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- Author or Editor: K.M. Batal x
Various applications of N fertilizer formulations to bell pepper plots were made to affect soil nitrate-N concentrations from 5 to 30 ppm throughout the growing season. Number and weight of marketable grades for the 1st and 3rd harvests were improved by increasing soil N from 5 to 30 ppm. In the final (4th) harvest, marketable yield was highest for applications maintaining soil N of 25 ppm. Earliness was enhanced by N sources with Ca(NO3)2 producing the earliest yield followed by NaNO3 and NH4NO3. Total marketable yield produced by Ca(NO3)2 or NaKNO3 was 3 t/ha higher than by NH4NO3 applications. High marketable quality was maintained with Ca(NO3)2 and NaNO3 treatments. The highest blossom-end rot (BER) incidence was associated with NH4NO3 applications. But the N source effect on BER was strongly influenced by soil nitrate levels. At 10-20 ppm soil N, leaf Ca decreased during the 8 to 12 week period, but at higher soil N, leaf Ca remained unchanged, indicating a constant Ca uptake during the critical growth period.
Commercial N fertilizer formulations, ammonium nitrate, calcium nitrate, sodium nitrate, potassium nitrates (15-0-14 and 13-0-44) applied at 84 and 168 kg N/ha in 3 or 5 split applications did not affect total marketable yield of dry onion. Application frequencies causing an increase in total amount of N applied during the spring months (Feb.-Apr.) increased marketable yield by 5 MT/ha. Bulb decay was the highest when ammonium nitrate was applied, whereas the least number of decayed bulbs resulted from sodium nitrate applications. Plants grown with potassium nitrate (13-0-44) were most susceptible to cold injury. Ammonium nitrate and sodium nitrate applications produced the highest percentage of onions that bolted. The lowest percentage of plants showing bolting incidence resulted from calcium nitrate applications. Bolting of onions was closely associated with rapid growth and increased onion size. However, cold injury and bulb decay were not influenced by these growth factors.
Mixtures of (2-chloroethyl)phosphonic acid (ethephon) plus gibberellic acid (GA3) were applied to ‘Edisto-47’ muskmelon (Cucumis melo L.) plants at the 3–4 true leaf stage for 3 growing seasons. Ethephon at 240 mg/liter + GA3 at 100 mg/liter consistently increased the marketable yield of melons over the control. However, at 480 mg/liter ethephon, increased GA3 concentration from 50 to 150 mg/liter decreased yields. Average fruit weight and lengthdiameter ratios were increased by all ethephon + GA3 combinations, compared to the untreated control. Increased soluble solids and sweetness by 240 mg/liter ethephon + 100 or 150 mg/liter GA3 combinations were associated with increased fruit weight.
The susceptibility of fraser fir (Abies fraseri), canaan fir (A. balsamea var. phanerolepis), and nordmann fir (A. nordmanniana) to phytophthora root rot (PRR) incited by Phytophthora cactorum or P. drechsleri was assessed in two experiments in central Pennsylvania. In an 8-week greenhouse study, seedlings and transplants growing in soilless substrate were inoculated with Phytophthora in flooded and non-flooded settings. In an 8-week outdoor study conducted in raised planting boxes filled with soil, transplants were inoculated with Phytophthora species in well-drained and poorly drained soil. Based on foliar disease ratings, mortality rates, and dry shoot and root weights, differences in susceptibility to P. cactorum and P. drechsleri existed between these true fir (Abies) species. Fraser fir was very susceptible to P. cactorum and P. drechsleri. Canaan fir had strong resistance to P. cactorum and P. drechsleri in well-drained settings but was susceptible in poorly drained settings. Nordmann fir had very strong resistance to P. cactorum and P. drechsleri in both well-drained and poorly drained settings.
The most serious disease problem in fraser fir (Abies fraseri) Christmas tree production is phytophthora root rot (PRR). The efficacies of six fungicide treatments in preventing PRR incited by Phytophthora cactorum and P. drechsleri in 2-year-old fraser fir seedlings were evaluated in 2010 and 2011 in central Pennsylvania. The study examined five fungicide drench treatments [dimethomorph, fosetyl-aluminum (fosetyl-Al), hydrogen dioxide, mefenoxam, propamocarb hydrochloride] and one soil spray treatment (mefenoxam) in raised planting boxes. Dimethomorph applied on 14-day intervals prevented foliar disease symptoms and mortality in fraser fir seedlings exposed to either P. cactorum or P. drechsleri. One-time application of fosetyl-Al or mefenoxam were effective at times in preventing foliar disease symptoms and mortality in fraser fir seedlings exposed to P. drechsleri but were not as effective against P. cactorum.
