scholarly journals Survival of Young Cold-hardened `Hamlin' Orange Trees at – 6.7C

HortScience ◽  
1990 ◽  
Vol 25 (1) ◽  
pp. 98-99 ◽  
Author(s):  
George Yelenosky
Keyword(s):  
Oxygen Uptake ◽  
Citrus Sinensis ◽  
Photon Flux ◽  
Controlled Environment ◽  
Photosynthetic Photon Flux ◽  
Test Room ◽  
Rough Lemon ◽  
Tree Survival ◽  
Freeze Test ◽  
Orange Trees

Potted greenhouse-grown, l-year-old `Hamlin' orange [Citrus sinensis (L.) Osbeck] trees on 1.5-year-old rough lemon (C. jambhiri Lush.) rootstock were temperature-conditioned for 6 consecutive weeks in a controlled-environment room to test cold-hardening ability. Holding at 15.6 ± 0.6C during 12-hr days [425 μmol·s-1·m-2 photosynthetic photon flux (PPF) at top of trees] and 4.4C during nights resulted in 100% tree survival and no leaf loss “after 4 hr of – 6.7C in a dark freeze test room. Unhardened greenhouse trees were killed to rootstock. Solute efflux (dS·m-1) from unhardened frozen leaves was > 20-fold that from frozen leaves on hardened trees and nonfrozen leaves on unhardened trees. Oxygen uptake was not significantly impaired in frozen hardened leaves. No 02 uptake was evident for frozen unhardened leaves.

scholarly journals Pre-Harvest UV-B Radiation and Photosynthetic Photon Flux Density Interactively Affect Plant Photosynthesis, Growth, and Secondary Metabolites Accumulation in Basil (Ocimum Basilicum) Plants

Agronomy ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 434 ◽  
Author(s):  
Haijie Dou ◽  
Genhua Niu ◽  
Mengmeng Gu
Keyword(s):  
Phenolic Compounds ◽  
Flux Density ◽  
Photosynthetic Photon Flux Density ◽  
Ocimum Basilicum ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Yield Reduction ◽  
Controlled Environment ◽  
Photosynthetic Photon Flux ◽  
Plant Yield

Phenolic compounds in basil (Ocimum basilicum) plants grown under a controlled environment are reduced due to the absence of ultraviolet (UV) radiation and low photosynthetic photon flux density (PPFD). To characterize the optimal UV-B radiation dose and PPFD for enhancing the synthesis of phenolic compounds in basil plants without yield reduction, green and purple basil plants grown at two PPFDs, 160 and 224 μmol·m−2·s−1, were treated with five UV-B radiation doses including control, 1 h·d−1 for 2 days, 2 h·d−1 for 2 days, 1 h·d−1 for 5 days, and 2 h·d−1 for 5 days. Supplemental UV-B radiation suppressed plant growth and resulted in reduced plant yield, while high PPFD increased plant yield. Shoot fresh weight in green and purple basil plants was 12%–51% and 6%–44% lower, respectively, after UV-B treatments compared to control. Concentrations of anthocyanin, phenolics, and flavonoids in green basil leaves increased under all UV-B treatments by 9%–18%, 28%–126%, and 80%–169%, respectively, and the increase was greater under low PPFD compared to high PPFD. In purple basil plants, concentrations of phenolics and flavonoids increased after 2 h·d−1 UV-B treatments. Among all treatments, 1 h·d−1 for 2 days UV-B radiation under PPFD of 224 μmol·m−2·s−1 was the optimal condition for green basil production under a controlled environment.

scholarly journals Influence of Cultivar and Seasonal Growing Environment on Growth and Postharvest Characteristics of Single-shoot Pot Rose Plants

