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Effect of drip irrigation on yield and evapotranspiration of fibre hemp (Cannabis sativa L.)

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Summary: The experiments showing the effect of drip irrigation on yield and evapotranspiration of fibre hemp (Cannabis sativa L.) were conducted at the experimental field of the Alternative Crops Department, Institute of Field and Vegetable Crops, Novi Sad, Serbia. Irrigation was based on the water balance method. Daily evapotranspiration (ETd) was computed from the reference evapotranspiration (ETo) and crop coefficient (kc) 0.5, 0.9 and 1.1 from sowing to 3-4 pair of leaves, from 3-4 pair of leaves to appearance of male flowers and from appearance of male flowers to the end of the season, respectively. ETo was calculated using Hargreaves equation. The irrigation depth was restricted to the soil depth of 0.4 m. In other words, irrigation started when readily available water in the soil layer of 0.4 m was completely depleted by plants. The irrigation rate was 30 mm at the beginning of the season, 40 mm in the middle of the season, and the amount of water added by irrigation was 320 mm during the entire season. Irrigation significantly affected the yield of fresh stems, fresh leaves, flowers and plant height, but not stem diameter and fibre content. Water used on evapotranspiration in irrigation conditions (ETm) was 470 mm, while in non-irrigated control variant it amounted to 129 mm (ETa). These preliminary results could be used as a good platform for hemp growers in the region, in terms of optimizing the use of irrigation water. Key words: Cannabis, evapotranspiration, hemp, irrigation
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Summary: The experiments showing the effect of drip irrigation on yield and evapotranspiration of fibre hemp
(Cannabis sativa L.) were conducted at the experimental field of the Alternative Crops Department, Institute of Field
and Vegetable Crops, Novi Sad, Serbia. Irrigation was based on the water balance method. Daily evapotranspiration
(ETd) was computed from the reference evapotranspiration (ETo) and crop coefficient (kc) 0.5, 0.9 and 1.1 from
sowing to 3-4 pair of leaves, from 3-4 pair of leaves to appearance of male flowers and from appearance of male
flowers to the end of the season, respectively. ETo was calculated using Hargreaves equation. The irrigation depth was
restricted to the soil depth of 0.4 m. In other words, irrigation started when readily available water in the soil layer of
0.4 m was completely depleted by plants. The irrigation rate was 30 mm at the beginning of the season, 40 mm in the
middle of the season, and the amount of water added by irrigation was 320 mm during the entire season. Irrigation
significantly affected the yield of fresh stems, fresh leaves, flowers and plant height, but not stem diameter and fibre
content. Water used on evapotranspiration in irrigation conditions (ETm) was 470 mm, while in non-irrigated control
variant it amounted to 129 mm (ETa). These preliminary results could be used as a good platform for hemp growers in
the region, in terms of optimizing the use of irrigation water.
Key words: Cannabis, evapotranspiration, hemp, irrigation
Hemp (Cannabis sativa L.) is an annual herbaceous
flowering plant indigenous to eastern Asia but now of
cosmopolitan distribution due to widespread
cultivation. It has been cultivated throughout recorded
history, used as a source of industrial fibre, seed oil,
food, recreation, religious and spiritual moods and
medicine. Each part of the plant is harvested differently,
depending on the purpose of its use. Hemp is used to
make a variety of commercial and industrial products
including rope, clothes, food, paper, textiles, plastics,
insulation and biofuel.
Hemp is an annual plant grown in temperate
zones. It is mainly present in the eastern hemisphere. In
Corresponding author:
ksenija@polj.uns.ac.rs
Acknowledgment:
This study was supported by Ministry of Education, Science and Technological
Development, Republic of Serbia (Project TR31016 Improvement of field
forage crops agronomy and grassland management).
the world industrial hemp is grown on the area of
105,576 ha. The five biggest hemp producing countries
in the world are China, North Korea, Chile, France,
Germany, and Great Britain. In Serbia industrial hemp
occupies the area of about 200 ha (FAO, 2004). Hemp
requires a frost-free season of minimum 130 days,
middle summer temperatures and a fertile ground
(White et al., 1964).