Ripening of pimiento and paprika peppers (Capsicum annuum L.), tested at 2 locations, was accelerated by (2-choroethyl)phosphonic acid (ethephon) when applied close to normal fruit maturity. Potential chemical ripeners of Buckman Laboratories, BL-2142 (Poly[oxyethylene(dimethylimino)-ethylene(dimethylimino)ethylene dichloride]) and BL-2143 (Poly[hydroxyethylene(dimethylimino)-ethylene(dimethylimino)methylene dichloride]) slightly enhanced ripening of pimiento, but had little or no effect on paprika. Ethephon (1500 to 3000 ppm) applications induced defoliation and fruit abscission in pimiento and paprika, especially at later stages of fruit development. Extractable red color of dehydrated paprika was improved by ethephon and BL-2143 at 1000 mg/liter.
In field experiments, yields of pepper (Capsicum annum L.) were obtained by more frequent irrigation, nitrogen topdressings, and increased plant population. The highest marketable yield resulted when sufficient N was added to maintain soil NO3–N levels between 20 (spring) and 30 (fall) ppm. In both seasons, the number of N topdressings was doubled in order to raise the soil NO3–N maintenance levels from 10 to 20 ppm or from 15 to 30 ppm. Yield increases were influenced by frequent irrigation only when additional N was applied to maintain a higher soil NO3–N. Populations greater than 27,000 plants/ha increased marketable yields in spring and fall by 2.8 and 7.1 MT/ha respectively.
The effects of three rates of N, Mg, and B on cauliflower (Brassica oleracea, Botrytis group) yield, average curd mass, and hollow stem disorder were evaluated on sandy and clay loam soils. Cultivars White Empress and Stovepipe were tested on the sandy loam soil and `White Empress' was tested on the clay loam soil. Maximum mean curd mass and maximum yields were obtained with the highest N rates (269 and 381 kg·ha-1) applied to sandy loam and clay loam soils, respectively. Yield response to increased N rates varied with cultivar. Increasing Mg from 22.5 to 90 kg·ha-1 did not affect yield or curd mass on clay loam soil, but increased yield and mean curd mass on sandy loam soil. The Mg effect on curd mass was influenced by N and B rates. On both soil types, the higher Mg and B rates reduced the incidence of hollow stem, but the Mg effect was influenced by N applications. On clay loam soil, increasing B from 2.2 to 8.8 kg·ha-1 reduced hollow stem but had no effect on yield or curd mass. On sandy loam soil, B at 4.4 kg·ha-1 maximized yield and curd mass, but the hollow stem disorder continued to decrease as B rates were increased from 2.2 to 8.8 kg·ha-1.
Germinated seeds of pepper (Capsicum annuum L.) were fluid drilled in loamy sand and sandy soils on 5 sowing dates with additives daminozide, diphenamid, gibberellic acid, phenamiphos, and metalaxyl. Two sets of greenhouse transplants were produced from germinated seeds. The plants of the first set (T1) were transplanted in the field at the time of field seeding. The second set (T2) was greenhouse seeded on the field sowing dates and was transplanted later in the field. Gel additives did not affect total fruit yield. The T1 transplants produced significantly higher total yields than did the field-seeded crop. However, yields from these transplants were equal to or less than those from the field-seeded crop when the yields from the first 6 harvests were compared on Tifton loamy sand. Yields from the T2 transplants were similar to those obtained by field sowing. Yields in loamy sand were higher than those in sandy soil at all plantings for all treatments.
Stress-strain measurements of the skin from fruit of 5 tomato cultivars were related to field data for fruit cracking. No relationship was found between modulus of elasticity and fruit cracking, but ultimate force and breaking elongation showed inverse relationships to fruit cracking. Breaking elongation, which reflects both elasticity and plasticity of the skin, should be of value in estimating crack resistance of tomato fruit. The Instron instrument was used to determine these mechanical properties.