HortScience ◽  
2004 ◽  
Vol 39 (1) ◽  
pp. 138-141
Author(s):  
José Antonio Saraiva Grossi ◽  
H. Brent Pemberton ◽  
Harvey J. Lang
Keyword(s):  
Photon Flux ◽  
Controlled Environment ◽  
Flower Longevity ◽  
Photosynthetic Photon Flux ◽  
Fluorescent Lamps ◽  
Flower Diameter ◽  
Single Shoot ◽  
Growing Environment ◽  
Growth Chambers ◽  
Growing Conditions

Rooted liners of pot rose (Rosa L.) cultivars Meiferjac, Meigagul, Meighivon, Meishulo, Ruijef, Ruidodo, and Ruirosora were used to study the influence of cultivar and seasonal growing environment on growth and postharvest performance. Single-shoot plants were grown in controlled environment chambers simulating summer (30 °C day/21 °C night cycle with a 14-hour photoperiod) and winter (21 °C day/16 °C night cycle with a 10-hour photoperiod) greenhouse growing conditions. At flower developmental stage 2 (showing color, calyx reflexing, no petals reflexed), the plants were placed in a continuously lighted simulated interior evaluation room at 21 ± 1 °C under 15 μmol·m-2·s-1 photosynthetic photon flux from cool-white fluorescent lamps for postharvest evaluations. Plants had quicker flowering, smaller flower diameter, more compact growth, and smaller leaf area when grown under the summer environment compared to the winter environment. Most cultivars exhibited greater flower longevity on summer-grown plants when compared to winter-grown ones. `Ruirosora' did not exhibit this difference due to exceptional longevity on winter-grown plants. Also, the use of single-shoot plants was shown to be a potentially useful way to increase replication in small growing environments such as growth chambers.

scholarly journals Uptake Patterns of 11 Elements of Orange Trees in Solution Culture

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 486B-486
Author(s):  
H.K. Wutscher
Keyword(s):  
Nutrient Solution ◽  
Citrus Sinensis ◽  
Soil Extract ◽  
Solution Culture ◽  
Field Soil ◽  
Rough Lemon ◽  
Valencia Orange ◽  
Orange Trees ◽  
Solution Change ◽  
Complete Nutrient Solution

Three trees each of `Valencia' orange (Citrus sinensis L. Osbeck) on rough lemon (C. limon L. Burm. f.) rootstocks that had been grown in solution culture since July 1989 were grown in two solutions from Oct. 1995 to Sept.1996. Solution 1 was a soil extract made by boiling field soil (1:2 soil:water) for 20 min and filtering. Solution 2 was a complete nutrient solution. The solutions were analyzed every 7 days and changed every 28 days. At each solution change, the newly prepared solutions were analyzed for 11 elements and their depletion was determined by weekly analysis. Nearly all the N, K, and Mn in Solution 1 was absorbed in the first 7 days after each solution change; in Solution 2, N and Mn were also absorbed in 7 days, but K absorption was variable; single trees sometimes needed 4 weeks to absorb all the potassium. Calcium and Mg were never completely absorbed and in contrast to Mn, traces of Fe, Zn, and Cu remained in both solutions after 4 weeks.

scholarly journals Apparent Nucleation and Freezing in Various Parts of Young Citrus Trees during Controlled Freezes

HortScience ◽  
1991 ◽  
Vol 26 (5) ◽  
pp. 576-579 ◽  
Author(s):  
George Yelenosky
Keyword(s):  
Tissue Damage ◽  
Citrus Sinensis ◽  
Sweet Orange ◽  
Rapid Progression ◽  
Rough Lemon ◽  
Initial Freezing ◽  
Orange Trees ◽  
Soil Level ◽  
Citrus Trees

One- to 4-year-old sweet orange trees, Citrus sinensis (L.) Osbeck cv. Valencia on rough lemon (C. jambhiri Lush.) rootstock, were used in a series of tests on the depth and stability of supercooling in various parts of greenhouse-grown trees held in pots during controlled freezes. Thermocouples were attached to flowers, fruit, leaves, and wood. Supercooling levels were inconsistent, ranging from – 3C to – 7C. Nucleation was spontaneous and well defined by sharp exotherms. Rapid progression of crystallization (≈ 60 cm·min–1) indicated no major obstacles to ice propagation throughout the tree above soil level. The site of initial freezing was variable, with a tendency for trees to freeze from the base of the stem toward the top. The location of tissue damage did not necessarily correspond to the location of initial freeze event. Freezing in the wood often preceded freezing of flowers.

scholarly journals CAN PLANTS DETECT SMALL DIFFERENCES IN IRRADIANCE OBTAINED BY VARYING THE REFLECTANCE PROPERTIES OF THE GROWTH CHAMBER WALLS?