In Vojvodina region, the hemp is cultivated only
under rainfed conditions; there is no recorded data on
its cultivation under irrigation. Studies conducted in a
wide range of environments confirm that irrigation
could seriously influence the yield of fibre hemp (Lisson
and Mendham, 1998; Di Bari et al., 2004). Hacket (1991)
defined water stress as the most limiting factor affecting
the fibre yield and quality.
Preliminary step to a more intensive exploitation of
the available agroecological conditions or to the
development of irrigation schedules for any crop implies
a study of crop requirements for water, i.e. the
evapotranspiration (ET) for any particular crop. In
order to fully utilize the genetic yield potentials of fibre
hemp and achieve high and stable yields, it is necessary
to gain knowledge of the crops capabilities under
conditions of dry farming and irrigation. Literature
recommendations for the water requirements of fibre
hemp are sparse and ambiguous. In growing period,
hemp needs 250-350 mm of rainfall (Kišgeci, 1994). In
Ukraine, optimum yields are achieved with 250-280 mm
of rainfall during the growing season. Van Dam (1995)
reported that hemp requires rainfall of at least 650 mm
per year in the Netherlands climate. Lisson and
Mendham (1998) reported that the highest yield of
hemp fibre was obtained with water consumption of
535 mm during growing season in northwest Tasmania
in Australia. Bócsa and Karus (1998) reported much
higher water requirements of hemp up to 700 mm,
especially during the rapid growth phase.
The objective of the study was to get information
of how the plants of fibre hemp react to irrigation as
well as determination of fibre hemp evapotranspiration
in agroecological conditions of the Vojvodina region.
The experiment with irrigated hemp was
conducted in 2017 at Bački Petrovac experimental field
of Institute of Field and Vegetable Crops in Novi Sad,
Serbia (N 45° 19`, E 19° 50`) on the calcareous
chernozem soil on the loess terrace. In the period 1964-
2016, the annual mean air temperature, precipitation and
relative humidity were 11.2oC, 598.7 mm and 76%
respectively. According to the Hargreaves climate
classification system, the study area is classified as arid
in the summer period, from June to August (Bošnjak,
2001). Hemp variety Helena was used for the trials. The
row spacing was 0.25 × 0.04 m. The size of the
experiment unit was 6.75 m2 (1.5 × 4.5 m) and was
replicated three times.
The trial was established as a blocks design and
adapted to technical specifications of drip irrigation
system. The plants were irrigated with a lateral placed in
every other row with drippers spaced every 0.1 m. The
distance between laterals was 0.5 m. Drippers had an
average flow of 1.0 l h-1 under a pressure of 70 kPa. The
trial included irrigated and non-irrigated, control
variants. Irrigation was scheduled on the basis of water
balance method using reference evapotranspiration
(ETo) and crop coefficients (kc). ETo was calculated by
Hargreaves equation (Hargreaves and Allen, 2003).
Daily water used on plants evapotranspiration (ETd) was
calculated by multiplying ETo with kc values 0.5 from
sowing to 3-4 pair of leaves, 0.9 from 3-4 pair of leaves
to appearance of male flowers, 1.1 from appearance of
male flowers to the end of the season (Cosentino et al.,
2012; García-Tejero et al., 2014). Irrigation started when
readily available water in the soil layer of 40 cm was
completely absorbed by plants. The irrigation rate was
30 mm at the beginning of the season and 40 mm in the
middle season. The volume of irrigation water and the
pressure in the system were measured by the flow meter
and the pressure gauge installed in the hose nozzle used
for irrigation.
ETo - reference evapotranspiration (mm day-1), Tm - the
average daily air temperature (oC), Tmax -the maximum
daily temperature (oC), Tmin - the minimum daily
temperature (oC), Ra - the extraterrestrial radiation (MJ
m-2 day-1)
ETd = ETo kc
All recommended agronomic practices were
applied for cultivation and plant protection at the
experimental site. Precipitation and air temperature data
were obtained from Meteorological Station located at
Bački Petrovac experimental field. Data reported for
fibre hemp yield were assessed by analysis of variance
(ANOVA) and Fisher’s LSD test was used to identify
significant differences at the p< 0.05 levels between the
mean values. Different letters indicate significant
differences between values.
