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  • Author or Editor: Jorge F.S. Ferreira x
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Hazel Y. Wetzstein, Jules Janick and Jorge F.S. Ferreira

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Jorge F.S. Ferreira, James E. Simon and Jules Janick

Artemisinin (qinghaosu), an endoperoxide sesquiterpene lactone with antimalarial activity and little human toxicity, is produced in A. annua L., a short-day plant with the critical photoperiod of 13.5 h. Artemisinin peaks at full flowering when it is 11 times higher in inflorescences than in leaves. Supplementation of MS medium with BA, kinetin, CCC, or daminozide decreased content in shoot cultures as compared to the control, with the exception of CCC at 6.3 μM. Artemisinin content (percent dry weight) in this experiment did not correlate with shoot number (r = –0.198) but was highly correlated (r = 0.775**) with root number, indicating that although roots do not produce artemisinin, they may be involved in its synthesis. Maximum artemisinin was produced in hormone-free medium. Friable calli were obtained with a combination of BA (4.4 μM) and 2,4-D (4.5 μM), but artemisinin was absent from calli, cells, and cell culture media. Biseriate glandular trichomes are present in leaves and flowers from the earliest developmental stages. Artemisinin was extracted by a 1-min dip in organic solvents from flowers and leaves, indicating that the biseriate glandular trichomes of A. annua are the probable site of accumulation or sequestration of artemisinin.

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Jaime Barros da Silva Filho, Paulo Cezar Rezende Fontes, Paulo Roberto Cecon, Jorge F.S. Ferreira, Milton E. McGiffen Jr. and Jonathan F. Montgomery

Potato seed production by conventional methods represents a sizeable investment that, when passed on to farmers, can decrease their profit margins. Potato minitubers produced by aeroponic systems are space- and cost-efficient, and they also provide healthy propagules to be used by farmers. We evaluated the effects of different misting nozzle types, with and without an antidrip feature, and spray direction on potato minituber yield using the Federal University of Viçosa (UFV) Aeroponic System. Potato plants (cv. Agata) propagated from sprouts were grown in a covered, high-density 100-L polyethylene bucket. The experiment was set up in a randomized complete block design with four replicates and eight treatments combining misting nozzle types (Fogger, MA-30, and CoolNet) with and without antidrip and comparing upward with downward spray directions. Plants were evaluated weekly from 33 to 68 days after transplant (DAT). The parameters used to evaluate treatments were number and mass of minitubers as a function of harvest times, dry mass of roots, stems, leaves, and total biomass. The number and fresh weight of minitubers, as well as root dry weight, stems, leaves, and total biomass were affected by misting nozzle types and spray direction. Treatments also affected biomass partitioning of roots, stem biomass, and the shoot:root ratio. There was also an effect of harvest time on the number and fresh weight of minitubers for various combinations of misting nozzle type and spray direction, except for minituber number with the CoolNet misting nozzle without antidrip and downward spray direction. On the basis of the assessed parameters, the best minituber production system was achieved with the Fogger spray combined with no antidrip, a rate of 12 L·h−1, and with the downward spray direction. The UFV Aeroponic System produced an average of 491 minitubers per plant. This system is simple to implement and may lead to a more affordable upscaling of potato seed minituber production.