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 656b-656
Author(s):  
Donald T. Krizek ◽  
Roman M. Mirecki ◽  
Alton L. Fleming
Keyword(s):  
Shoot Elongation ◽  
Growth Chamber ◽  
Photon Flux ◽  
Controlled Environment ◽  
Wall Surface ◽  
Photosynthetic Photon Flux ◽  
Fluorescent Lamps ◽  
Environment Study ◽  
Growth Chambers

A controlled-environment study was conducted in separate growth chambers with the wall surface covered either with white enamel paint (WEP) or polished aluminum (PA). `Williams' soybean were grown under 1500 mA cool white fluorescent lamps and internodes measured at 7, 14, and 21 days. Photosynthetic photon flux (PPF) levels in the center of each chamber were set at 320 μmol m-2 s-1 with a quantum sensor. Means ± SD for PPF levels in the WEP and PA chambers were 286 ± 28 and 307 ± 11 μmol m-2 s-1, respectively. This increase in mean PPF and decrease in variance of PPF in the PA chamber was reflected in: a) a decrease in hypocotyl, first internode, and total shoot elongation: and b) an increase in enlargement of the primary and the first trifoliolate leaves. These findings demonstrate that plants can detect small differences in irradiance within a growth chamber and suggest the advantages of using a highly polished wall surface to improve uniformity of irradiance and reduce variability in growth.

Potential Effects of Global Atmospheric CO2Enrichment on the Growth and Competitiveness of C3and C4Weed and Crop Plants

Weed Science ◽  
1980 ◽  
Vol 28 (1) ◽  
pp. 71-75 ◽  
Author(s):  
D. T. Patterson ◽  
E. P. Flint
Keyword(s):  
Dry Matter ◽  
Dry Matter Production ◽  
Photon Flux ◽  
Controlled Environment ◽  
Photosynthetic Pathway ◽  
Photosynthetic Photon Flux ◽  
Analysis Techniques ◽  
Unit Leaf ◽  
Matter Production ◽  
Net Assimilation

Mathematical growth analysis techniques were used to evaluate the effects of CO2concentrations of 350, 600, and 1000 ppm (v/v) on growth and biomass partitioning in corn(Zea maysL. ‘Dekalb XL 395’), itchgrass (Rottboellia exaltataL. f.), soybean [Glycine max(L.) Merr. ‘Tracy’], and velvetleaf (Abutilon theophrastiMedic). Controlled environment chambers with day/night temperatures of 28/22 C and photosynthetic photon flux densities (PPFD) of 650 μE (microeinsteins) m-2s-1were used. Dry matter production in the two C3species (soybean and velvetleaf) was increased significantly by raising the CO2concentration above 350 ppm. In corn (a C4species), dry matter production was least at 1000 ppm CO2and did not differ between the 350 and 600 ppm treatments. In itchgrass (also C4), dry matter production was greatest at 600 ppm CO2and did not differ between the 350 and 1000 ppm treatments. Increasing the CO2concentration increased the rate of dry matter production per unit leaf area (net assimilation rate or NAR) in soybean and velvetleaf but either decreased or did not alter NAR in corn and itchgrass. At 45 days after planting, the weed/crop ratios for total dry matter production for velvetleaf/corn and itchgrass/corn were significantly greater at both 600 and 1000 ppm than at 350 ppm CO2. The weed/crop ratio for itchgrass/soybean was less at 1000 ppm than at 350 or 600 ppm CO2. Compared to the value at 350 ppm, the weed/crop ratio for velvetleaf/soybean was greater at 600 ppm and less at 1000 ppm CO2. We conclude that atmospheric CO2enrichment probably will make weeds with the C3photosynthetic pathway more competitive with crops having the C4pathway. Weeds with the C4pathway may become less competitive with crops having the C3pathway.

