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H.H. Ratnayaka, B. Meurer-Grimes and D. Kincaid

Manual deflowering and leaf maturity were evaluated for effect on the yields of the bioactive sennosides A and B in Tinnevelly senna (Cassia angustifolia Vahl). Deflowering increased sennoside A and B concentration (percent dry weight) in leaves by 25%, the total leaf dry mass by 63%, and the harvest index by 22%, with the result that the sennoside A and B yield (grams) per plant doubled in response to deflowering. During the same time, net photosynthesis remained consistently lower in the deflowered plants. Youngest leaves had the greatest sennoside A and B concentration. A clone raised from cuttings of one seedling had lower sennoside A:B ratio than the plants raised from the seedlings. Although crop type and possibly environmental conditions influenced the sennoside A:B ratio, deflowering and leaf maturity had no effect. The sennoside A and B concentrations in the dried leaves of deflowered plants harvested in 1.5-hour intervals appeared to increase during the course of the day. Deflowering, harvesting of young leaves, and harvesting time of day constitute promising component technologies for field investigations.

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Philip J. White, John E. Bradshaw, M. Finlay, B. Dale, Gavin Ramsay, John P. Hammond and Martin R. Broadley

horticultural and consumer practices, suggests that this phenomenon might be a consequence of the adoption of modern varieties and/or agronomic practices ( White and Broadley, 2005b ). Unfortunately, none of the studies mentioned provide sufficient data to

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C.S. Hew

Orchid cut flower industry has contributed substantially to the economy of Singapore, Thailand, Malaysia and other Asean countries. Singapore exports US$13 million dollar worth of orchid cut flower in 1990 and Thailand's export was at least 3 to 4 times higher. Germany and Japan are the major markets for tropical orchid cut flowers. Economically important orchid genera are Aranda, Dendrobium, Mokara, Oncidium and Vanda. This paper will review the agronomic practices in orchid cultivation, the current status and development of orchid industry and the research and development made towards the improvement of the orchid industry in Asean countries.

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Maureen M.M. Fitch, Paul H. Moore, Terryl C.W. Leong, Leslie Ann Y. Akashi, Aileen K.F. Yeh, Susan A. White, Amy S. Dela Cruz, Lance T. Santo, Stephen A. Ferreira and Leslie J. Poland

Papaya seedlings segregate for sex expression as females or hermaphrodites. Typically only hermaphrodite fruit are marketed in Hawaii. The agronomic practice of growing multiple seedlings that are later thinned to a single hermaphrodite tree is wasteful of seed, labor, and resources, especially when seed is costly. We compared growth of plants propagated by the clonal methods of micropropagation or rooting vegetative cuttings versus plants initiated as seedlings and transplanted. The seedlings were either single-planted hermaphrodites as identified by the polymerase chain reaction (PCR) or multiple-planted, thinned seedlings. The experiments were carried out in three different locations on two islands in Hawaii. Clonally propagated plants were significantly shorter than seedlings and bore flowers earlier and lower on the trunk at all locations. Stem diameter differences were not significant even though plant size was different at planting time. Percentage of trees in bud varied significantly in the third month after transplanting when about 90% of the rooted cuttings and large micropropagated plants had formed flower buds while only one multiple-planted seedling developed a bud. Overall, the clonally propagated plants were more vigorous and earlier bearing than were the seedling plants. There is good potential for adoption of clonal propagation when production becomes efficient enough to compete in price with the current practice of over planting and thinning.

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Griffin M. Bates, Sarah K. McNulty, Nikita D. Amstutz, Victor K. Pool and Katrina Cornish

Rubber dandelion (Taraxacum kok-saghyz, Rodin) is being developed as a temperate-zone source of rubber, but best agronomic practices must be determined before it can become a viable supplement to imported rubber produced from para rubber tree (Hevea brasiliensis, hevea) plantations located mostly in Southeast Asia. In our study, the effect of planting density and harvest time on yield was determined by transplanting 1.5-month-old greenhouse-produced plants at planting densities of 1.24, 2.47, 4.94, and 9.88 million plants/ha, randomized across four planting boxes with two densities per box (i.e., two planting areas at each density). Half of each planting area was selected randomly and hand-harvested after 6 months, and the remaining plants were hand-harvested after 1 year. Rubber yields per plant were greater after 1 year than after 6 months, but yields per unit area were similar as a result of the loss of half the plants during the severe 2013–14 Ohio winter. A maximum rubber yield of 960 kg dry rubber/ha was obtained from the 9.88 million-plants/ha planting density after 1 year, but root size was significantly decreased compared with lower densities, and appeared too small for mechanical harvest. A planting density between 2.47 and 4.94 million plants/ha may produce the optimal combination of root size and total rubber yield. Greater rubber concentrations, faster-growing plants, short-season germplasm, and in-field weed control are required before yields obtained in outdoor planting boxes can be matched or exceeded on farms, especially in a direct-seeded rubber dandelion crop.

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Fhatuwani N. Mudau, Puffy Soundy and Elsa S. du Toit

,7,8,3′,4,5′-hexamethoxyflavon-3-ol as a major flavonoid ( Mashimbye et al., 2006 ). Agronomic practices, such as plucking of leaves ( Owour et al., 2000 ) and mineral nutrition ( Owour, 1989 ; Owour et al., 1990 ; Owour and Odhiambo, 1994 ), have increased the concentration

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Fhatuwani N. Mudau, Ambani R. Mudau, Mpumelelo Nkomo and Wonder Ngezimana

reported by Mudau et al. (2007a) and can be ascribed to agronomic practices such as pruning ( Maudu et al., 2010 ). Pruning removes substantial amounts of leaves and branches, resulting in a drastic reduction of photosynthesis products ( Marasha et al

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Richard O. Nyankanga, Ocen Modesto Olanya, Hans C. Wien, Ramzy El-Bedewy, John Karinga and Peter S. Ojiambo

; Landeo and Turkensteen, 1989 ). Cultivars were grown from clean seed at the CIP's field sites at the CIP field sites at Kabete and Loreto. All standard agronomic practices were followed according to the local conditions. One to 2 weeks before harvest

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Ana Morales-Sillero, R. Jiménez, J.E. Fernández, A. Troncoso and G. Beltrán

and Kourís-Lazos, 1996 ). Factors such as cultivar, weather and soil conditions, fruit ripeness, agronomic practices, and oil extraction process modify oil chemical composition and organoleptic characteristics ( García et al., 1996 ; Salvador et al

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James D. McCurdy, J. Scott McElroy and Elizabeth A. Guertal

rates (≈500 to 700 kg perennial ryegrass seed/ha), white clover establishment rates are much lower [ Frame and Newbould (1986) recommend 3 to 5 kg white clover seed/ha]. There are several agronomic practices used to improve overseeded grass