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Anastacio Perez Naranjo and Robert J. McNeil

The experiment compared productivity and vegetative growth of the Hass avocado on three avocado root rot resistant rootstocks and one susceptible rootstock. Hass trees on Duke 7 reported the largest number of fruit per tree and on G 755c the smallest five years after planting. Trees on Topa Topa and Duke 7 reported the highest average production four years after planting. Trees on G 755c were significantly lower in the amount of leaf N. Trees on Toro Canyon and G 755c showed significantly lower amounts of Na. Trees on Duke 7 showed a significantly higher level of Mn. Trees on G 755c were significantly smaller two years after planting. Trees on Topa Topa and Duke 7 showed a significantly larger canopy diameter than those on G 755c four years after planting. Trees on G 755c showed the smallest mean shoot growth four years after planting. Trees on G 755c had significantly larger trunk circumferences three and four years after planting. No statistical differences were found among rootstocks as to freeze damage to the Hass scions.

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V.M. Russo and J.C. Díaz-Pérez

Heat stress can limit yield in pepper (Capsicum spp.), generally through flower and fruit abortion. A kaolin-based particle film, originally developed to protect fruit trees from insects, has been found to reduce temperatures in tissues of plants. A kaolin-based particle film was tested to determine if it could be used to improve yields of pepper in Oklahoma and Georgia. In Oklahoma, seedlings of a bell pepper, `Jupiter', and a nonpungent jalapeño, `Pace 103', were transplanted at three progressively warmer planting dates from mid-May to mid-July 2002 and 2003, that would ensure that inflorescences would be subject to high day and night temperatures and treated with the kaolin-based particle film. Applications were begun as the first flowers were set and continued through the settings of the first three flushes of flowers on a three-times a week schedule, or on an as needed basis, to determine if the kaolin-based particle film improved yield. In Georgia, the bell peppers `Camelot' and `Heritage VR' were transplanted on 24 Apr. 2003, and treated with the kaolin-based particle film. In addition to yield, physiological measurements and disease incidences were recorded in Georgia. In both locations treatment with water only served as controls. In Georgia, the kaolin-based particle film had no significant effect on net photosynthesis, stomatal conductance, leaf transpiration or leaf temperature, as measured at midday on clear days. In Oklahoma, planting bell pepper after 15 May is not recommended. Planting the nonpungent jalapeño after mid-June can reduce yields. The kaolin-based particle film did not affect yield at either location and is not recommended for use on peppers.

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Philip J. Kauth and Hector E. Pérez

Native plant sales have increased steadily during the past decade because of consumer concern with invasive plant sales, water conservation, and land management issues. However, native plants are still under-used mostly because of a small market and the lack of education on the use and care of native plants. For example, native plant sales in Florida accounted for only 11% of the total horticultural market in 2005. Within the Florida native plant industry, a small, but competitive market focuses on native wildflowers, but a paucity of information related to opportunities within this segment exists. We sent surveys to 137 members of the Florida native plant industry to learn about their interests, concerns, and trends in the native wildflower market. Survey respondents identified low demand, seed supply, and availability of desired species, plus insufficient customer and industry education as major factors limiting Florida native wildflower (FNW) sales. An overwhelming majority predicted that sales for locally produced FNWs would increase over the next 5 years. Respondents also stated that seed germination, seed storage, and seed production research are vital for the advancement of the industry. This survey provides an excellent opportunity to analyze the current native wildflower market and identify areas to help increase awareness of FNWs.

