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Joo Hyun Lee*, Yong-Beom Lee, and Kang Pal Kwon

This study was conducted to determine the growth and flower quality of single-node cutting rose `Versillia' under two different irrigation control methods (time clock and integrated solar radiation). The frequency of irrigation was controlled by time clock and integrated solar radiation of 1.25 and 2.09 and 3.35 MJ·m-2 in aeroponics. Photosynthesis was the highest in the integrated solar radiation of 2.09 MJ·m-2 and 1.25 MJ·m-2 the lowest in the integrated solar radiation of 3.35 MJ·m-2. The growth of single-node cutting rose `Versillia' at 1.25 MJ·m-2 and 2.09 MJ·m-2 was better than 3.35 MJ·m-2 for stem length and fresh weight. Root activities of single-node cutting rose were significantly higher at 2.09 MJ·m-2 and 1.25 MJ·m-2 than those at 3.35 MJ·m-2. The irrigation control method using integrated solar radiation of 1.25-2.09 MJ·m-2 showed a improvement of plant growth and flower quality.

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Joo Hyun Lee, Yong-Beom Lee, and Kyu Sook Lee

Wasabi japonica plantlets were acclimatized in a hydroponic system to determine effective procedures. The plantlets were cultured on solid Murashige-Skoog medium with 3% sucrose. Shoots that formed roots were transplanted into hydroponic systems: 1) acclimatization in ebb-and-flow (EBB) for subirrigation (medium: granulated rockwool and coir); and 2) acclimatization in deep flow technique (DFT). The plantlets were acclimatized for 5 weeks under two irradiance treatments, 50 and 300 mmol·m-2·s-1. Photosynthetic capacity in high PPF was higher than that in low PPF during acclimatization. Electron transport rate from PS II (ETR) and biomass production increased significantly with increased light availability. The fresh weight, dry weight, and leaf area of plantlets in high PPF were higher than those in low PPF. In particular, the dry weight and ETR of the plantlets grown in high PPF increased more than twice as much as those in low PPF. At 50 mmol·m-2·s-1 PPF, growth indexes, such as number of leaves, leaf length, leaf width, leaf area, fresh weight, and dry weight, were higher in EBB (granulated rockwool) > EBB (coir culture) > DFT. At 300 mmol·m-2·s-1 PPF, those indexes were higher in DFT > EBB (granulated rockwool) > EBB (coir). The Wasabi japonica plantlets acclimatized in a hydroponic system also had a superior performance when they were transferred to the field.

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Jude W. Grosser, Hyun Joo An, Milica Calovic, Dong H. Lee, Chunxian Chen, Monica Vasconcellos, and Frederick G. Gmitter Jr

Somatic hybridization through protoplast fusion has proven to be a valuable technique in citrus for producing unique allotetraploid breeding parents that combine elite diploid selections. Many citrus somatic hybrids are now flowering and being used in interploid crosses to generate triploid hybrids that produce seedless fruit, a primary objective of citrus breeding programs. Most of the early somatic hybrids produced for mandarin improvement combined sweet oranges with mandarins, because the performance of sweet oranges in tissue/protoplast culture generally exceeds that of most mandarin selections. However, a high percentage of triploid progeny from interploid crosses using sweet orange + mandarin somatic hybrids as the tetraploid parent produce fruit that are difficult to peel. We report nine new allotetraploid somatic hybrids and five new autotetraploids from somatic fusion experiments involving easy-peel mandarin parents. These tetraploids can be used in interploid crosses to increase the percentage of seedless triploid progeny producing easy-to-peel fruit. Ploidy level of the new tetraploids was determined by flow cytometry and their genetic origin by expressed sequence tag–simple sequence repeat marker analysis.