Hemp (
Cannabis sativa
L.) is a multiuse plant, which has been abundantly studied for phytoremediation purposes in recent years. The majority of experiments were performed in greenhouses with potted ...plants where hemp showed promising results. Only few studies tested hemp on site in heavy metal–polluted agricultural soil in real environmental conditions and practical assessments of hemp phytoremediation feasibility are lacking. We conducted a comprehensive study using 2 legal industrial hemp varieties (Futura 75 and Tisza) at three differently polluted locations (heavily polluted location, HP; moderately polluted location, MP; and slightly polluted location, SP) in the heavy metal contaminated Celje valley in Slovenia and determined the content of Pb, Zn, and Cd in 5 plant organs/tissues. The yield of each organ/tissue was determined as well to enable us to calculate the phytoremediation potential (PP). On average, plants grown in the HP location accumulated the highest values of all examined elements, followed by plants from the MP location and plants from the SP location, showing that the content of heavy metals in soil influences the accumulation in plants. Accumulation of Pb/Zn/Cd by plant organs/tissues was distributed in the following order: inflorescences (Pb-4.10/Zn-92.8/Cd-0.50 mg/kg) > seeds (Pb-1.79/Zn-92.6/Cd-0.27 mg/kg) > roots (Pb-1.15/Zn-15.0/Cd-0.44 mg/kg) > stem bark (Pb-0.42/Zn-12.4/Cd-0.23 mg/kg) > stem woody core (Pb-0.34/Zn-4.6/Cd-0.15 mg/kg). The only exception was for Cd, where roots accumulated a higher value than seed, yet lower than inflorescences. PP was calculated by multiplying hemp tissue/organ yield by the relative concentrations of heavy metal. The highest PP for Pb and Cd were achieved at the HP location (3.80 and 0.23 g/ha/vegetation period). On the other hand, tissue/organ yield was more important for high PP of Zn, where the SP location reached the highest PP for Zn (148.5 g/ha/vegetation period) due to the highest yields. Only seeds from HP and MP locations accumulated a too high content of Pb; otherwise, all other fibers and seeds can be safely used in the textile and food industry. Results of this study showed that hemp cannot be considered an efficient plant for the phytomanagement of contaminated areas. Nevertheless, hemp cultivation in heavy metal–polluted agricultural soils seems feasible since the majority of tissues/organs were not contaminated and different products can be obtained from various parts of the hemp plant.
In plants, apical dominance prevents the development of lateral shoots. It can be overwhelmed by apical bud defoliation, allowing numerous lateral buds to develop into more lateral branches carrying ...more fruits and possibly increasing seed yield. This study tested this hypothesis on five hemp (Cannabis sativa L.) cultivars in a 2-year field experiment. In comparison to the intact ones, the defoliated plants developed several lateral shoots. The hemp seed yield was significantly influenced by the year of production, the apical bud removal, and the cultivar. The average two-year seed yield of the defoliated plants (715 ± 47 kg/ha) was significantly higher than the yield of the intact plants (568 ± 35 kg/ha). Absolutely the greatest effect of apical bud removal on the seed yield was observed for the cultivar 'Novosadska konoplja', where increase was 225 kg/ha (25%); a slightly smaller difference occurred for the cultivar 'Uniko-B' (183 kg; 30%), followed by 'Juso-11' (140 kg/ha; 27%) and 'Bialobrzeskie' (128 kg/ha; 29). Cultivar 'Beniko' presented the smallest difference with apical bud removal - 58 kg/ha (15%) yield increase We maintain that hemp producers can achieve a larger seed yield not only by selecting an appropriate cultivar and row distance but also by removing apical buds.
Aims
Soils represent the natural habitat of entomopathogenic nematodes (EPNs). When moving in soil, EPNs are oriented to follow a chemical signal (chemotaxis).
Cannabis sativa
L. is known to secrete ...a very wide spectrum of secondary metabolites. Ethanol extracts (EE) of different
C. sativa
L. organs were used to study the effect on EPN chemotaxis.
Methods
The root, leaf and inflorescence EE of two hemp varieties and two medical cannabis breeding lines were used in laboratory chemotaxis assays with three EPN species (
Steinernema carpocapsae
,
S. feltiae
and
Heterorhabditis bacteriophora
) at 20 and 25 °C. The content of terpenes and cannabinoids in
C. sativa
L. inflorescences was measured as well.
Results
Overall, EPNs were most attracted or repelled by inflorescence extracts, followed by leaves and roots. The most abundant terpene in hemp inflorescences was trans caryophyllene (38.2% on average), the highest contents of total cannabidiol, total cannabigerol and total tetrahydrocannabinol were 9.65%, 0.89% and 0.62%, respectively.
Conclusions
The attraction effect of
S. sativa
L. EE is a highly interesting outcome and could lead to the development of attractant compounds in EPN biological control. Cannabinoids and terpenes may be responsible for pronounced effects on EPN chemotaxis.
