Regina P. Bracy

Field Incineration of Plastic Mulch

ABSTRACT A machine to incinerate plastic mulch as it is pulled from a soil bed has been designed, built, and tested. The machine incorporated automatic pickup speed control and liquified petroleum (LP) gas burners to attempt to incinerate the plastic mulch as it was removed from beds in strawberry and bell pepper production fields. The machine did not incinerate the plastic mulch completely, but melted the plastic mulch into globules. The incinerating machine required more operator lime than manual removal or a mulch collector machine tested previously.

Bed Height for Greens Crops

ABSTRACT A field study was conducted to determine the optimum bed height for leafy greens crops grown on shaped beds. Bed heights of 5, 10, 15, and 20 cm (2, 4, 6, and 8 in) were evaluated with crops of mustard (Brassica juncea [L.] Czerniak.) and turnip (Brassica rapa L. Rapifera group) during three crop seasons. Few significant differences in stand count, yield, or product quality resulted from the different bed heights. A trend toward lower yields, quality, and reduced efficacy of precision cultivation was noted with the 5-cm (2-in) bed height.

Optimum N and P rates for greenhouse production of vegetative coleus using constant liquid feed

ABSTRACT Many new coleus (C. hybridus cv.) cultivars are vegetatively propagated and require different fertilization practices from seed propagated cultivars. Two experiments were conducted to evaluate growth responses of Henna, Indian Summer, Mint Mocha, New Orleans Red, Red Head, and Trusty Rusty to 0, 70, 140, 280 and 420 mg·L−1 nitrogen (N), and Henna, Mint Mocha, Red Head, and Trusty Rusty to 0, 6.2, 12.4, 24.8, or 49.6 mg·L−1 phosphorus (P) to determine optimum constant liquid feed rates to produce marketable size plants from rooted cuttings. Positive growth responses in terms of biomass were found with increasing N rates but not P rates. For medium-sized cultivars such as Henna, Indian Summer, and New Orleans Red, quadratic responses were found in aboveground biomass, and N at 280 mg·L−1 resulted in similar plant size and dry weight as those fertilized at 140 and 420 mg·L−1 N. For large-sized cultivars such as Mint Mocha, Red Head and Trusty Rusty, plant dry weight responded linearly within the N range tested and were greatest at 420 mg·L−1. However, plant visual quality was negatively affected by N rates at 280 and 420 mg·L−1 in that, leaf color became less intense at these high N rates. Plants fertilized at 70 mg·L−1 were smaller than those fertilized at 140 mg·L−1, however, they received similar visual quality ratings because of more intense leaf color. Therefore, N at 70 to 140 mg·L−1 can be used to grow most vegetative coleus for similar marketable quality. Mint Mocha and Henna were the only cultivars responded to P treatments that, 12.4 mg·L−1 P rate resulted in greater biomass than the no-P control. All other cultivars had no response to supplemental P except a linear response in tissue P%. Therefore, supplemental P is not required during the 8 week production period when there is an initial P charge in the substrate. We found that substrate pH decreases with higher P rates, therefore supplemental P fertilizer can be used for adjusting pH. Both N and P rates found optimum in this study are lower than current industry practices (N at 150 to 250 mg·L−1 and P at 24 mg·L−1) and can significantly lower production cost and potential leaching of excessive nutrient into waterway. Nutrient treatments in further study on postharvest performance of vegetative coleus will be selected based on this study.

Broadcast vs. Band Fertilizer Applications on Summer Squash

ABSTRACT Three methods of preplant fertilizer application (broad-cast-and-bed, bed-and-broadcast, and bed-and-band) and two methods of sidedress fertilizer application (broadcast and band) on zucchini and yellow straightneck summer squash (Cucurbita pepo var. melopepo [L.] Alef.) were compared. With crops planted in late spring and early summer, no differences in yield due to sidedress method and few differences due to preplant application method were found. A trend toward lower yields with the bed-and-broadcast method was noted. No yield loss resulted when the more cost-effective broadcast method was used for preplant or sidedress fertilizer application to summer squash if the preplant broadcast application was made prior to the bedding operation.

Seeding rate affects root production of turnip (Brassica rapa L. (Rapifera group)).

ABSTRACT Field studies were conducted in the spring and fall 1997 to evaluate the effects of seeding rate and plant population on yield and grade-out of turnips grown for root production. Open-pollinated and hybrid turnip cultivars were planted with a belt-type precision seeder at 56, 112, 168 mm in single- or double-plant lines per row and with a bulk seeder set at the smallest opening (average seed spacing of 51) utilizing 100% viable seed or 50% viable seed/50% killed seed (by weight) mix. Overall, total yield was not affected by seeding rate or seeder; however, plant population produced a shift in yield among grades. Generally, yield of extra-large roots was greatest on plots with lower plant populations. Medium and cull yields were greater on plots with the higher plant populations (bulk seeder with 100% viable seed and precision seeder with 56-mm spacing or 2-row configuration). Yield of culls increased as plant population increased. Results from using a bulk seeder with 100% or 50% viable seed were inconsistent.

Rolling Beds After Precision Planting Enhances Bed Integrity at Harvest

The use of a spool-type roller immediately after precision planting resulted in a flatter, smoother bed surface that facilitates mechanical harvest of greens crops. Rolling also reduced bed erosion by eliminating the presswheel furrows that tend to channel and accumulate rainwater on the tops of the beds. Rolling did not affect stand or yield of greens crops or cabbage.