In the growing season of 2017 (from 26 April to 12
August), the mean air temperature and total rainfall
were 22.6oC and 99 mm, respectively (Table 1). The
amount of water added by irrigation was 320 mm
(Figure 1, Table 1). Based on the calculated values of
water balance of hemp (Table 1) it can be concluded
that irrigation was applied on time with required
amount of water and that the deficit of readily available
water in the soil was completely eliminated. The
amount of irrigation water strongly depends on
environment and genotype. In semi-arid Mediterranean
environment the irrigation rate for early genotypes is at
least 250 mm and 450 mm for late genotypes
(Cosentino et al., 2013).
Rainfall shortages is the main problem for
successful hemp growth (Hackett, 1991) and therefore
irrigation is essential in hemp production as it could
overcome deficiencies in both the distribution and the
total amount of precipitation over the summer period
(Lisson and Mendham, 1998). Di Bari et al. (2004)
indicated that in the southern Italy irrigation is
indispensable for overcoming the prolonged water
deficit which hemp is subject during vegetation season.
They highlighted that the best results were obtained
with the reintegration of 66% of the water lost through
evapotranspiration.
Irrigation significantly affected yield of fresh stems,
fresh leaves and flowers and plant height, but not stem
diameter and fibre content. (Table 2). Irrigation
significantly increased the yield of fresh stem by 48,18%
and fresh leaves and flowers by 46,28%, with water
consumption of 470 mm. Lisson and Mendham (1998)
also pointed out that the stalk yield of hemp, total dry
matter, bark percentage and bark yield were significantly
higher when compared to rainfed treatment in
northwest Tasmania, Australia. Results of fibre content
in irrigation conditions of 32.1% are similar to those
obtained in Spain, reported by Lioveras et al. (2006).
In years with a pronounced water deficit in
Vojvodina, such as 2017, rainfall was not sufficient for
hemp production. For this reason, irrigation was needed
for acceptable yields of fibre hemp grown in the region.
In order to achieve the full potential of industrial
crops, the amount of irrigation water needs to be defined
(García-Tejero et al., 2014) with regard to hemp water
requirements defined on the basis of evapotranspiration.
Figure 1. Irrigation
schedules, irrigation
water applied and
meteorological data for
the experimental year
(daily rainfall and daily
average air temperature)
Elements
Sowing - 3-4 pair
of leaves
3 - 4 pair of leaves -
appearance of male
flowers
Appearance of male
flowers - and of the
season
Total/Average
26 IV-1 VI 1VI-1 VII 1VII-12 VIII 26 IV-12 VIII
ETo (mm) 143 163 165 471
ETm (mm) 72 147 251 470
Water used on ETm (%) 15.3 31.3 53.4 100
Duration (days) 36 31 43 110
ETd (mm) 2.0 4.7 5.8 4.3
Rainfall (mm) 57 14 28 99
Temperature (˚C) 18.1 23.9 25.8 22.6
Δ -15 -15 0 -
r (mm) 30 15 0 -
ETa (mm) 72 29 28 129
d (mm) 0 118 223 341
s (mm) 0 0 0 0
Irrigation (mm) 0 120 200 320
Table 1. Water balance of fibre hemp
ETo reference evapotranspiration (mm), ETm the maximum evapotranspiration irrigated (mm), ETd daily evapotranspiration (mm), Δ ±
difference in rainfall and ETm represents deficit or suficit after consuming or filling the reserve (r) of readily available water, ETa the actual
evapotranspiration rainfed (mm), d deficit of readily available water (mm), s suficit (mm)
Water used on evapotranspiration in irrigation
conditions (ETm) was 470 mm and 129 mm in non-
irrigated control (ETa) (Table 1). Similar values of water
used on hemp evapotranspiration of 535 mm, during
growing season in northwest Tasmania, were reported
by Lisson and Mendham (1998). Di Bari et al. (2004)
found out that 410-460 mm of water consumption was
needed for 28-38 t ha-1 of hemp green biomass
production in southern Italy. The highest
evapotranspiration rate in irrigation conditions (ETm)
was obtained for the period from appearance of male
flowers to the end of the season and amounted up to
251 mm, or 53.4% of total water used during the entire
growing season (Table 1). Merfield (1999) also reported
that hemp water demand is concentrated during the
rapid growth phase.
