations increased from, pumpkin weight tended to remain unchanged, while the volume approximately doubled and the density decreased. Marketable yield was best for any row spacing that combined a 3-ft spacing between plants within the rows (for example 6 ft between rows and 3 ft within the row; 9 x 3 ft; and 12 x 3 ft). The highest yielding systems, however, were plants in 12 ft rows and 3 ft between plants within the rows, followed by the 9 x 3 ft system and lastly the 6 x 3 ft spacing system. The heaviest and densest pumpkins of these three spacings occurred with the 12 x 3 ft spacing, averaging 9.4 lb (4.26 kg) with the least number of culls and field rots.

Pumpkins for U-pick pumpkin patches are increasing in frequency in the south-eastern U.S. The production of pumpkins for Halloween must begin in midsummer when temperatures are extremely high in this region. Maturation of pumpkins occurs in September and October when field conditions are still considered very warm and not conducive for pumpkin growth and development. Often the pumpkins attain acceptable size yet their density is very low and unacceptable. It is unknown what the ideal plant population and spacing are to enhance maximum size, density and numbers of pumpkins per acre. The 1997 pumpkin spacing trial at Clemson University's Coastal Research and Education Center contrasted 12 treatments varying in row spacings (between rows and within rows). The objective of the study was to determine an ideal spacing that would maximize numbers of marketable pumpkins per acre and pumpkin quality (shape, size, color, weight, and density).

Materials and methods

The distance between rows was 6, 9, or 12 ft apart. The distance between plants within rows was 3, 6, 9, or 12 ft apart. Plant populations ranged

from as few as 303 plants/acre to 2,420 plants/acre. The open-pollinated variety, Connecticut Field, was selected because it usually produces an ideal jack-o-lantern-type pumpkin that consumers like. Transplants were seeded in the greenhouse 23 June 1997 and field planted 9 July. Each cultural system included three rows aligned side by side with a total of 18 plants within each three-row plot. One ton of lime and 1 ton of 10­10­10/acre were incorporated in beds before mulching with black plastic. Fungicides and insecticides were applied weekly until 25 Sept. with complete harvest on 1 Oct. All pumpkins were cut from the vine, weighed and graded. Field rots were also counted on 1 Oct. During the pumpkin production season, there were 24.4 inches of rain. At harvest, each pumpkin was weighed, and length and width measured for density estimation.

Results and discussion

Plant spacing did not significantly affect color, handle quality and shape of the marketable pumpkins, but there were some interesting and important trends on density, volume and weight. The most notable was that as plant populations increased from low (303 plants/acre) to high (2,420

Cucurbitaceae '98


Table 1. Yield and quality of 'Connecticut Field' pumpkins grown using different between and within row spacings.

Spacing Marketable pumpkins

between Plants/ No./acre Wt Vol Density

rows plants acre Marketable Cull Field rots Total (lb) (in3) (oz/in3)

6 3 2,420 670 536 581 1,787 6.7 1,214 0.09

6 6 1,210 268 201 179 648 6.7 942 0.11

6 9 807 293 103 402 798 6.6 617 0.21

6 12 605 528 110 264 902 6.3 923 0.11

9 3 1,613 712 119 771 1,602 6.5 1,060 0.10

9 6 807 352 103 191 646 8.0 1,132 0.12

9 9 538 300 126 309 735 6.6 1,147 0.10

9 12 403 279 95 330 704 6.6 764 0.14

12 3 1,210 781 67 134 982 9.4 993 0.15

12 6 605 198 110 187 495 6.7 891 0.12

12 9 403 271 95 176 542 6.7 688 0.16

12 12 303 181 48 80 309 7.8 675 0.21

 

plants/acre), pumpkin weight tended to remain unchanged, yet the volume approximately doubled, but the density decreased (Table 1). Translated, as populations increased, the pumpkins grew larger, but these larger pumpkins could be perceived as lighter and airy.

Marketable yield was best for any row spacing that combined a 3-ft spacing between plants within the rows (for example 6 ft between rows and 3 ft within the row; 9 x 3 ft; and 12 x 3 ft) (Table 1). The highest yielding systems, however, were planted in 12 ft rows and 3 ft between plants within the rows, followed by the 9 x 3 ft system and lastly the 6 x 3 ft spacing. The quality of the pumpkins at these three spacing schemes were all acceptable; however, the heaviest and densest pumpkins of these three spacings occurred with the 12 x 3 ft spacing, averaging 9.4 lb (4.26 kg). The 12 x 3 ft spacing scheme produced very few culls and field rots.

'Connecticut Field', an open-pollinated vari

ety, displayed lots of variability in fruit size and shape. It is expected, however, that hybrid cultivars might respond differently to spacing. With 'Connecticut Field', I did not find that spacings wider than the 12 x 3 ft spacing (1,210 plants/acre) produced the desired package of many large and dense pumpkins. Another advantage of the 12 x 3 ft spacing over the 6 x 3 ft and 9 x 3 ft spacings is the need for fewer transplants than closer planting schemes.

In 1997, all plant spacings received the same amount of preplant fertilizer, which may have limited pumpkin weight, density, volume and yield. The failure of closely spaced schemes to produce larger numbers of dense, heavier pumpkins may have been caused by the greater nutritional demands of more plants in a unit area. In 1998, attempts will continue to improve quality and yield of closely spaced pumpkins by evaluating the nutritional demands of plants growing under greater competition.

Cucurbitaceae '98