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  • Author or Editor: Dorota Haman x
  • HortScience x
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Frequent fertigation of soilless-grown bell pepper (Capsicum annuum L.) can increase fruit production, but development of fruit disorders may offset the increase in yield of first-quality (blemish-free) fruit in greenhouses with minimal environmental control. Fruit yield and quality were studied as affected by water volumes and nutrient concentration levels, delivered with irrigation events initiated after determined cumulative solar radiation levels, in ‘HA3378’ bell pepper from October to May in north–central Florida. Irrigation events occurred after solar radiation integral levels (SRI; ±SD) 1.7 ± 0.42, 3.7 ± 0.42, 5.7 ± 0.42, 7.7 ± 0.42, and 9.7 ± 0.42 kW·min−1·m−2, which led to mean number of daily irrigation events of 61 ± 31, 26 ± 12, 17 ± 8, 12 ± 5, and 10 ± 4 respectively. In peat mix, perlite, and pine bark media, volume per irrigation event and concentration levels of the nutrient solution were, in the first experiment, 74 mL standard (74-s), and in a second concurrent experiment, 74 mL half-standard (74-½s) or 3) 37 mL standard (37-s). In both studies, combined marketable fruit yields of first quality and second quality (minor cracking patterns and yellow spots) increased linearly with decreasing SRI (increased events per day). First-quality fruit weight with 74-s was unaffected by media and, in a quadratic response to SRI, reached 5.4 kg·m−2 at 5.7 kW·min−1·m−2. First-quality weight with 74-½s and 37-s did not differ. Weight was unaffected by SRI in peat mix and perlite, and a quadratic response was recorded in pine bark, with yields of ≤3.6 kg·m−2. Fruit cracking incidence decreased with increased SRI, and was generally greater in pine bark. Incidence of yellow spots doubled with 74-½s compared with 37-s, and decreased linearly with increased SRI; the disorder was minor with 74-s. Compared with 37-s, 74-½s decreased fruit with blossom-end rot by 14%, increased marketable fruit weight by 10% in media with the lowest water-holding capacity (perlite, pine bark), and increased nutrient use efficiency. With any media used, the SRI set point of 5.7 kW·min−1·m−2 (daily mean of 17 irrigation events) and 74 mL, at standard nutrient concentration levels, appeared to produce greater blemish-free fruit yield than delivering 37 mL/event or half-concentrated 74 mL/event within the range of SRI means of 1.7 to 9.7 kW·min−1·m−2 (61–10 irrigation events/day). Disorder-tolerant pepper cultivars, better temperature control, and August plantings are additional suggestions for irrigation management to increase first-quality fruit yield.

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Two colors (white and black) of a recently introduced irrigation-plant production system [multi-pot box system (MPBS)] for container-grown nurseries were researched and results were compared with those obtained from the sprinkler-irrigated conventional (control) system (CS). Experiments were carried out in summer and fall of 2001 in Gainesville, Fla. Plant growth [growth index (GI), growth rate (GR), and dry matter] and stress parameters [stomatal resistance (rs), crop water stress index (CWSI), plant water potential (PWP), and substrate temperature (ST)] were measured and analyzed for Viburnum odoratissimum (Ker-gawl). In both seasons, plants grown in the white MPBS had significantly higher GI and GR as compared to the plants in the black MPBS and CS. In summer, plants in the white MPBS reached marketable size about 17 days and 86 days earlier than those in the black MPBS and CS, respectively. In fall, they reached marketable size about 25 and 115 days earlier than those plants in the black MPBS and CS, respectively. Plants in the white and black MPBSs showed exponential growth rate in summer with plants in the white MPBS having significantly higher growth rate (greater slope) than the other two treatments. In both seasons, plants in the white MPBS produced the highest amount of dry matter. In general, plants in the white MPBS had lower rs values to vapor transport compared to the other two treatments, and the black MPBS treatment had lower rs values than the CS in both seasons. The CWSI values of the plants in both white and black MPBSs were significantly lower than the CS. In both seasons, ST in the black MPBS and CS exceeded the critical value of 40 °C several times. The ST of >40 °C is often reported to significantly reduce the plant growth and cause root death and/or injury for container-grown plants. Overall, the white MPBS provided a better environment for root development and plant growth under these experimental conditions. Results strongly suggest that there is a potential opportunity of using MPBS for irrigation and production of nursery plants. These important findings suggest that, in practice, producing nursery plants in a shorter period of time by using white MPBS will result in significant savings of energy, water, chemicals, and other inputs and thereby reducing the costs and increasing profits.

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