Sowing of bacterial inoculated seeds and using different cultivar-specific row spacing are 2 well-known agricultural practices in soybean production. However, the connection between different ...bacterial seed inoculations and row spacing has not previously been investigated in a single study. A 3-year field experiment (2015–2017) was carried out on soybean cv. ES Mentor to assess the effect of 4 rhizobia inoculation treatments (un-inoculated control, C; factory-inoculated seed, F; fresh pre-sowing seed treatment with commercial inoculant, I; and a combination of treatments F and I, FI) and 3 row spacings (12.5 cm, 25 cm and 37.5 cm) on the protein, oil, crude fibre and ash content. The seed, protein and oil yields were determined as well as a thousand seed weight, plant height, pod number and harvest index. There was no interaction between plant spacing and inoculation; however, the inoculation treatments enhanced protein content of seeds by 1.2–1.7%, and increased yields of seed, protein and oil by a maximum of 6.8%, 8.3% and 5.9%, respectively, compared to the un-inoculated control, which produced an average seed yield of 4098 kg/ha. The inoculation treatments also had a moderate influence on biometric measurements. Row spacing had a pronounced effect on seed, protein and oil yields, with plants in 12.5 cm and 25 cm row spacings generating higher yields than those in 37.5 cm row spacings. Correlation analysis showed a significant positive association between seed yield and pod number, and a significant negative correlation between protein and oil content.
Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) and common buckwheat (Fagopyrum esculentum Moench) are adapted to growing in harsh conditions of high altitudes. Ultraviolet radiation at high ...altitudes strongly impacts plant growth and development. Under the influence of ultraviolet radiation, protecting substances are synthesized in plants. The synthesis of UV-B defense metabolites is genetically conditioned, and their quantity depends on the intensity of the ultraviolet radiation to which the plants and plant parts are exposed. These substances include flavonoids, and especially rutin. Other substances with aromatic rings of six carbon atoms have a similar function, including fagopyrin, the metabolite specific for buckwheat. Defensive substances are formed in the leaves and flowers of common and Tartary buckwheat, up to about the same concentration in both species. In comparison, the concentration of rutin in the grain of Tartary buckwheat is much higher than in common buckwheat. Flavonoids also have other functions in plants so that they can protect them from pests and diseases. After crushing the grains, rutin is exposed to contact with the molecules of rutin-degrading enzymes. In an environment with the necessary humidity, rutin is turned into bitter quercetin under the action of rutin-degrading enzymes. This bitterness has a deterrent effect against pests. Moreover, flavonoids have important functions in human nutrition to prevent several chronic diseases, including obesity, cardiovascular diseases, gallstone formation, and hypertension.
The grains of three barley varieties were milled and sieved to obtain respective milling fractions with a content of beta-glucans (b-G) from 1.4 to 10.7%. The enriched fraction obtained by the ...extraction and precipitation contained 24.7% of b-G. The differences between the ratio of stable C carbon isotopes were established. Milling fractions with coarse particles had more beta-glucans and a more negative ratio of δ
C isotope in comparison to the respective intact barley grain. However, the enriched fraction had a less negative isotope ratio. So, it is not expected that the deviation from the stable isotope ratio of grain in milling fractions is the result of the content of b-G, but it depends on other barley grain constituents. In different parts of barley grain, there are substances with different stable isotope ratios, and by milling and sieving, they are assorted to the same milling fraction with most of the b-G. The method for determining the ratio of a stable carbon isotope in diverse barley grain fractions, applied in this investigation, is potentially opening the possibility for an additional method of screening the concentration of bioactive constituents in barley grain.
Optimal planting speed of vacuum maize planters is usually suggested by planter’s manufacturers, while increased planting speed may influence plant spacing and finally yield. Our hypothesis was that ...by increasing planting speed over the suggested level plant spacing variability will also increase which will result in decrease of silage and grain yield and saving of seed and energy. The field trial consisted of three planting speeds of 7, 9 and 11 km/h in the form of random blocks. The following measurements were taken as follows: plant spacing, silage and grain yield, fuel and energy use at planting. Results in this study show that planting speed did not have significant influence on silage and grain yield of maize, while up to 10% less seed was needed per hectare and fuel and energy use was lower for 15%. By the increase of planting speed the distance between the plants in a row, and in most cases also the plant spacing variability increased. It was noticed that by increasing planting speed plant density decreased. This research established that at higher planting speeds significant increase of the silage yield per individual plant and of the grain yield per individual plant was achieved. The ear parameters also show that the kernel mass per individual ear, the ear mass, and the cob mass, as well as the individual kernel mass, are larger at the planting speed of 11 km/h than at the planting speed of 7 km/h. At the latter planting speed, significantly higher fuel consumption per hectare and higher energy use was achieved than at the other two planting speeds. Overall the main benefits of planting speed of 11 km/h is saving seed and energy at planting while maintaning the same level of silage and grain yield compared to lower planting speeds used in the trial. Highlights - Planting speed of vacuum planter did not influence the silage and grain yield of maize. - At a higher planting speed up to 10% less seed was needed per hectare and fuel and energy use was reduced up to 15%. - Silage and grain yield per individual plant increased by increasing planting speed. - Increasing of planting speed plant density decreased. - Plant spacing parameters were significantly affected by planting speed.
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