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  • Author or Editor: Lin Wu x
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“Juvenile sod” refers to an immature sod produced in pans in a greenhouse, with only 5 to 6 weeks from seeding to harvest. Seeds were planted in peatmoss after adjusting pH to 7 and were watered with nutrient solution. Tensile strength produced in plastic pans having molded ribbed bottoms and drainage holes vs. flat-bottomed pans was compared. Covering the pans with thin plastic sheets vs. leaving them uncovered during the first 4 days of germination was examined for effect on tensile strength. Tall fescue (Festuca arundinacea Schreb), perennial ryegrass (Lolium perenne L.), and Kentucky bluegrass (Poa pratensis L.), seeded at 60 vs. 30, 60 vs. 30, and 30 vs. 15 g·m–2, respectively, were evaluated. Ribbed-bottom, covered pans, and increased seeding rates resulted in greater tensile strength, which was sufficient for marketable handling.

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The polymerase chain reaction (PCR) and RAPD fragments are potentially useful methods for identifying turfgrass cultivar breeding lines. RAPD markers were studied in 25 vegetatively propagated buffalograss lines using oligonucleotide random primers and agarose-gel electrophoresis to determine their potential for identifying cultivar breeding lines. The variation of RAPD markers was extensive. The RAPD markers produced by one random primer were sufficient to separate the 25 buffalograss lines. Cluster analysis baaed on' the RAPD markers produced by two random primers revealed that the 25 buffalograss lines generally fell into two groups: diploid and hexaploid. Three DNA extraction methods—sarcosyl lysis-chloroform extraction-isopropanol precipitation, sodium dodecyl sulfate (SDS) lysine-isopropanol precipitation, and boiling in the presence of Chelex-100 resin—and fresh or oven-dried tissues were tested for reproducibility of RAPD markers. The three DNA extraction methods, using dry or fresh plant tissues, produced highly comparable RAPD marker profiles. More than 80%1 of the RAPD markers was consistently detected in six replicate analyses. The above studies demonstrate that small quantities (5 mg) of oven-dried leaf tissue and several DNA extraction methods can be used for buffalograss fingerprint studies.

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The effect of tall fescue turf on growth, flowering, modulation, and nitrogen fixing potential of Lupinus albifrons Benth. was examined for greenhouse and field grown plants. No allelopathic effect was observed for lupine plants treated with tall fescue leachates. The nitrogen-fixing potential measured by nodule dry weight and acetylene reduction rates was not significantly affected by either tall fescue turf or low nitrogen fertilization. Both the greenhouse and field studies showed that the growth, sexual reproductive allocation, and number of inflorescences were significantly reduced when lupine plants were grown with tall fescue. The root length densities of tall fescue turf and lupine monoculture were measured. The tall fescue turf had 20 times higher root length density (20 cm cm-3 soil) than the lupine plants monoculture. This suggests that intense competition at the root zone may be a dominant factor which limits the growth of the lupine plants. The reproductive characters of the lupine plants was improved by phosphorus fertilization. Transplanting of older lupine plants into the turf substantially alleviated the tall fescue turf competitive effect.

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Abstract

A severe drought stress was imposed on a salinity-tolerant, creeping bent-grass population (‘Seaside’) under turf conditions. Salinity and osmotic stress resistance did not differ between clones collected before drought and after surviving drought stress. Survival under drought stress was greater for clones having higher heat tolerance and root/shoot ratio, but less leaf area and thinner stolons.