Evapotranspiration of hemp is highly dependent on
environmental requirements and growth stage. The
highest average value of 5.8 mm of daily water used on
evapotranspiration (ETd) was detected in the period of
appearance of male flowers to the end of the season,
while the average value for the entire growing season
was 4.3 mm (Table 1). Maximum daily
evapotranspiration value of 7.5 mm was detected on 10
July (Figure 2). These results are in accordance with the
results gained by Di Bari et al. (2004) for the maximum
values of hemp evapotranspiration of 6 mm in optimum
water regime.
Based on the obtained results it can be concluded
that irrigation has significantly affected the yield of
fresh stems, fresh leaves and flowers and plant height,
but not stem diameter and fibre content.
Water used on evapotranspiration in irrigation
conditions (ETm) was 470 mm while 129 mm in non-
irrigated control (ETa). The highest evapotranspiration
rate in irrigation conditions (ETm) was calculated for
the period of appearance of male flowers to and of the
season and amounted to 251 mm, or 53.4% of total
water used during entire growing season. The highest
average value of 5.8 mm of daily water used on
evapotranspiration (ETd) was detected in the period of
appearance of male flowers to and of the season while
the average value for the entire growing season was 4.3
mm.
These preliminary results could be used as a good
platform for hemp growers in the region, regarding
optimization of irrigation water use.
Bócsa, I., Karus, M. (1998). The cultivation of hemp. Botany, varieties,
cultivation and harvesting. Hemptech, Sebastopol, CA.
Bošnjak, Dj. (2001). The problems of drought in the Vojvodina
province and drought control measures. Zbornik radova Instituta za
ratarstvo i povrtarstvo Novi Sad, 35: 391-401.
Treatment Fresh stem yield
(g m-2)
Fresh leaves and
flowers (g m-2)
Stem diameter
(mm)
Plant height
(cm)
Fibre content
(%)
Irrigated 1950a 866a 5.83a 168.28a 32.10a
Non-irrigated 1316b 592b 5.81a 146.13b 31.95a
Table 2. Yield, morphological characteristics, and fibre content of hemp
Figure 2. Daily evapotranspiration of
fibre hemp
Cosentino, S.L., Riggi, E., Testa, G., Scordia, D., Copani, V. (2013):
Evaluation of European developed fibre hemp genotypes
(Cannabis sativa L.) in semi-arid Mediterranean environment. Ind.
Crops Prod., 50: 312-324.
Di Bari, V., Campi, P., Colucci, R., Mastrorilli, M. (2004). Potential
productivity of fibre hemp in southern Europe. Euphytica, 140: 25
32.
García-Tejero, I. F., Durán-Zuazo, V. H., Pérez-Álvarez, R.,
Hernández, A., Casano, S., Morón, M., Muriel-Fernández1, J. L.
(2014): Impact of Plant Density and Irrigation on Yield of Hemp
(Cannabis sativa L.) in a Mediterranean Semi-arid Environment. J.
Agr. Sci. Tech., 16: 887-895.
Hackett, C. (1991). Mobilizing environmental information about lesser
known plants: the vale of two neglected levels of description.
Agrofor. Syst., 14: 131-143.
Hargreaves, G. H., Allen, R. G. (2003). History and Evaluation of
Hargreaves Evapotranspiration Equation. Journal of Irrigation and
Drainage Engineering, 129 (1): 53.
Kišgeci, J. (1994). Praise to Hemp (in Serbian). Beograd, Novi Sad:
Nolit.
