The cannabis industry is made up of different segments, because of the many different products cannabis can be applied on. And indeed, depending on the product, a specific cannabis plant can contain more of a certain compound than another. Based on this distinction, regulators differentiated between high-THC cannabis, and low-THC/high-CBD cannabis, also known as hemp. Because it is important to maximize the production of specific compounds, growers have to be perfectly in tune and knowledgeable with the plant they are growing. Unfortunately, because of the illicit status that the cannabis plant had over the past decades, it was extremely difficult for universities and researchers to further study and understand the complexity of the cannabis plant.
Yet, as the industry was regulated, the research has been slowly catching up, thus allowing the whole cannabis sector to better understand how to grow the best crop. In a paper published in Agronomy, titled “Effects of Drought and Heat on Photosynthetic Performance, Water Use and Yield of Two Selected Fiber Hemp Cultivars at a Poor-Soil Site in Brandenburg (Germany),” by Herppich, Gusovius, Flemming, and Drastig, the authors states that, in recent years, crops in Northern Central-Europe have experienced a combination of drought and heat. Thus, studies have been done to better understand the effect on the photosynthesis and stomatal conductance. The cultivars used for the experiment were ‘Ivory’ and ‘Santhica 27’, and the essential actual physiological, such as rates of photosynthesis and transpiration, and the yield performance were evaluated in highly limited soil water supply and extreme environmental conditions. The goal of the study was to provide some insight in the usability of said genetics in harsh productive conditions.
The results of the experiment showed that ‘Ivory’ developed higher rates of CO2 and a large leaf area in mid-season, while ‘Santhica 27’ used lower CO2 uptake at lower leaf area. This resulted in a higher yield compared to ‘Ivory’, “nearly twice as much”, the paper reads. Yet, ‘Ivory’ showed a higher intrinsic water use efficiency as a consequence of the higher stomatal limitations.
The authors finally conclude that both of the hemp genetics utilized in the study can be grown without a consistent irrigation in northern Central Europe, even when hot and dry climate conditions are present, without ultimately affecting the yield and quality. At the same time, they state that “low basic irrigation during the phase of seed germination is advantageous to guarantee even sprouting and seedling establishment.”