中亚热带米槠阔叶林单木质量分类评价

于2022年在福建省中部尤溪县国有林场,以中亚热带米槠(Castanopsis carlesii)群落作为研究对象,通过构建胸径、树高、冠幅、活冠层比重、树冠枯梢比重、树冠密度等11项指标体系,运用模糊综合评价进行单木质量分类,分类结果选择线性判别分析和K近邻算法建立预测模型,10折交叉验证并做精度评估,建立一种快速评价单木质量的研究方法。结果表明:单木质量分类结果中,4种评价等级差、中、良、优的林木占比分别为22.20%、30.19%、30.45%、17.16%,总体质量等级以良和中为主。交叉验证分析线性判别预测模型误判率、准确率分别为14.18%、85.82%,K近邻算法误判率、准确率分别为11.84%、88.16%。混淆矩阵分析线性判别误差主要出现在中和优之间,K近邻算法误差主要出现在中和良之间。综合结果表明,K近邻算法的准确率、平均精确率和召回率均优于线性判别分析,所建立的单木质量预测模型,可以在保证一定预测精度的前提下,快速评判研究区内米槠阔叶林单木质量。

Importance of the Role of Gibberellic Acid and Potassium Nitrate in Seed Germination Habanero

The habanero chili （Capsicum chinense Jacq.） is a species of great demand in the domestic and international markets. One problem in the cultivation is low percentage of seed germination. There is little information on the use of promoters and imbibition time to increase this parameter, without compromising the quality of seedlings. In this context, authors assessed the independent effect of GAs （gibberellic acid） and KNOs at concentrations of 0, 100, 200, 300, 400 and 500 mg·L1. Seeds without preconditioning were the witness. The experimental unit was a Petri dish with 50 seeds on filter paper placed equidistant. There were three replicates per treatment and the experimental design was randomized complete block. Imbibition time was 24 h. The experimental units were kept in an incubator at 22 ± 2 ℃. From the time of planting and for periods of 24 h for 14 d, experimental units were reviewed to determine the time at the beginning of germination and the total cumulative percentage. The authors also determined the number of normal and abnormal seedlings, the length of hypocotyl and radicle, weight of fresh and dry matter of seedlings. On the fifth day after sowing in vitro, concentrations of 500 mg·L^-1 of GAs, 300 and 400 mg·L^-1 KNO3, increased 208% the percentage of seed germination of habanero chile. On day 14 after sowing in vitro concentrations of 500 mg·L^-1 GA3, 300 and 400 mg·L^-1 KNO3, increased 23% normal seedlings and 40% dry matter thereof, with respect to seeds obtained without preconditioning. Unconditioned seeds before sowing produced 125% more seedlings.

Pure and mixed plantations of Persian walnut (Juglans regia L.) for high quality timber production in Chile, South America

Aims Persian walnut(Juglans regia L.),an interesting forest species for the veneering industry,requires adequate management to produce valuable high-quality logs.Since species associations and management level can improve stand productivity,the novelty of this work was to assess Persian walnut performance in different planting mixtures and in pure plantations conditioned to management intensity.Methods Growth,straightness and survival measurements were taken annually for 7 years after planting pure and mixed plantations under two contrasting management scenarios.Diseases were recorded at Age 7 in all plantations.Under each management intensity,besides the monoculture,three mixtures were tested:a mixture of only main forest species,main forest species plus one arboreal companion species,Black alder(Alnus glutinosa L.)and main species plus the shrub Russian olive(Elaeagnus angustifolia L.)as nurse species.A test of interaction between plantation type and management scenario was conducted using repeated growth data.Important Findings The interaction was significant,indicating the presence of different mechanisms underlying plantation effects under high and low management level.Compared with pure plantations,Persian walnut associated with the nurse shrub exhibited 78%higher height and 53%higher diameter growth in plantations under low management.Health benefits(lower presence of walnut blight than in the monoculture)and better straightness were also found in the association including the shrub when the management intensity was not high.These beneficial effects in the presence of Russian olive were not present under high management intensity(irrigation,fertilization,tutoring and frequent pruning).Site-specific designs for Persian walnut plantations would depend on the foreseen management intensity.