## 4 Discussion  
### Vegetative Plant Stage  
The lack of statistical differences observed in both the height and diameter of the _C. sativa_ plants is not surprising, given the earliness of the data collection date. Cannabis is known to be impacted by external factors, such as caliper size, regarding rooting success and vigor of vegetative cuttings ([PERSON] et al. [21]). These rooting challenges could readily deplete the available resources within the cuttings and result in a decrease in rooting vigor at transplant. This is primarily a result of P resources being involved in root growth and formation ([PERSON] et al. [21]). Additionally, high CBD cultivars do not have as vigorous a stem biomass production that some _C. sativa_ types exhibit, such as those grown for fiber ([PERSON] et al. [8]). Additionally, the lack of statistical differences observed after four weeks of vegetative growth could also indicate that the necessary biomass and nutrient accumulation was not yet impacting growth metrics. This can be seen in Table 1 where differences occurred in plant height and diameter regarding P concentrations, given the plants had longer to grow and the P limitations could be detected. After eight weeks of vegetative growth, differences were observed in the heights and diameters of _C sativa_ plants correlating to P concentration, showing that the lowest P rate resulted in both shorter and narrower plants. However, this difference was only observed between the lowest concentration and the remaining concentrations. This may indicate that a P concentration below 7.50 mg-L\({}^{-1}\) P may be close to the lower critical level of fertility for hemp during the vegetative stage. Further disparities in growth metrics (plant height and width) were observed at the later stages (pre-flowering and flowering); however, to maintain early vegetative growth, P fertility concentrations below 7.50 mg-L\({}^{-1}\) may be adequate. When we compare the leaf tissue values of the lower fertility levels of P, these values were similar to or within the values observed in [PERSON] and Mills (20) of 0.24-0.49% leaf tissue P. Additionally, the values observed in a survey of hemp plants grown in greenhouse conditions in North Carolina demonstrated that only the upper two P concentrations (22.50 and 30.0 mg-L\({}^{-1}\)) were within the survey values explored ([PERSON] et al. [7]). This adds credence to the idea that _C. sativa_ may need less P resources in the vegetative stage. This trend of lower P fertility needed by crops was observed in the work by [PERSON] et al. [10], who looked at six different species of floricultural crops. This work demonstrated that most species explored received adequate P fertility below the 15.0 mg-L\({}^{-1}\) P concentration in a greenhouse growth setting. Additionally, the lower P concentrations may not have produced divergent results, due to the role P plays in plant growth and development. For most plants, the optimal range of P concentration within the plant ranges from 0.3-0.5% plant matter ([PERSON] [22]). Within plants, P plays an important part in many enzymatic functions within plants by acting as a product, a substrate, or an activating or inhibitory component. Many of these enzymatic functions are directly related to metabolite and secondary metabolic pathways or have direct impacts on the energy available to these pathways ([PERSON] et al. [23]). Thus, the impacts of P deficiency would most likely be observed later in the _C. sativa_ lifecycle when the developing floral sinks start drawing upon the energy resources within the plant. This has been observed anecdotally in various _C. sativa_ operations and visits to grower operations by the authors. Plants which appear normal and healthy in the vegetative stage will produce deficiency symptoms shortly after the induction of short days and the production of floral materials. Furthermore, this was also observed in our experiment, that even the highest concentration of P fertility resulted in some visual symptoms of nutritive stress (Figure 4).