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J. Farias-Larios, M. Orozco, S. Guzman, and J. Perez

This work was conducted for evaluate the influence of clear and black polyethylene mulches, used alone or combined with floating rowcover (FRC) and plastic perforated microtunnels, on insect populations, growth and yield of muskmelon. Treatments evaluated were 1) clear plastic + FRC, 2) polyethylene perforated microtunnel, 3) clear plastic + polyethylene not perforated microtunnel, 4) black plastic + FRC, 5) clear plastic, 6) black polyethylene, 7) clear plastic + oil, and 8) bare soil. Aphids and sweetpotato whitefly adults and nymphs were completely excluded by floating rowcovers while the plots covered. The export and national quality fruit yield was major in the mulched beds in relation to control. Clear polyethylene mulch + FRC increased number of fruit and export marketable fruit of cantaloupe (45.2% and 44.8%) with respect to black plastic + FRC, respectively. It is proposed that, under tropical conditions and under high insect stress, mulches combined with floating rowcovers should be selected for their effects on insects in addition to their effects on melon yield. Polyethylene microtunnels were found not economical for cantaloupe production in western Mexico.

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J.A. Franco, P.J. Pérez-Saura, and A. Durán

The appearance of blossom-end rot (BER) in tomato is related to a decrease in the absorption and translocation of Ca due to excessive salinity in the soil solution. An experiment was conducted to investigate the effects of calcium nitrate (NT), EDTA-Ca (ED) and Aminoquelant-Ca (AQ)—a product containing Ca, B and protein hydrolisate—on the yield and incidence of BER when applied to the leaves of tomato (Lycopersicon esculentum Mill. `Durinta') grown in the open with a drip irrigation using saline water from a well (mean ECw 5.2 dS·m–1). The three calcium treatments and control were replicated four times, with 12 plants per replication, in a completely randomized design. Although yield per plant was higher with AQ, the difference was not statistically significant. Fewer fruit were affected by BER after treatment with ED and AQ than with NT and in the control. Leaf Ca concentration did not differ significantly between treatments. However, leaf B concentration was higher after treatment with AQ. Fruit Ca and B concentrations did not differ significantly in any treatment. The total free amino acids content in leaves was higher after AQ treatment than in the other treatments and control, although no significant difference was observed between the treatments in the fruit.

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Raúl I. Cabrera, Alma R. Solís-Pérez, and John J. Sloan

Greenhouse rose (Rosa × spp. L.) production is facing the use of poor-quality irrigation waters and regulatory pressures to recycle runoff and drainage effluents. Two experiments (were conducted to evaluate the yield and quality and ion accumulation responses of roses grafted on various rootstocks to increasing salinity stress. In Expt. 1, the scion ‘Bridal White’ grafted on ‘Manetti’, R. odorata (Andr.), ‘Natal Briar’, and ‘Dr. Huey’ were irrigated over four flowering cycles with complete nutrient solutions supplemented with NaCl at 0, 5, and 30 mm. In Expt. 2, plants of ‘Red France’ on ‘Manetti’ and ‘Natal Briar’ were irrigated over six flowering cycles with complete nutrient solutions supplemented with NaCl + CaCl2 (2:1 m ratio) at 0, 1.5, 3, 6, 12, and 24 mm. Salt concentration increases significantly and negatively affected the biomass, cut flower production, and foliage quality of the roses in both experiments, but the responses were modulated by rootstock selection. ‘Manetti’ plants in general sustained better absolute and relative biomass and flower yields, accumulated less Na+ and Cl in its tissues, and showed less toxicity symptoms with increasing salinity than the others. ‘Natal Briar’ also had similar absolute productivity responses as ‘Manetti’ but were afflicted by a significantly different mineral nutrient profile, including higher accumulations and toxicities with Na+ and Cl that led to lower foliage visual ratings. Conversely, the relative yields of plants on ‘Dr. Huey’ and R. odorata were similarly reduced by increasing salinity, but the former had lower Na+ and Cl concentrations in its tissues and better visual scores than the latter, which fared as the worst. A combined analysis of the results suggests that on a productivity basis (biomass and flower yields), greenhouse roses could withstand overall maximum electrical conductivities (i.e., osmotic effects) of applied fertigation solutions of 3.0 ± 0.5 dS·m−1. On the other hand, and considering the aesthetic responses (visual scores) of on-plant and harvested foliage (cut flower shoots), greenhouse rose tolerance to applied Na+ and Cl concentrations (ion-specific effects) could range up to 10 ± 2 mm.

