RELATIONSHIP BETWEEN LEAF NUTRIENT CONCENTRATION AND THE YIELD OF FIBRE HEMP (CANNABIS SATIVA L.) PUBLISHEDIldikó IVÁNYI
This study was conducted to determine the optimum time for plant analysis, which can provide useful indications of nutrient deficiencies in plants, and to establish limit values for nutrient supplies to fibre hemp (Cannabis sativa L.). The effect of nutrient supplies on the nutritional status of fibre hemp was estimated by leaf analysis in a long-term field fertilisation experiment at four NPK levels on chernozem meadow soil in Szarvas, Hungary in 1999 (good water supplies) and 2003 (dry). The optimum time for the diagnostic analysis of fibre hemp was found to be late May or early June, when plants in the 5–7-leaf stage are 70–100 cm in height, with a biomass of 2–5 t ha –1 dry matter, depending on water and nutrient supplies, variety and production condition. Nutrient supplies to hemp can be considered satisfactory if plant analysis reveals 5–6 % N, 0.5–0.6 % P and 2.7–3.3 % K in the youngest fully developed leaves in late May. A stem yield (10 % moisture content) of 12–17 t ha –1 was achieved when rainfall supplies were adequate (1999), while in the dry year (2003) the lower nutrient concentrations in the uppermost leaves, indicating nutrient deficiency, resulted in a maximum stem yield of only 6–8 t ha –1 . The low, satisfactory and high values for the concentrations of N, P, K, Ca, Mg, Fe, Mn, Zn and Cu reported in the paper could be used to elaborate a fertiliser recommendation system for hemp.
fibre hemp, soil analysis, plant analysis, nutrient deficiencies, nutrient limit values, dry matter yield