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Six experiments were conducted on ‘Genovese’ basil (Ocimum basilicum L.) in Oklahoma to study the feasibility of establishing basil in the field by direct seeding. Variables examined included use of raw seed or pelleted seed, seeding depth, seeding rate, and comparison with transplanting. Direct seeding was done using a hand-pushed planter (first four experiments), a tractor-drawn planter (fifth experiment), or both types of planter (sixth experiment). Plants were destructively harvested by machine. Stands were established successfully using transplants or using raw or pelleted seed with a handpushed planter. Planting at a depth of ’10 mm resulted in lower yields than planting at a depth where seeds barely were covered with soil (’5mm). Seeding rates of’80 seeds/m led to higher final stands and higher yields than those obtained with seeding rates of’30 seeds/m. These studies were not designed to test effects of plant population on basil yield, but data suggest that final stands above the common recommendation of one plant per 30.5 cm in rows spaced 90 cm apart may result in yield increases. Plots direct-seeded with the tractor-drawn planter failed to establish in the fifth experiment. Plants established using pelleted seed with the hand-pushed planter did not differ from plants established by transplanting in cumulative yields in the sixth experiment, even though the transplanting treatment allowed one additional harvest. The lowest cumulative yields in the sixth experiment came from plants established using pelleted seed with the tractor-drawn planter. Thus, direct seeding of basil was successful only with a hand-pushed planter. While direct seeding is a potentially viable alternative to transplanting for basil stand establishment, there is a need to identify a tractor-drawn seeder that can plant basil at the required shallow depth. In the interim, large-scale producers of basil should continue to use transplants to obtain reliable stand establishment. Basil is one of several herbs being studied for production as an extraction processing crop in Oklahoma. Mechanical harvest and high yields will be necessary to produce the volume of fresh product needed to profitably run an extraction facility. Basil is grown primarily from transplants (Nurzy nska-Wierdak, 2002), but the crop can be established by direct seeding (Davis, 1997; Simon, 1995). Producers are interested in direct seeding for basil stand establishment as a possible method to obtain a high volume of product at a lower production cost than might result from the use of transplants. However, direct seeding of basil is considered to be more prone to failure than transplanting due to adverse factors such as climatic variables and soil crusting (Davis, 1997; Nurzy nska-Wierdak, 2002; Sørensen and Henriksen, 1992). We found little evidence of successful direct seeding of basil in the literature. Nurzy nska-Wierdak (2002) and Sørensen and Henriksen (1992) conducted field research on seeded basil, but plots were small and the method of seeding was unspecified. Schader et al. (2005) sowed basil seeds in rows as an intercrop with sea island cotton (Gossypium barbadense L.) using broadcasting by hand. Our objective was to study the feasibility of establishing basil in the field by direct seeding. We examined factors including use of raw seed or pelleted seed, seeding depth, seeding rate, and comparison with transplanting. Materials and Methods Studies were conducted at the Oklahoma Vegetable Research Station, Bixby from 2008 through 2011 on a Severn very fine sandy loam [coarse-silty, mixed (calcareous), thermic Typic Udifluvent]. Raw and pelleted seeds of the cultivar Genovese were obtained (Johnny’s Selected Seeds, Winslow, ME). Pelleted seeds were of size 13.0 and there were 42,770 pelleted seeds per kg. A tractor-mounted rotary tiller was used for preplant tillage. Urea was used as the source of applied nitrogen (N). When urea was applied, incorporation was facilitated by tillage, timely rainfall, and irrigation. Adequate supplies of other macronutrients were available from fertilization of previous trials. No fungicides or insecticides were applied. Weeds were controlled manually and with machine cultivation. Plant water requirements during germination and after crop establishment were met with rainfall supplemented by overhead sprinkler irrigation. Plots were harvested with a compact forage/ greens harvester (Kincaid Equipment, Haven, KS). The machine cut plants with a sickle bar (height of cut is detailed for individual experiments) and conveyed the cut material into plastic totes. Fresh weights were recorded immediately after harvest. Expt. 1. This study was designed to compare raw and pelleted seed at three seeding depths. The desired seeding rate was one seed per 2.5 cm of row length. The hand-pushed planter (Planet Jr., Cole Planter Co., Albany, GA) planted about two raw basil seeds per 2.5 cmof row length at the lowest setting (plate hole 1, 2.4 mm in diameter). This setting was used for raw seed as it was the lowest rate obtainable. A setting of plate hole 13 (Table 1) provided an approximation of one pelleted basil seed per 2.5 cm of row length. Progressively deeper planting was obtained by placing the standard Planet Jr. shoe in either the first, third, or fifth notch from the shoe. In the first notch, the shoe sometimes did not touch the soil and so made no furrow. Although this most shallow setting often simply dropped seeds in the wheel track, the actions of the covering ‘‘wing’’ shoes and press wheel of the planterwere sufficient to cover all but a few of the seeds. Thus the first notch produced an average seeding depth of 5 mm. The third and fifth notches produced seeding depths of 10 and 20 mm, respectively. Seeding took place on 21 May 2008. Plots were 6.1 m long and rows were 0.9 m apart. The experimental design was a randomized complete block with four replications. Initial stands were obtained by counting all plants in each 6.1 m plot on 11 June. Plants were topdressed with 56 kg·ha of N on 30 June. A destructive, once-over machine harvest was done on 13Aug. with an average height of cut of 25 cm. Final stand counts were obtained immediately after harvest. Expt. 2. This study used the same seed type and seeding depth treatments as Expt. 1. A preplant-incorporated application of 28 kg·ha of N was made on 19 May 2009, after which seeding took place. Plots were 6.1 m long and rows were 0.9 m apart. The experimental design was a randomized complete block with four replications. Initial stands were obtained on 8 June. Plants were top-dressed with 28 kg·ha of N on 9 July. A destructive, once-over machine harvest was done on 10Aug. with an average height of cut of 25 cm. Final stand counts were obtained immediately after harvest. Expt. 3. This study was located adjacent to Expt. 2 and received similar soil preparation, plot spacing, and overall culture. Seeding Received for publication 5May 2015. Accepted for publication 1 June 2015. This research was supported in part by the USDA National Institute of Food and Agriculture, project

Feasibility of Direct Seeding for Stand Establishment of Field-grown Basil