ASSESSMENT OF STEM PRODUCTION IN SOME VARIETIES OF DIOECIOUS HEMP Anca

. Varieties of dioecious hemp (Cannabis sativa L) created at ARDS Lovrin, Lovrin-110, Silvana, Armanca and Teodora, is characterized by the production of strains exceeding 10 t/ha, a fiber content of 25-30 % and can be extended in culture both in our country and in the European Union and not only, due to a low THC content below 0.2%. Dioecious hemp varieties exhibit a high ecological plasicity, when applying appropriate technology they achieve high yields. The researches carried out in the field of cultivation of dioecious hemp in Romania, for stems and seeds, have shown that it can be used in various industries (textile, cellulose, food, etc.) from where to result in high quality products. Following the study undertaken in the period 2021-2022, at ARDS Lovrin, it can be concluded that the variety Armanca has the highest yield of stems per hectare, with an increase of 2373.5 kg/ha, 29.1% more than the yield obtained by the control variety Silvana.


INTRODUCTION
Hemp originated in Central and Eastern Asia as well as the region in northwestern China mentioned thousands of years ago, where various forms of wild hemp are found (Ceapoiu, 1958). It then spread to Europe where it reached two paths, the northern road and the southern road, the northern long-day hemp comes from the northern road , and the southern one of the short day comes from the southern road. The large hemp-growing countries in the world are Russia, India, the U.S.A., Poland, Romania, Hungary, Bulgaria, France, Italy Czechoslovakia, Germany, with large fluctuations in the periods in which the crop was banned.
In Romania, researches have been carried out on hemp culture, for stems and seeds (Găucă et al, 1987, Paraschivoiu Rodica, 1987, Tabără, 1981, 1985, Șandru et all, 1996, by obtaining varieties of dioecious hemp as well as varieties of monoecious hemp. Due to the low THC content below 0.2%, hemp varieties can be extended in culture both in our country, in the European Union and not only (Tabără, 2005, Amaducci et al, 2015, Bîlteanu, 2001.
The wood resulting from hemp stalks is a good fuel, it is also useful as a raw material in the pulp industry, by applying a specific technology applied, for the manufacture of certain types of paper (Rivoira, 1981, Bonciarelli, 1998. From the plethora resulting from the separation of the woody part from the fiber, the particle board successfully used in the furniture industry and in construction with sound-insulating and thermal insulating properties can be manufactured (Tabără, 2005, Forgo, 1957, Bertoli, 2010.
As for pests, hemp shows a fairly good tolerance to the attack of insects. However, the attack of grapholita delineana species leads to the depreciation of fibers and seeds.
Studies carried out on varieties created at ARDS Lovrin, revealed a different behavior of varieties at the attack of this pest.
After Cotuna (Cotuna et al, 2020), on the organs of the analyzed hemp plants, the larvae show an uneven distribution. In the same study, large differences were observed between male and female plants regarding the intensity of the attack of the hemp moth, being known that, this pest has a preference for female inflorescences. In the four varieties created at ARDS Lovrin, differences in the attack of the hemp moth to the stems were observed, and they were also preferred by this pest. The highest densities of the larvae on the stem were observed in the Teodora variety followed by the Armanca variety, and the lowest in the Lovrin 110 and Silvana varieties (Cotuna et al., 2020).
And hemp, like other crop plants, is strongly influenced by the technological factor, in terms of crop productivity and quality (Agapie, 2016). Among the links in technology, fertilization significantly influences the growth and development of plants, the coefficient of use of active substances in fertilizers being influenced at its root by the type of fertilizer used, by the periods of application and by the climatic conditions of the respective agricultural year (Agapie, 2021).
According to Ceapoiu and collaborators, it is shown that chemical fertilizers have the most dynamic contribution to the increase of the production of hemp stalks, phased by a basic fertilization and additional fertilization during the growing season. Nitrogen being requested by hemp in the largest quantities, on all soil types, increasing not only the production of stems but also that of fiber and seed (Ceapoiu, 1958, Segărceanu, 1978. The same authors point out that nitrogen has the main role in increasing the production of stems per hectare, applied in high doses prolongs the vegetation period by 6-10 days, unilaterally applied nitrogen causes a large increase in the production of stems and an insignificant increase in fiber production.
The varieties of dioecious hemp created at ARDS Lovrin have a high production capacity of over 10.000 kg/ha stems therefore can provide raw material for the textile industry and beyond.