scholarly journals Tolerance of Watermelon Seedlings to Low-temperature Chilling Injury

HortScience ◽  
2014 ◽  
Vol 49 (3) ◽  
pp. 240-243 ◽  
Author(s):  
Elzbieta U. Kozik ◽  
Todd C. Wehner
Keyword(s):  
Low Temperatures ◽  
Citrullus Lanatus ◽  
Chilling Injury ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Controlled Environment ◽  
Optimal Conditions ◽  
Photosynthetic Photon Flux ◽  
Chilling Temperatures

Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] is one of the Cucurbitaceae species and subtropical crops that exhibit chilling injury (CI) when exposed to low temperatures. Watermelon seedlings were tested for chilling tolerance using methods modified from cucumber. Three experiments were conducted using different combinations of chilling durations of 6, 12, 24, or 36 hours and chilling temperatures of 2 or 4 °C. Watermelon seedlings were more resistant to low temperatures than cucumber seedlings, so it was necessary to use long chilling durations to induce significant foliar damage. A diverse set of 16 watermelon cultigens was tested: Allsweet, Black Diamond, Chubby Gray, Charlee, Charleston Gray, Dixielee, Golden, Golden Honey, New Winter, NH Midget, Sugar Baby, Sugarlee, Sunshade, PI 189225, PI 244018, and PI 595203. Experiments were conducted in a controlled environment with a light intensity of 500 mmol·m−2·s−1 photosynthetic photon flux density (PPFD). Optimal conditions for chilling treatment were 36 hours at 4 °C or 24 hours at 2 °C. The most resistant cultigen was PI 244018, and the most susceptible cultigens were NH Midget and Golden.

scholarly journals Effects of Photosynthetic Photon Flux, Photoperiod, and CO2 Enrichment on the Growth and Morphogenesis of Lettuce Plug Transplants

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 542E-543
Author(s):  
Yoshiaki Kitaya ◽  
Genhua Niu ◽  
Maki Ohashi ◽  
Toyoki Kozai
Keyword(s):  
Co2 Enrichment ◽  
Dry Weight ◽  
High Light Intensity ◽  
Leaf Length ◽  
Plant Production ◽  
Photon Flux ◽  
Controlled Environment ◽  
Photosynthetic Photon Flux ◽  
Artificial Lighting ◽  
Fluorescent Lamps

Artificial lighting is widely used in controlled environment plant production to enhance plant growth and quality. However, high light intensity with artificial lighting is costly, and often causes increase of leaf temperature and, thus, leaf burn. We investigated the effects of photosynthetic photon flux (PPF) and photoperiod on the growth and morphogenesis of lettuce plug transplants under ambient and enriched CO2 levels. Three days after seeding, the plants were cultured under four PPF levels (100, 150, 200, and 300 μmol·m–2·s–1), two photoperiods (16 and 24 hr), and two CO2 levels (400 and 800 μmol·mol–1) for 18 days in growth chambers. Light source was fluorescent lamps. The air temperature around the plants was kept at 20°C. The results showed that dry weight of the plants increased linearly as PPF and daily integrated PPF (product of PPF and photoperiod) increased under both CO2 levels. At the same daily integrated PPF, higher CO2 level and longer photoperiod led to higher dry weight of the plants. CO2 enrichment increased significantly dry weight of the plants. The ratio of T/R and specific leaf area of the plants decreased quadratically as daily integrated PPF increased under both CO2 levels. The ratio of leaf length to leaf width of the plants decreased quadratically as PPF increased under the two photoperiods and CO2 levels.

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