Characterization of Nutrient Disorders of Cannabis sativa

Abstract

Essential plant nutrients are needed at crop-specific concentrations to obtain optimum growth or yield. Plant tissue (foliar) analysis is the standard method for measuring those levels in crops. Symptoms of nutrient deficiency occur when those tissue concentrations fall to a level where growth or yield is negatively impacted and can serve as a visual diagnostic tool for growers and researchers. Both nutrient deficiency symptoms and their corresponding plant tissue concentrations have not been established for cannabis. To establish nutrient concentrations when deficiency or toxicity symptoms are expressed, Cannabis sativa ‘T1’ plants were grown in silica sand culture, and control plants received a complete modified Hoagland’s all-nitrate solution, whereas nutrient-deficient treatments were induced with a complete nutrient formula withholding a single nutrient. Toxicity treatments were induced by increasing the element tenfold higher than the complete nutrient formula. Plants were monitored daily and, once symptoms manifested, plant tissue analysis of all essential elements was performed by most recent mature leaf (MRML) tissue analysis, and descriptions and photographs of nutrient disorder symptomology were taken. Symptoms and progressions were tracked through initial, intermediate, and advanced stages. Information in this study can be used to diagnose nutrient disorders in Cannabis sativa.

A Review on the Current State of Knowledge of Growing Conditions, Agronomic Soil Health Practices and Utilities of Hemp in the United States

“…A study conducted by [16] also concluded that hemp growth response to fertilizer N was negligible in soils rich in N. Due to differences in environmental conditions and methodologies, the stem biomass per unit of N fertilization cannot be accurately determined from literature data and therefore warrants more investigation. A recently conducted study reported that N deficiency symptoms were observed in greenhouse-grown hemp for CBD when the N content in the leaf tissue analysis was 1.62% [68]. However, more research is needed to evaluate the effect of N application on the yield of seed and CBD hemp varieties under field conditions.…”

“…Hemp plants suffering from P deficiency show visual symptoms including stunted growth and development of reddish-purple color in the leaf due to anthocyanin pigment formation [72]. In a recent study, leaf tissue analysis of P was reported to be 0.09% for P deficient CBD hemp plants grown under greenhouse conditions [68].…”

“…Hemp is less responsive to potassium (K) compared to N and P fertilization, and very few experiments evaluating the effect of K on hemp have been conducted. One of the studies reported that K did not significantly affect hemp biomass and seed yield [68]. K is a macronutrient and is required in substantial quantities by hemp.…”

“…K fertilizer trials suggested that hemp should receive 175 kg K ha −1 [74]. A recent study conducted on CBD hemp under greenhouse conditions reported the K content in leaf tissue to be 0.41% for K deficient hemp plants [68]. However, the effect of K fertilization on the seed and CBD yields in hemp varieties in the field have not been reported to our knowledge.…”

“…A study conducted in Russia on peat-humus soils have shown that the yield and quality of fiber and seed hemp fertilized with sufficient P and K could be increased by supplemental application of 1 kg of B (as boric acid (H 3 BO 3 )), 1 kg of Cu (as copper sulfate (CuSO 4 )), and 10 kg of Mn (as manganese sulfate (MnSO 4 )) ha −1 [76]. Leaf tissue analysis of CBD hemp during deficiency symptomology for a wide range of nutrients including Mg, Sulfur (S), B, Cu, Mn, molybdenum (Mo), and zinc (Zn) were reported in a study conducted by [68]. This study also suggested that with the exception of N, K, B, and Cu, other nutrient deficiencies did not significantly decrease the CBD hemp yield.…”