Plastic Rowcovers Research Articles

Soil Heating and Secondary Plant Covers Influence Growth and Yield of Winter High Tunnel Spinach

High tunnel (HT) winter production may be limited by extreme low air temperatures, suboptimal soil temperatures, large diurnal temperature changes, and short daylengths and associated low light conditions. To determine the productivity of spinach in extreme climates, HT production trials were conducted in the fall (October to December) and winter (January to March) of 2010–12 at the Greenville Research Farm in Logan, UT (lat. 41 N. elevation 1455 m). Soil heating (±) using electric cables and secondary covers (fabric rowcovers and plastic low tunnels) were evaluated to determine combined effects on fall and winter spinach production. Soil heating significantly increased yield in all cover treatments in the Fall 2010 (F2010) trial when spinach was planted in November, but had little to no effect on plant productivity in the other three trials (more appropriate planting dates) even though it did increase soil temperature marginally. The addition of secondary covers significantly increased plant biomass and leaf area when compared with the uncovered control. Excluding the F2011 trial when spinach was planted earlier under more favorable temperature and light conditions, the use of low tunnels resulted in significantly higher spinach yields (biomass and leaf area) than when grown under fabric rowcover. In the fall, relative growth rates (RGRs) decreased exponentially regardless of whether the soil was heated or not heated or if a secondary cover was used. This response was because of the seasonal decline in light levels and temperatures. In the winter production cycle, spinach relative growth without covers was similar or increased as climatic conditions improved. For plants grown under fabric or plastic rowcovers, RGR remained more constant or decreased during the production cycle. Increased yields were possible with secondary covers as air temperatures increase more quickly in the morning, maintained optimal temperatures longer each day (higher growing degree hours), and retained trapped heat later into the evening. Statistical interaction between heating cables and secondary covers were rarely observed. Fall and winter HT spinach production increases when further protection with secondary plant covers is provided; however, supplemental soil heating is not necessary.

Effects of Three Production Systems on Muskmelon Yield and Quality in New England

Muskmelons (Cucumis melo L.) are routinely grown on black plastic mulch, as the associated increase in soil temperatures, more stable soil moisture, and decreased weed competition result in higher yields than in bare soil production. However, mulch does little to moderate air temperature, which can be below optimum for melon production under New England conditions. One option for increasing air temperature is to grow plants in unheated hoophouses, or high tunnels. Another option is to use low tunnels consisting of ventilated clear plastic rowcovers supported over wire hoops. This study compared low tunnels and high tunnels to open field production for muskmelon production in a peri-urban market farm system in Rhode Island. Five hybrid muskmelon cultivars were grown for 2 years to compare earliness, yield, and fruit quality among the three production systems. Both tunnel systems increased the rate at which growing degree-days (GDD) accumulated relative to open field production, and resulted in statistically significant differences in starting date of first harvest, with fruit in the high tunnel treatment ripening first. The high tunnel production system increased yields per hectare in both years relative to the other production systems due to increased planting density, but not due to increased yields per plant. Marketable yields per hectare from the high tunnel system significantly exceeded those from the open field for four out of the five cultivars in 2011, but for only one out of five cultivars in 2012. Marketable yields from the low tunnel system were ≈10% higher than the open field in 2011, and almost double the open field yields in 2012. Fruit from the low tunnels had the highest concentration of soluble solids in both years. The high tunnel production system did not increase yields sufficiently to offset the associated increase in costs of production, suggesting that muskmelon is not a good crop for high tunnel production in New England. In contrast, a yield increase of only 15% would be sufficient to offset the increased costs of employing the low tunnel production system. Low tunnels have the potential to greatly benefit muskmelon production in New England, particularly in years or locations where GDD accumulate slowly.

Production And Composition Of Chinese Cabbage Under Plastic Rowcovers In Southern Spain

SummaryThe effects of plastic rowcovers on the growth and quality of Chinese cabbage (Brassica pekinensis (Lour) Rupr. `Nagaoka 50') were investigated in Granada, southern Spain (latitude: 378. 10 9.21 99 N; longitude: 38.38 9 E; .10 99 elevation: 600.m), for three years. Polyethylene (T1) and polypropylene (T2) covers increased air temperature by 7K and 5K, and soil temperature (5- and 15.cm depth) by 3±4K and 2K, respectively, compared with plots in the open (T0). In contrast, radiation levels in T1 and T2 were reduced by 12% to 16%, respectively. Thus, total shoot fresh weight was 111% (T1) and 108% (T2) greater under rowcovers, and the commercial head weights were 105% (T1) and 96% (T2) greater, and dry weights 21% (T1) and 13% (T2) greater than T0. These differences in plant production were reflected in higher yields under plastic, and a higher proportion of marketable heads (23% in open air compared with 68% and 65% under T1 and T2, respectively). The concentration of soluble sugars and pigments were also lower in the shoot under rowcovers than in plants in the open air. There were only small differences between the two plastic covers. Slightly warmer conditions and less shade under polyethylene compared with polypropylene provided greater plant production, yields and sugar concentrations, but lower pigment concentrations. Growing Chinese cabbage plants under plastic rowcovers in southern Spain increased production without significantly affecting composition.