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O. Pérez-Tornero, F. Ortín-Párraga, J. Egea, and L. Burgos

Apricot (Prunus armeniaca L. cv.'Helena') shoots grown on a proliferation medium containing 3% sucrose, 0.4 mg·L–1 benzyladenine (BA), and 0.04 mg·L–1 indolebutyric acid (IBA) and solidified with 0.6% agar were stored at three different temperatures in the dark for up to 24 weeks. All shoots remained viable for 24 weeks when stored at 3 °C, while at 14 °C the percentage of survival decreased quickly after 12 weeks of storage. At 7 °C, percentage of survival started to decline after 18 weeks of storage. Shoots stored at 3 °C had the highest regeneration rates and shoot lengths following transfer to standard proliferation conditions. This temperature also had a beneficial effect on shoot proliferation during the first 12 to 18 weeks of the experiment.

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Juan C. Díaz-Pérez, Albert C. Purvis, and J. Thad Paulk

Bolting causes significant economic losses in sweet onion (Allium cepa L.) production. Although temperature and photoperiod are considered to be the main factors that initiate bolting in onions, preliminary results suggested that low N fertilization rates increased bolting. The objective of our study was to determine the relationships of bolting, yield and bulb decay with N fertilization rates. The N fertilization rates applied ranged from the infraoptimal to the supraoptimal (from 102 to 302 kg·ha-1 N). Shoot and bulb N content increased with increasing N rates, but there were no differences in the respective shoot and bulb N contents among cultivars. Bolting incidence declined steadily with increasing N fertilization rates up to 197 kg·ha-1 N. Bolting incidence was among the highest in the cultivar Pegasus. The percent of decayed bulbs also increased at a steady rate with the rate of N applied. Total (14.7 t·ha-1) and marketable (0.8 t·ha-1) yields at the lowest N rate (102 kg·ha-1 N) were lower (P ≤ 0.01) than those at higher N rates. Rates of N ≥145 kg·ha-1 had no significant effect on either total (mean = 33.6 t·ha-1) or marketable (mean = 21.6 t·ha-1) yields. Losses in marketable yield were primarily a combination of bolting and bulb decay and were minimized at 162 kg·ha-1 N. Yield losses at low N rates were mostly due to bolting while yield losses at high N rates were mostly due to decay. Thus, excess applications of N fertilizer should be avoided since they have little effect on yields or bolting but they increase bulb decay.

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M.E. Pérez de Camacaro, G.J. Camacaro, P. Hadley, N.H. Battey, and J.G. Carew

The differences in growth and yield in the Junebearing strawberry (Fragaria ×ananassa Duch.) `Elsanta' and the everbearing `Bolero' and `Everest' were evaluated under field conditions. The seasonal patterns of radiation use efficiency and assimilate partitioning were also studied. Growth, development and yield showed considerable differences among cultivars. `Elsanta' showed the highest and `Bolero' and `Everest' the lowest values for almost all the vegetative parameters (leaf area, leaf dry weight, runner number). `Elsanta' produced large leaves and few crowns per plant in contrast to the everbearing cultivars which had more but smaller leaves and a larger number of crowns per plant. The production of flowers by `Elsanta' was concentrated in June with fruit production following in July. `Bolero' and `Everest' produced more than one flush of flowers during the season and fruited until October. As a result, yields of `Bolero' and `Everest' were greater than `Elsanta'. The higher yields of `Bolero' and `Everest' also reflected the greater number of crowns produced by these cultivars. The maximum intercepted and absorbed photosynthetically active radiation (PAR) occurred between July and August when the three cultivars showed the greatest increase in vegetative growth. Harvest index clearly differed among cultivars and this was related to the duration of cropping. The greatest harvest indexes were found for `Bolero' and `Everest'.

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C. Avilla, J.L. Collar, M. Duque, P. Pérez, and A. Fereres