Lioveras, J., Santiveri, F., Gorchs, G. (2006). Hemp and Flax Biomass
and Fibre Production and Linseed Yield in Irrigated
Mediterranean Conditions. Journal of Industrial Hemp, 11 (1): 3-15.
Lisson, S., Mendham, N. (1998). Response of fibre hemp (Cannabis
sativa L.) to varying irrigation regimes. Journal of the International
Hemp Association, 5 (1): 9-15.
Merfield, C. (1999). Industrial hemp and its potential for New Zealand. A
report for the 1999 Kellogg Rural Leadership Course.
Van Dam, J. E. G. (1995). Potentials of hemp as an industrial fibre
crop. Proceedings of First Bioresource Hemp Symposium, nova-Institute,
Frankfurt, Germany, March 2-5: 405-422.
White, C.L., Griffin, P., McKnight, T. (1964). World Economic
Geography. Wadsworth Publishing Company, Belmont.
Sažetak: Eksperimentalna istraživanja o uticaju navodnjavanja kapanjem na prinos i evapotranspiraciju konoplje za
vlakno (Cannabis sativa L.) su obavljena na oglednom polju Instituta za ratarstvo i povrtarstvo iz Novog Sada u
Odeljenju za alternativne biljne vrste u Bačkom Petrovcu. Vreme zalivanja je određivano obračunom vodnog bilansa.
Dnevne vrednosti utroška vode na evapotranspiraciju biljaka (ETd) su obračunate korišćenjem referentne
evapotranspiracije (ETo) i koeficijenata useva (kc) čije su vrednosti 0,5, 0,9 i 1,1 za potperiode vegetacije konoplje od
setve do porasta 3-4 lista, od 3-4 lista do pojave muških cvetova i od pojave muških cvetova do žetve. Referentna
evapotranspiracija (ETo) računata je formulom Hargreaves-a. Zalivanje je obavljano kada su rezerve lakopristupačne
vode u sloju zemljišta dubine 0,4 m bile iskorišćene. Zalivna norma je na početku vegetacije iznosila 30 mm, a od
sredine vegetacije 40 mm. Navodnjavanjem je ukupno dodato 320 mm vode. Navodnjavanje je signifikantno uticalo
na prinos sveže stabljike, svežih listova i cvetova i visinu biljaka, ali ne i na dijametar stabla i sadržaj vlakna. Utrošak
vode na evapotranspiraciju biljaka u uslovima navodnjavanja (ETm) iznosio je 470 mm, a u uslovima bez
navodnjavanja (ETa) 129 mm. Preliminarni rezultati istraživanja mogu biti korišćeni kao dobra osnova za
proizvođače konoplje u regionu, u smislu racionalnog korišćenja vode za navodnjavanje.
Ključne reči: Cannabis, evapotranspiracija, konoplja, navodnjavanje
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Kenevir tarla koşullarında yetiştirildiği gibi, sera veya özel donanımlı büyüme odalarında topraklı veya top-raksız koşullarda da yetiştirilebilmektedir. Bitkilerin açık arazi koşullarında yetiştirilmesi iç mekâna göre daha kolaydır. Ancak her iki durumda da Uluslararası sözleşmeler ve ulusal yasalar gereği kenevir bitkisinin her türlü yetiştiricilik faaliyeti, izin gerektirmektedir (Bkz. Bölüm 18). Ülkemizde az miktarda da olsa tarla koşullarında yetiştiricilik yapılmakla beraber, sera şartlarında yetiştiricilik henüz bildirilmemiştir. Bununla beraber, Avrupa ülkelerinde özellikle de Hollanda' da eğlence amaçlı, İngiltere' de ise tıbbi amaçlı iç mekân yetiştiriciliği, yoğun olarak yapılmaktadır. Tıbbi, eğlence ya da endüstriyel amaçlı yetiştiricilikte bitkilerin üretilmesi, iyi tarım uygulamaları (sertifikalı çeşit kullanma; izlenebilir hasat ve kültürel uygulamalar) yapılmasını gerektirir. Bütün yetiştiricilik