Temperature in relation to phosphorus nutrition in Chinese cabbage

Chinese cabbage plants [Brassica pekinensis (Lour) Rupr. cv. Nagaoka 50] were cultivated experimentally for two years (1993 and 1994) using a semi‐forcing technique of floating rowcovers, polyethylene (T1), polypropylene (T2), versus no floating row‐covers, control (T0). Five samplings were made, taking four plants per each replication and total phosphorus (P) (Ptotal), inorganic P (Pi), and calculated organic P (Porg) were determined as well as foliar acid phosphatase activity (FAPA). The aerial and root temperatures of the treatments T1 and T2 exceeded those of T0. The Ptotal concentration showed no significant variations with treatment, whereas the Pi concentrations increased in Ti and T2 and Porg decreased in both treatments with respect to T0. The FAPA was influenced a similar way as Pi, raising with temperature. The contents (mg plant‐1) of Ptolal, Pi, and Porg were greater in T1 and T2 than in T0, and this could be due to the fact that the highest temperatures (root and aerial zone) generated by the plastic rowcovers favored the absorption of P, thereby boosting FAPA and the fresh and dry weights, and yield.

176 Effect of Plastic Rowcover on Watermelon Crop

Citrullus vulgaris cv Rocio hybrid F1 was seeded 18 Jan. 1994 and transplanted 1 month later in loam-sandy soil at the experiment station of the Complexe Horticole, 16 km south of Agadir. Watermelon plants grown under perforated plastic rowcover with 800 holes per square meter were compared to the open-field plants. The experiment design used was a randomized block design with two treatments (rowcover and open field) and four repetitions. Rowcover was put at planting and removed 90 days later. Under the rowcover the minimal and maximal temperatures were higher than the ones of the open field by 0.9 to 2.4 and 3 to 6.8 °C, respectively. Soil temperatures at 10-cm depth measured at 7:00 am and 4:00 pm were higher under cover by 1.2 and 2.7 °C, respectively. Early yield of watermelon obtained under perforated plastic rowcover and in open field were 6.55 kg/plant (78.6 t/ha) and 2.45 kg/plant (29.4 t/ha), respectively.

Mineral Nutrient Composition of Green and White Asparagus Spears

Mineral nutrients were determined in green and white `Jersey Giant' asparagus (Asparagus officinalis L.) spears grown in 1991 near Booneville, Ark. Green spears had higher concentrations of tissue N, K, P, S, Na, and Zn; similar levels of Fe, Al, and Cu; and lower levels of NO3 than white spears grown under opaque plastic rowcovers or under sawdust mulch. Levels of Ca, Mg, and Mn were higher in plastic-grown white spears than in those grown in sawdust. The spear tip contained higher concentrations of K, S, and Cu than the butt. Less NO3, Fe, and Al were in the tip than in the butt. Spear distribution gradients for K, Fe, and Cu were linear, whereas S and NO3 gradients were both linear and quadratic. Nitrogen, P, Ca, Mg, Zn, Al, and Mn levels were influenced by spear production method and spear segment.

Evaluation of row covers for overwintering of strawberries under prairie conditions

Plant survival, bloom response and fruit yield following fall application of a plastic row cover, plastic row cover covered with barley straw, conventional straw, and no cover were compared for two strawberry cultivars, Fragaria × ananassa Duch. Bounty and Hecker. Response was highly dependent on weather conditions. Plastic row cover + barley straw provided the best protection in winters with below-normal temperatures and low snowfall, resulting in the highest yields. Plastic row cover advanced blooming dates of both cultivars by at least 6 d over conventional straw mulch. With proper protection, both the day-neutral and June-bearing cultivars tested in this study appear to be viable for commercial production in Saskatchewan.Key words: Strawberries, Fragaria × ananassa Duch., polyethylene row cover, overwintering

Frost Hardiness of Asparagus officinalis L.

Frost damage to `Jersey Giant' asparagus (Asparagus officinalis L.) spears was evaluated in noncovered and black plastic-covered field plots following a spring frost episode. In the noncovered plots, 78% of spears were killed as compared to only 17% under the plastic rowcovers. Laboratory studies using natural frost simulations indicated that the spears of both treatments were frost hardy to -2.8C. Air temperature data in the field plots during the frost episode indicated that spears in noncovered plots were at lower temperatures (-4.0 to -4.8C vs. -2.8C) ≈4 to 5 hours longer than spears under rowcovers. The large difference in the spear-kill may be due to the difference in the combined effect of the degree and duration of freezing to which the spears had been exposed.

Production and Quality of White Asparagus Grown under Opaque Rowcovers

Black and white plastic rowcovers were established over field-grown `Jersey Giant' asparagus (Asparagus officinalis L.). Spears were cut for 7 weeks. Season soil temperatures were lowest under white plastic and highest without plastic covering. Night air temperature under plastic covers was ≈ 1.4C higher than without plastic covering (control), but day air temperature was typically 10C higher under black plastic, with temperatures under white plastic intermediate. Marketable yield (t·ha-1) was improved with the use of plastics as was total yield (P = 0.05), but spear number/ha was similar in all treatments. There was no consistent treatment effect on spear diameter. Average spear weight was higher when under plastic, whereas spear length was reduced compared with uncovered spears. There were no differences among treatments in spear fiber content, but spears grown under plastic covers were higher in soluble solids content, titratable acidity, and nitrate and lower in protein, ascorbic acid, and total phenolics than uncovered spears. Quantitative differences in these constituents were also a function of whether they were from the upper, middle, or lower spear segment. Very little chlorophyll and carotenoids were produced in the absence of light, but there was a chroma (color intensity) difference between spears grown under the two plastics.