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31.
Open pollinated progenies from 15 clones of Japanese black pine (Pinus thunbergii), that had been selected for their tolerance to pine wilt disease, were tested by artificial inoculation with pine wood nematode
for six years at a nursery of Kyushu Regional Breeding Office. Family variations in the respective year were all significant.
An analysis of variance across the six years’ tests confirmed highly significant effect of year and of families; however,
the year by family interaction was significant also. Phenotypic and genetic variances estimated from each year’s result were
fitted to a quadratic regression using their mean survival ratio as an independent variable. The variances were greatest at
around 0.5 of the mean survival ratio. Estimated heritability showed a similar trend of change, whereas the peak of the expected
amount of improvement shifted toward the lower survival range: around 0.4, where a greater selection differential was anticipated.
It was concluded that a useful amount of genetic improvement that may be reduced by 30% due to the interaction, would be expected
by prescreening seedlings where the mean survival ratio after inoculation was around 0.25 to 0.6. 相似文献
32.
We studied the influence of temperature and near- and sub- optimal mineral nutrition of black spruce seedlings (Picea mariana [Mill.] B.S.P.) during their second growing period on bud set, bud development, growth, mineral content and cold tolerance. Bud break and growth after bud break were also studied. Seedlings were grown for 106 d in growth chambers under three temperature regimes in combination with three concentrations of a fertilizer. They were then cold hardened for 56 d and dehardened for 66 d.Under these near- and sub-optimal N levels, bud formation occurred during the growing season. Bud formation was accelerated with decreasing fertilization, but was not affected by temperature treatments. Needles from seedlings with 0.64% N (dry mass basis) before hardening did not harden. Those with 0.87% N showed a lesser degree of hardiness than those with 1.28% N. Stem diameter increased at the beginning of the hardening period. During this acclimation period, shoot dry mass decreased with time at a constant rate and at the same rate over time for all treatments whereas root dry mass was more variable. Total number of needle primordia was low and no difference was observed among growing conditions. Bud break was similar in all treatments. Following bud break, shoot height and stem diameter increases were small but their magnitude varied with the nutritional regimes applied during the previous growing period. During hardening, nitrogen concentration of shoot tissues first increased and then decreased; phosphorus concentration first increased and then remained stable; potassium concentration remained stable. Concentration of these three elements generally decreased in the roots during this hardening. 相似文献
33.
34.
红茶色素(茶红素、茶黄素)是红茶生产过程中茶多酚类物质经过多种氧化而形成的,是红茶品质形成的关键物质;作为纯天然的有机色素,红茶色素具有清除自由基,抗氧化、抗突变、抗菌抗病毒等生物活性,本文综述了红茶色素与红茶品质关系及生物学活性的研究进展。 相似文献
35.
36.
对黄土高原子午岭油松林不同管理方式下土壤的黑碳(BC)、有机碳(POC)和活性有机碳(LOC)的空间分布和积累进行了研究.结果表明,各种管理方式的油松林其POC、LOC和BC由表层至下层均呈显著的降低规律性.各种管理方式油松林0~10cm土层以BC>POC>LOC,10~20 cm土层中,天然油松林和粗放管理型油松林B... 相似文献
37.
实木制品的干缩湿胀性直接影响其尺寸稳定性,对白蜡木、黑胡桃木和橄榄木的干缩湿胀特性研究结果表明:三种木材全干状态下的体积干缩率分别为13.88%、10.85%、9.89%,气干状态下的体积干缩率分别为4.89%、4.71%、4.14%,气干至饱水状态下的体积湿胀率分别为18.28%、12.82%、11.54%,全干至气干状态下的体积湿胀率分别为5.94%、4.20%、3.96%。三种木材中白蜡木的干缩湿胀性最强,黑胡桃木次之,橄榄木最小。研究结果对实木制品用材含水率的控制具有一定的指导意义。 相似文献
38.
自20世纪80年代起,云南保山潞江坝胡椒种植面积逐渐萎缩,经调查分析,该地区冬春季节低温干旱的气候条件、管理粗放、连作障碍等导致胡椒旱衰和死亡是种植面积大幅萎缩的主要原因;作者在此基础上提出了该区胡椒产业发展的建议。 相似文献
39.
Jili Provincial Academy of Forestry Science Hongshi Forestry Bureau of Jili Province 《吉林林业科技》1994,(1):1-6
特种黑木炭是用柞、槲烧制的具有较高密度的木炭。影响黑木炭密度的主要因素有原料含水率和径级、干燥与炭化速度、炭窑窑形及精炼。本文还对烧制特种黑木炭过程中的具体操作技术要点进行了详尽的论述。 相似文献
40.
A field study was conducted for six years (1981–1986) on sandy loam soil on intercropping hedgerows of Leucaena leucocephala (Lam) de Wit. with three field crops viz. maize (Zea mays L), black gram (Vigna mungo L) and cluster bean (Cyamopsis tetragonoloba L Taub.). In treatments 1 and 2 Leucaena hedges were planted as pure crops at close (25 cm × 75 cm) and wide (25 cm × 375 cm) spacings. In treatments 3, 4 and 5 the
three field crops were intercropped between the hedgerows of Leucaena at the wide spacing, and in treatments 6, 7 and 8 the field crops were raised as pure crops. Leucaena was topped to 75 cm each time it attained a height of 175 cm.
The pure crop of Leucaena at close spacing produced an average, over the six years, of 34 t ha−1a−1 of green fodder and 9.4 t ha−1a−1 of air dry fuelwood. The Leucaena at wide spacing produced 18.9 t ha−1a−1 of green fodder and 6.3 t ha−1a−1 of fuelwood. Intercropping with field crops decreased the yield of green fodder and fuelwood. The yield of all the field
crops was less when raised as intercrops than as pure crops.
Mean maximum net returns were obtained from intercrops of Leucaena and cluster bean (Rs 3540 ha−1a−1) which were significantly higher than the returns from pure crop of Leucaena at wide spacing but similar to the returns from pure crops of cluster bean. Leucaena with maize (Rs 3273 ha−1a−1) and black gram (Rs 3125 ha−1a−1) gave significantly higher net returns over pure crops of Leucaena at wide spacing, maize and black gram.
ICRISAT = International Crops Research Institute for the Semi-Arid Tropics- Hyderabad, India.
CIAT = Centro International de Agricultura Tropical - Cali - Columbia 相似文献