MATERIAL AND METHODS
The study conducted on the evaluation of the production of strains in four varieties of dioecious hemp, was carried out over a period of two years at ARDS Lovrin. The technology specific to the hemp crop for fiber has been applied. The time of sowing was achieved when in the soil there was a temperature of 7-8⁰C in the morning, at a depth of 5-6 cm. In the field of the laboratory for the improvement of dioecious hemp, the biological material, was sown at a distance of 12.5 cm between the rows and at a density of 450 germinable grains per square meter, the sowing depth between 3-5 cm. Harvesting was done when the last pollen is shaken at the time of technical maturity, the stems of the male plants are yellow-green or yellow in color and the leaves have dried and fallen. Monofactorial experience the factor pursued is the variety/varieties of the genotypes studied taken in the study, was chosen as the witness of the dioecious hemp variety Silvana.
The statistical interpretation of the obtained data was performed according to the variance analysis method, ANOVA (using the Poly Fact program).
The climatic conditions of 2020 and 2021 were characterized based on the weather records existing at the Lovrin Agricultural Research and Development Station. The climatic conditions during this period are shown in Figure 1 and Figure 2.
The data recorded at the Lovrin Meteorological Station for the agricultural year 2020-2021, reveals an increase in the average annual temperature by 1.4⁰C compared to the multiannual average, the alarming increase in temperature in the winter and spring months, faithfully reproduced in the last 10 years and the uneven distribution of precipitation during the growing season of the crops, with unfavorable effects on the recovery of the administered inputs, the growth and the development of the plants. From the analysis of the data on the pluviometric regime, from the agricultural year 2020-2021, it results that in its assembly was an atypical year, the quantities of water coming from precipitation ( Fig.1) recording values around the multiannual monthly average in the spring months. Drought installed since March, as a result of uneven distribution of precipitation (total lack of precipitation above 2 mm in the range 15.03.2021 -20.05.2021), amplified by the atmospheric heat, the intensification of the wind speed and the large temperature difference between day and night) have significantly affected the crops.

RESULTS AND DISCUSSIONS
The varieties analyzed in this study -Silvana, Lovrin-110, Armanca and Teodora, are varieties created and approved at ARDS Lovrin for the fiber content of the stems. With this in mind, the yield of stems obtained per hectare is an indicator that significantly influences the production of fiber per hectare.
Thus, in this material, we present the production of dioecious hemp stalks obtained in climate and soil conditions from ARDS Lovrin.
In the following tables (Tab. 1 and 2), the production of stems obtained in the climatic conditions of 2021 is shown. Analyzing the presented data, it is noticed the superiority of the varieties Lovrin-110, Armanca and Teodora, compared to the control variety Silvana. The production of strains varies in the range of 5378 kg/ha (Silvana) -10356 kg/ha (Armanca), with production increases belonging to the range 3511 -4978 kg/ha. The production increases obtained are statistically distinctly significant and very significant for the transgression probabilities of 1% and 0.1%.
In the climatic conditions of 2022, the production of strains presented in the following tables (Tab. 3 and 4), values in the range of 10729 kg/ha and 11969 kg/ha are recorded. Compared to the control variant, the Lovrin-110 variety is superior in terms of stem production, the difference between the two varieties being 9.2%.
The lowest yield is obtained for the Armanca variety, which has an increase below the control -231 kg/ha, 2.1% less. As regards the average production for the period 2021-2022 (Tab.5 and Fig. 3), it is noted the superiority of the Armanca variety, with an increase of 2373.5 kg/ha (29.1%), followed by the Lovrin-110 variety with an increase of 2260 kg/ha (27.7%) and the Teodora variety respectively 1979.5 kg/ha (24.2%).