ABSTRACT
The present study aimed to explore the effects of exogenous gibberellins (GAs) on seed germination and subsequent seedling growth of hemp (Cannabis sativa L.) under drought stress. Seeds of two industrial hemp cultivars i.e., 'Yunma 1', (YM) and 'Bamahuoma', (BM) were treated with different concentrations of GA3 solution (0, 200, 400, 600, 800 mg/L) at 20 °C for 8 h. The effect of pre-treatment was assessed on germination characteristics and physiological indexes on subsequent exposure to drought stress using 20% (m/v) polyethylene glycol (PEG) for 7 days. The results revealed that seed germination in hemp was sensitive to drought stress, as the germination indexes (germination rate and germination potential) decreased significantly, and seedling growth (hypocotyl length and radicle length) was impeded under 20% PEG-6000 condition. GA3 pre-treatment affected germination rate, germination potential, hypocotyl length and radicle length. With increasing GA3 concentration, these indexes first increased and then decreased. For seedling physiology characteristics in hemp, GA3-pretreatment remarkedly increased the osmotic regulating substances (soluble sugar and soluble protein contents) and the activities of antioxidant enzymes (SOD, superoxide dismutase and POD, peroxidase), while sharply decreased the lipid peroxidation (malondialdehyde, MDA) in seedlings grown under PEG-6000 induced drought stress. These results suggested that seeds pre-treated with GA3 could enhance the drought tolerance of hempseeds, and the optimal effect of GA3 for seed pre-treatment of YM and BM could be obtained when the concentration of GA3 solution reached 400 mg/L and 600 mg/L, respectively.
ABSTRACT
Rising human population has increased the utilization of available resources for food, clothes, medicine, and living space, thus menacing natural environment and mounting the gap between available resources, and the skills to meet human desires is necessary. Humans are satisfying their desires by depleting available natural resources. Therefore, multifunctional plants can contribute towards the livelihoods of people, to execute their life requirements without degrading natural resources. Thus, research on multipurpose industrial crops should be of high interest among scientists. Hemp, or industrial hemp, is gaining research interest because of its fastest growth and utilization in commercial products including textile, paper, medicine, food, animal feed, paint, biofuel, biodegradable plastic, and construction material. High biomass production and ability to grow under versatile conditions make hemp, a good candidate species for remediation of polluted soils also. Present review highlights the morphology, adaptability, nutritional constituents, textile use, and medicinal significance of industrial hemp. Moreover, its usage in environmental conservation, building material, and biofuel production has also been discussed.
Subject(s)
Cannabis , Allergens , Animals , Biofuels , Biomass , Humans , IndustryABSTRACT
Hemp (Cannabis sativa L.) is a bast-fiber crop well-known for the great potential to produce sustainable fibers. Nevertheless, hemp fiber quality is a complex trait, and little is known about the phenotypic variability and heritability of fiber quality traits in hemp. The aim of this study is to gain insights into the variability in fiber quality within the hemp germplasm and to estimate the genetic components, environmental components, and genotype-by-environment (G×E) interactions on fiber quality traits in hemp. To investigate these parameters, a panel of 123 hemp accessions was phenotyped for 28 traits relevant to fiber quality at three locations in Europe, corresponding to climates of northern, central, and southern Europe. In general, hemp cultivated in northern latitudes showed a larger plant vigor while earlier flowering was characteristic of plants cultivated in southern latitudes. Extensive variability between accessions was observed for all traits. Most cell wall components (contents of monosaccharides derived from cellulose and hemicellulose; and lignin content), bast fiber content, and flowering traits revealed large genetic components with low G×E interactions and high broad-sense heritability values, making these traits suitable to maximize the genetic gains of fiber quality. In contrast, contents of pectin-related monosaccharides, most agronomic traits, and several fiber traits (fineness and decortication efficiency) showed low genetic components with large G×E interactions affecting the rankings across locations. These results suggest that pectin, agronomic traits, and fiber traits are unsuitable targets in breeding programs of hemp, as their large G×E interactions might lead to unexpected phenotypes in untested locations. Furthermore, all environmental effects on the 28 traits were statistically significant, suggesting a strong adaptive behavior of fiber quality in hemp to specific environments. The high variability in fiber quality observed in the hemp panel, the broad range in heritability, and adaptability among all traits prescribe positive prospects for the development of new hemp cultivars of excellent fiber quality.
ABSTRACT
Interest in hemp (Cannabis sativa L.) as a crop for the biobased economy is growing worldwide because hemp produces a high and valuable biomass while requiring low inputs. To understand the physiological basis of hemp's resource-use efficiency, canopy gas exchange was assessed using a chamber technique on canopies exposed to a range of nitrogen (N) and water levels. Since canopy transpiration and carbon assimilation were very sensitive to variations in microclimate among canopy chambers, observations were adjusted for microclimatic differences using a physiological canopy model, with leaf-level parameters estimated for hemp from our previous study. Canopy photosynthetic water-use efficiency (PWUEc), defined as the ratio of gross canopy photosynthesis to canopy transpiration, ranged from 4.0 mmol CO2 (mol H2O)-1 to 7.5 mmol CO2 (mol H2O)-1. Canopy photosynthetic nitrogen-use efficiency (PNUEc), the ratio of the gross canopy photosynthesis to canopy leaf-N content, ranged from 0.3 mol CO2 d-1 (g N)-1 to 0.7 mol CO2 d-1 (g N)-1. The effect of N-input levels on PWUEc and PNUEc was largely determined by the N effect on canopy size or leaf area index (LAI), whereas the effect of water-input levels differed between short- and long-term stresses. The effect of short-term water stress was reflected by stomatal regulation. The long-term stress increased leaf senescence, decreased LAI but retained total canopy N content; however, the increased average leaf-N could not compensate for the lost LAI, leading to a decreased PNUEc. Although hemp is known as a resource-use efficient crop, its final biomass yield and nitrogen use efficiency may be restricted by water limitation during growth. Our results also suggest that crop models should take stress-induced senescence into account in addition to stomatal effects if crops experience a prolonged water stress during growth.