Open Access
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Production of tomato (Lycopersicon esculentum) during the hot-wet season in the lowland humid tropics can be increased using grafted plants and rainshelter. This technology can reduce soil-borne diseases, improve the ability of tomato plants to tolerate high temperatures and flooding due to high rainfall, and protect the crop from the impact of heavy rains. AVRDC has developed tomato lines that are resistant to virus diseases and high temperatures. This experiment was conducted to evaluate the performance of these lines in the hot-wet season, with and without rainshelter protection. Tomato lines (CHT501, TLCV15, and FMTT847) were grafted onto eggplant (Solanum melongena cv. EG203) rootstock and grown under rainshelter and open field. Nongrafted plants of three lines were also grown under two rainshelter treatments. The experimental design was a split-plot with four replications. Plants were managed using AVRDC standard practices for summer tomato production. TLCV15 and FMTT847 were highly resistant to tomato leaf curl virus (ToLCV), whereas CHT501 was greatly infected by the virus disease. All nongrafted plants died from bacterial wilt, whereas grafted plants survived the disease and outyielded nongrafted plants by 233% in the open field and 143% under rainshelters. Plants under rainshelters had a slightly lower yield than in the open field, but the difference was nonsignificant. Due to lack of frequent high rainfall during the season, the benefit of rainshelter was not detected and realized. It was concluded that TLCV15 and FMTT847 are well suited for grafted tomato production during the hot-wet season.

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Chili pepper (Capsicumannuum cv. Delicacy) was grown in single- and double-bed rainshelters and irrigated using furrow and drip irrigation to determine effect on yield and efficiency of water and nutrient application in the lowland tropics of southern Taiwan during the hot wet season. The experiment was laid out using a split-plot design with four replications. The main plots were rainshelters (single, double, open field) and the two irrigation methods (furrow and drip) were the subplots. Grafted chili seedlings were transplanted in double rows on raised beds at row spacing of 80 cm and plant spacing of 50 cm. The furrow-irrigated crop was applied with basal N-P2O5-K2O at the rate of 180–180–180 kg·ha-1 and 240–150–180 kg·ha-1 of N-P2O5-K2O as sidedressing. The drip-irrigated crop received half of the total rate applied for the furrow-irrigated crop. Significant differences (P < 0.05) in marketable yield were observed between rainshelter treatments. Highest yield (42.2 t·ha-1) was produced from the single-bed rainshelter, and crops grown under double-bed rainshelters produced the lowest marketable yield. Irrigation method did not significantly influence marketable yield, but crops grown under drip irrigation produced a higher yield than furrow-irrigated crops. Nutrient uptake by plants grown under drip irrigation was also higher (P < 0.05) than for furrow-irrigated crops. Water use efficiency was 60.7% higher in drip-irrigated plots. Results indicate that in high rainfall vegetable production areas, drip irrigation minimizes nutrient loss through leaching and maximizes efficiency of fertilizer use.

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Substantial difference of selenium tolerance was found between the tall fescue (Festuca arundinacea Schreb.) and white clover (Trifolium rapens L.) An inverse relationship between Se accumulation and Se tolerance suggests an exclusion mechanism that restricts Se uptake by the plant with greater Se tolerance. A positive relationship between the increase of protein Se concentration and growth inhibition in the plants suggests that assimilation of Se into protein is responsible for the reducing Se toxicity at the protein level. No evidence of a Se exclusion mechanism which exclude Se from incorporating into protein plays any major role of Se tolerance in this two species.

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The effects of light quality emitted by light-emitting diodes (LEDs) on the growth and morphogenesis, and concentrations of endogenous phenolic compounds of Protea cynaroides L. plantlets in vitro, were investigated. Plantlets were cultured under four light treatments: conventional fluorescent lamps (control), red LEDs (630 nm), blue LEDs (460 nm), and red + blue LEDs (1:1 photosynthetic photon flux). Four phenolic compounds extracted from the plantlets were analyzed: 3,4-dihydroxybenzoic acid, gallic acid, caffeic acid, and ferulic acid. The highest rooting percentage was observed in plantlets cultured under red LEDs (67%) compared with 7% under conventional white fluorescent light, 13% under blue LEDs, and 13% under red + blue LEDs. The highest number of roots per plantlet was also found under red LEDs, whereas a significantly lower number of roots per plantlet was obtained under the other light treatments. Furthermore, red light promoted the formation of new leaves in P. cynaroides plantlets. However, the highest leaf dry weight (53.8 mg per plantlet) was found in plantlets irradiated by the combination of red and blue LEDs. Phenolic analyses showed that the lowest concentrations of 3,4-dihydroxybenzoic acid (4.3 mg·g−1), gallic acid (7.0 mg·g−1), and ferulic acid (7.4 mg·g−1) were detected in plantlets exposed to red light, whereas those irradiated by white fluorescent light contained the highest concentration. A significant inverse correlation (r = –0.419) was established between 3,4-dihydroxybenzoic acid and rooting percentage. Strong inverse correlations were also established between 3,4-dihydroxybenzoic acid and number of roots per plantlet (r = –0.768) as well as between ferulic acid and number of roots per plantlet (r = –0.732). These results indicate that the stimulation of root formation in P. cynaroides plantlets under red LEDs is the result of the low endogenous concentrations of 3,4-dihydroxybenzoic acid and ferulic acid.

