Influence of Gender and Spacing on Weed Smothering Potentials of Fluted Pumpkin (Telfairia occidentalis Hook F.) In Southeastern Nigeria

A two year field study was conducted in 2013 and 2014 at the farms of the Cross River State Agricultural Development Project (CRADP), Calabar (latitude 05°3’ and 04°27’ North and longitude 07°15’ and 09°28’ East), to evaluate the plant gender and spacing effects on the potential use of fluted pumpkin as a smother crop. Fruits were carefully opened, and the seeds extracted, cleaned of the perispemic tissues and air-dried under shade for 72 hours. ‘Large’ seeds from the peripheral portion of each fruit were classified as ‘female’, ‘smaller’ seeds from the middle portions as ‘male’, and a combination of ‘male’ and ‘female’ seeds as ‘mixed’. The seeds were sown in flat-tilled beds; one seed per hole and at the appropriate spacing. ‘Rogue’ plants (suspected off-gender types appearing on plots where they were unwanted) were routinely culled. Treatments were control (melon sown at 1.0 × 1.0 m spacing), and factorial combinations of three pumpkin genders (male, female, mixed) and three plant spacing {0.50 m × 0.50 m (close spacing), 0.75 m × 0.75 m (medium spacing), 1.0 m × 1.0 m (wide spacing)}, laid out in randomized complete block design with three replicates. Seedling emergence, seedling vigor index, vine girth, leaf area index, and fresh shoot weight were significantly higher for female plants, followed by mixed plants, but neither emergence nor vigor were significantly affected by plant spacing. Weed density and dry weight were in the order female plants < mixed population < male plants, indicating a greater smothering ability of female plants. Only widely spaced female Telfairia populations were as effective in suppressing weeds as the melon treatment. Close spacing reduced the leaf area index and vine growth of female plants and to a lesser extent, those of the mixed population, but did not adversely affect the male plants. Percent ground coverage was significantly affected by plant gender, spacing and their interaction, such that at 9 WAP, the area covered by either the female or mixed plant populations was statistically similar to that of the melon (control) treatment, and was in the order: closely-spaced female > melon > medium-spaced female > widely-space female > closely-spaced mixed > medium-space mixed > widely-spaced mixed. The prevalence of members of the Asteraceae (Compositae) family was low in plots with fluted pumpkin relative to the control, suggesting an allelopathic potential of the smother crop which could enhance weed suppression.