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

Abstract

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.

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.