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The effects of CO2 enrichment on the in vitro growth and acclimatization of Protea cynaroides L. plantlets were investigated. Three CO2 enrichment concentrations were used: 0 (control), 1000, 5000, and 10000 μmol·mol−1. Plantlets in the control treatment were cultured on half-strength Murashige and Skoog (MS) medium supplemented with sucrose, whereas those enriched with different CO2 concentrations were grown on sucrose-free MS medium. Compared with the control, significant improvements were observed in the growth of plantlets enriched with CO2 irrespective of the concentration. Plantlets enriched with 5000 μmol·mol−1 CO2 produced the highest number of leaves and the largest leaf area. In addition, the photosynthetic ability of plantlets enriched with CO2 was enhanced, which resulted in significant increases in shoot growth and dry matter accumulation. In particular, the shoot dry weight of plantlets cultured in 5000 μmol·mol−1 CO2 and 10000 μmol·mol−1 CO2 were, respectively, 2.1 and 4.2 times higher than those without CO2 enrichment. During acclimatization, the survival percentage, rooting percentage, and leaf number of plantlets grown in elevated CO2 were, respectively, up to 4.5, 1.8, and 2.7 times higher than plantlets without CO2 enrichment. The improvements in survival percentage and ex vitro growth of these plantlets were the result of their enhanced photosynthetic ability in vitro, which resulted in the production of high-quality plantlets. Significant improvements in the overall growth of P. cynaroides plantlets were achieved through the use of photoautotrophic micropropagation with CO2 enrichment.

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Illumination during storage was proven to extend the storability of seedlings, but little attention has been given to the underlying mechanism. To determine how light conditions affect photosynthetic status in watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] plug seedlings, differences of stomatal development and relative photosynthetic characteristics of expanding new leaves when stored for 8 days at 15 °C in light at a photosynthetic photon flux (PPF) of 15 μmol·m−2·s−1 or darkness were investigated. The stomatal density (SD) increased with time to a peak and then decreased from the start of storage in light to the subsequent transplantation. Dark storage retarded the stomatal development and delayed the appearance of the peak of SD. Compared with those under dark storage, light-stored seedlings showed significantly higher SD and stomatal index (SI) in leaves accompanied by higher maximal photochemical efficiency of PSII (Fv/Fm) and quantum yield of PSII (ΦPSII). During storage in darkness, Fv/Fm and ΦPSII declined steeply with increasing storage duration but recovered gradually to reach the same level of those in light at the fourth day after transplanting. Seedlings stored in light for 8 days showed higher net photosynthesis rate (Pn), stomatal conductance (g S), intercellular CO2 concentration (Ci), and transpiration rate (Tr) than in darkness. The post-storage recovery of Pn, g S, and Tr were closely related to the SI, which ensured the fast recovery of photosynthesis during the early stage of transplanting. In agreement with the change of SD, no differences in Pn, g S, Ci, and Tr between light and dark storage were observed after 8 days of transplantation. Seedlings stored in light appeared vigorous and the shoot dry weight was significantly higher than that of dark-stored ones. Although seedlings in dark storage had a poor appearance during storage, they showed inhibited regrowth potentials during the subsequent transplanting stage. This study exhibited that light in short-term storage contributed to maintaining stomatal development as well as photosynthetic efficiency in watermelon, which could also extend to post-storage for ensuring the transplant quality of seedlings after removal from storage.

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