A New Efficient Ordering Scheme for Sphere Detection

The decoding order has a deep impact in the complexity of sphere detection. A new ordering scheme for sphere detection is presented in this paper, which is based on SIC (serial interference canceling) and the gradient defined by the accumulated probability of the absolute difference between symbol element and the zero-forcing solution. The simulation results show that the proposed ordering scheme can achieve a significant complexity reduction, especially for high numbers of antennas and large constellation sizes in the low SNR region. Compared with sphere detection complexity under BSQR (balanced sorted QR) decomposition and GB (gradient-based) orderings atSNR=5 dB, the average number of visited nodes under our proposed ordering is reduced by almost 30% and 33% in4×416QAM system and by almost 30% and 50% reduction in6×616QAM system, respectively. For4×464QAM system, almost 75% and 80% reduction atSNR=0 dBand more than 40% and 50% reduction atSNR=5 dBcan be achieved, respectively.

347 Rooting of Softwood Cuttings from Dormant Woody Stems Forced in a Forcing Solution Containing Silver Thiosulfate and Gibberellic Acid

Research was conducted in Feb. 1999 to study the effects of including silver thiosulfate (STS), gibberellic acid (GA3), or both in the forcing solution on rooting of softwood cuttings produced by forced dormant woody plant species. The cuttings were dipped for 10 s in 2000 ppm indole-3-acetic acid (IAA) or 2000 ppm indolebutyric acid (IBA). High percentages of rooting were observed in the two woody plant species examined. Root number and length of the new growth of Cornus alba and Euonymus alatus forced in a forcing solution containing the basic forcing solution treatment (8-HQC at 200 mg·L-1 + 2% sucrose), the STS treatment, or the combination treatment of STS + GA3 were not significantly different. However, treating the dormant stems of the two woody plant species examined in a forcing solution containing only GA3 led to fewer and shorter roots when compared to all other treatments. Applying either IAA or IBA to the new softwood growth led to similar root length and number for both species. This forcing solution approach provides an attractive alternative for propagating woody plants during winter months.

107 Silver Thiosulfate (STS) Alone and in Combination with Gibberellic Acid (GA3) in the Forcing Solution Influences Budbreak and Shoot Elongation of Dormant Woody Plant Species

Research was conducted to further modify the forcing solution system in order to expedite the propagation of woody plants, such as Spiraea canescens, Lonicera maakii, and Cornus alba. Time of immersion in solutions containing 5 mM silver thiosulfate (STS) was compared with the basic forcing solution reported by Yang and Read (1989), a solution containing 200 mg 8-hydroxyquinoline citrate per liter and 2% sucrose. Other treatments employed were gibberellic acid (GA3) 50 mg per liter for 24 h and a combination of STS and GA3 for the same amount of time. Increasing the time in STS solution up to 24 h led to higher percent budbreak and shorter time to budbreak for all the three species examined. The combination of STS and GA3 was the most effective treatment overall in reducing time of budbreak and increasing percent of budbreak. All STS treatments studied showed similar responses in shoot elongation. However, treatments with GA3 alone, and in combination with STS showed more than a doubling in shoot length compared to all STS treatments studied and the control. Implications based on SEM observations will be presented.

Use of Forcing Solution Techniques to Improve Chestnut Micropropagation

Chestnut (Castanea spp.) is considered difficult to micropropagate. The timing for harvesting explant materials from forced stems is critical, although many factors need to be considered for successful micropropagation. Previous research with spirea and five-leaf aralia demonstrated that forcing solution techniques extended the availability of high-quality explant material, thus expediting micropropagation. However, preliminary research illustrated that chestnut is very difficult to force and the new forced softwood growth is very short-lived, which made micropropagation difficult. It was found that, at about 7 days from budbreak, the forced chestnut softwood growth (about 2 cm long) served as the best explant material. If longer than this timing window, the new growth would die. If shorter, the explants had a high contamination rate, exudation of purported phenolic compounds, and explants would not regenerate. Shoot proliferation and callus regeneration were achieved by culturing good-quality explants on Woody Plant Medium supplemented with 0.1 mg BA/liter. The new shoots grew vigorously in vitro with apparent normal morphology.

569 PB 012 A MODIFIED FORCING SOLUTION SYSTEM PROMOTES PROPAGATION OF WOODY SPECIES

A forcing solution containing 200 mg 8-hydroxyquinoline citrate per liter and 2% sucrose has enhanced availability of cutting materials by forcing dormant woody stems in the off-season. Anxins, such as IBA, included in the forcing solution promoted subsequent rooting by increasing root number per cutting and root length for privet. Inclusion of IBA in the forcing solution following the initial use of GA3 in the forcing solution counteracted the undesirable effects of GA3 on rooting and stimulated rooting after taking advantage of the favorable effects of GA3 on bud break and shoot elongation. However, the ability of IBA to counteract the negative effects of GA3 on rooting was dependent on the length of GA3 treatment. The modification of forcing solution system by sequentially including GA3 and then replacing GA3 with IBA expedited propagation of privet. Production of candidate cuttings or explants was stimulated by including GA3 in the forcing solution, and rooting of the cuttings was promoted by subsequent auxin or cytokinin inclusions in the forcing solution to replace GA3 This modified forcing solution system also proved to be a successful and efficient model for propagation of other difficult to propagate woody species.