amaçları için literatürde bildirilen yoğun çalışmalar yapılmıştır. Her ne kadar bu kitabın içeriğinde konu edilmemişse de, üzerine onlarca kitap ve on binlerce araştırma makalesi yapılmış kenevir bitkisinden yasa dışı olarak üretilen esrar, genellikle kontamine olmuş ve içeriği kullanıcıların hayatını tehlikeye sokacak şe-kilde değişkenlik göstermektedir. Bu nedenle Bölüm 18' de de vurgulandığı gibi, yasadışı şekilde üretilen esrar, insan ya da çevre güvenliği açık bir şekilde göz ardı edilerek üretilmektedir. Bu kapsamda çok sayıda ülke-de esrar kullanımının yasallaştırılmasının sağlanması, yetiştiricilere yasal olarak meşru üretime girme fırsatı verirken, sektörün ise yüksek etik standartlarına sahip personel istihdamını zorunlu hale getirmektedir. Ülkemizde gıda ve özellikle pamuk gibi tekstil ham maddesi üretimi için tarımı yapılan birçok lif bitkisi türünün ham fiyatının düşük olması nedeniyle, bazı bitki türleri üretimi devlet tarafından desteklenmektedir. Pamuk gibi yoğun ekimi yapılan bitkilerin rotasyonu, nispeten kârlı olan veya rotasyonda agronomik olarak vazgeçilmez birkaç türle sınırlıdır. Rotasyon için bu az sayıda tür sayısı özellikle toprak patojenlerinin oluşmasıyla, hastalıkların görülme sıklığını arttırmak-la birlikte, verimi de düşürmektedir. Aynı zamanda biyositlerin, özellikle de toprak fumigantlarının daha fazla kullanılmasına yol açmaktadır. Tarla tarımının daha sürdürülebilir hale getirilmesi ve daha az kimyasal madde kullanması gerektiği genel olarak kabul edildiği için, bu durum endişe verici bir gelişmedir. Mevcut rotasyonlara eklenecek olan yeni bir ürünün tanımlanması ve geliştirilmesi, yukarıda açıklanan sorunların çözülmesine yardımcı olabilmesi muhtemeldir. Rotasyona girecek yeni türlerin; kârlı olması, geniş bir endüstri dalında kullanılması, iç pazarda olduğu gibi dış pazar için de üretilmesi ya da dış pazardan ithal ettiğimiz ürün talebini karşılaması, az miktarda ilaçlama gerektirmesi veya hiç kullanılmaması ve mevcut kültürü yapılan rotasyon türlerinde görülen hastalık oranını azaltmaya yardımcı olması gerekmektedir. Yaprak ve kaliksindeki tüylerinden 21. yüzyılın ilacı olacağı düşünülen psikoaktif olmayan kannabidiol ve kannabigevarin gibi kannabinoidler (Bkz. Bölüm 13); tohumlarından yemeklik yağ ve tedavi destekleyici be-sin maddeleri; gövdelerin dış dokularından lif, iç sert dokularından kağıt hamuru, otomotiv endüstrisi için ham madde ve binalara yalıtım malzemesi gibi binlerce ürünün üretimi için yapılacak kenevir yetiştiriciliğinde, yukarıda verilen sorunların çözümüne bir alternatif olarak yetiştirilebilir. Halihazırda kenevir tarımı üzerinde çok sayıda araştırma yapılmış ve yüksek verim ve kalite için uygun koşullar belirlenmiştir. Kenevir subtropik ve/veya kuru bölgelerde yetiştirilirken, gerçekte bu türün genotipleri lif ve yağlı tohum da dâhil olmak üzere, çok amaçlı olarak kullanıldığı zamandan beri, geleneksel üretim bölgelerinin dışındaki bölgelerde de lif için yetiştirilmektedir. Bu bölüm içeriğinde, iki alt bölüm halinde; (1) Lif kenevir tarımı ve (2) Tıbbi kenevir tarımı ile ilgili literatürde bildirilen teknik bilgi ve uygulamaları hakkındaki en temel bilgiler bir araya getirilmiştir.
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