Fiber hemp (Cannabis sativa L.) yield and its response to fertilization and planting density in China

This paper reports on a 3-year agronomic study into fibre hemp (Cannabis sativa L.) conducted in Tasmania, Australia. The performance of selected hemp cultivars, and the responses to sowing date and plant density were investigated as part of a broad feasibility study to assess the potential of fibre hemp and flax (Linum usitatissimum L.) as sources of fibre for the Australian newsprint industry. Trials were conducted at separate sites in north-west and south-east Tasmania. Nine cultivars from the Ukraine, Hungary and France were examined in 2 separate trials. The Hungarian cultivars, Kompolti and Unico B, and the French cultivar Futura 77 had the highest single plot dry stem yields (up to 1500 g/m 2 ) and bark proportions (up to 40%). All the cultivars flowered toward the end of January, suggesting that the growing season in Tasmania could accommodate much later flowering and potentially higher yielding genotypes. Levels of the psychoactive agent, delta-9-tetrahydrocannabinol were consistently below the legal maximum of 0.35% (dry weight basis). Three sowing date trials were conducted across 2 seasons incorporating dates between mid September and mid November and a single autumn planting at the end of May. Interactions with cultivar and planting density were also considered. Stem and bark yield declined with delays in sowing after early–mid October in response to a decline in calendar days and thermal time from sowing to flowering. The response was most pronounced in sowings of Kompolti, which flowered within a short period and differed more substantially in durations to flowering. Earlier sowings were limited by premature flowering in response to shorter daylengths and by poor drainage at one of the 2 trial sites. The success of early sowings in Tasmania would appear to depend on finding cultivars less sensitive tophotoperiod, and cultivation on well drained sites. A further trial was conducted to investigate the influence of plant density on hemp yields. Treatments included densities from 50 to 300 plants/m 2 . Plant density declined with crop growth across all treatments and was most pronounced for populations of 200 and 300 plants/m 2 . Final harvest stem yield responded in a parabolic manner to plant density, with maximum yields at about 110 plants/m 2 . Differences in the percentage of the long, high quality bark fibre at final harvest were generally small and not significant. However, regression analysis of the response of bark percentage suggested a linear decline with increasing initial density.

Download Full-text

Planting Density and Fertilization Evidently Influence the Fiber Yield of Hemp (Cannabis sativa L.)

Agronomy ◽

10.3390/agronomy9070368 ◽

2019 ◽

Vol 9 (7) ◽

pp. 368 ◽

Cited By ~ 1

Author(s):

Gang Deng ◽

Guanghui Du ◽

Yang Yang ◽

Yaning Bao ◽

Feihu Liu

Keyword(s):

Cannabis Sativa ◽

Application Rate ◽

Planting Density ◽

High Yield ◽

Nitrogen Application ◽

Potassium Fertilizer ◽

Hemp Fiber ◽

Fiber Yield ◽

Potassium Application ◽

Phosphorus Application

Hemp is one of the most important green (i.e., environmentally sustainable) fibers. Planting density, nitrogen (N), phosphorus (P) and potassium (K) significantly affect the yield of hemp fiber. By optimizing the above main four cultivation factors is an important way to achieve sustainable development of high-fiber yield hemp crops. In this study, the effects of individual factors and factor × factor interactions on the yield of hemp fiber over two trial years were investigated by the central composite design with four factors, namely planting density, nitrogen application, phosphorus application, and potassium application rate. The influences of these four test factors on the yield of hemp fibers were in the order nitrogen fertilizer (X2) > planting density (X1) > potassium fertilizer (X4) > phosphate fertilizer (X3). To obtain yields of hemp with high-quality fiber greater than 2200 kg ha−1, the optimal range of cultivation conditions were planting density 329,950–371,500 plants/ha, nitrogen application rate 251–273 kg ha−1, phosphorus application rate 85–95 kg ha−1, and potassium application rate 212–238 kg ha−1. This study can provide important technical and theoretical support for the high-yield cultivation of hemp fiber into the future.

Download Full-text

Cannabis und Schizophrenie

SUCHT - Zeitschrift für Wissenschaft und Praxis / Journal of Addiction Research and Practice ◽

10.1024/suc.2002.48.5.336 ◽

2002 ◽

Vol 48 (5) ◽

pp. 336-345 ◽

Cited By ~ 3

Author(s):

Jürgen Seifert ◽

Jann Schlimme ◽

Felix Wedegärtner ◽

Hinderk M. Emrich ◽

Udo Schneider

Keyword(s):

Cannabis Sativa ◽

Cannabinoid System ◽

Psychotische Störungen

Überblick: Cannabis sativa ist eine der ältesten medizinischen Heilpflanzen. In den westlichen Kulturen wird Cannabis überwiegend als Freizeitdroge angesehen. Im Harz sowie in den Blüten der weiblichen Pflanze findet sich ein Gemisch aus verschiedenen psychoaktiven Inhaltsstoffen. Am bedeutendsten ist in diesem Zusammenhang das delta-9-Tetrahy-drocannabinol. </P><P> Epidemiologie: Nicht selten werden die Gefahren des Cannabiskonsums, wie z. B. die Möglichkeit der Induktion einer Psychose unterschätzt. Wenn man jedoch berücksichtigt, wie häufig z. B. Jugendliche THC konsumieren, ist die Frage, ob Cannabis eine Psychose aus dem schizophrenen Formenkreis de novo induzieren kann, von besonderem gesundheitspolitischem und volkswirtschaftlichem Interesse. Die Datenlage ist allerdings nach wie vor unklar. Die klinisch-epidemiologischen Studien deuten aber darauf hin, dass Cannabiskonsum bei vulnerablen Personen schizophrenieforme Psychosen auslösen kann und einen ungünstigen Krankheitsverlauf zur Folge hat. </P><P> Das endogene Cannabinoid-System: Die vorliegende Arbeit gibt außerdem einen Überblick der Publikationen, die sich mit dem körpereigenen Cannabinoid- System und seinen endogenen Liganden im Hinblick auf psychotische Störungen beschäftigen.

Download Full-text