cannetix Inc
Well-Known Member
The Numerous Benefits of ‘Selective Defoliation’ and Why I Trim
Disclaimer: I understand that this topic is controversial and that many threads on the topic already exist. This thread is intended only to provide my own personal view on the topic based on my own, personal research and experience.
‘Selective defoliation’, or as some growers refer to it in the cannabis community; Lollipopping is a topic that sees a great deal of debate. While many experienced growers swear by the technique, many others are adamant that it should never be done. To understand why selective defoliation, when done properly, can improve health, vigor, yield, etc. you must first understand some basics about plant physiology. Plants are autotrophs that synthesize their own food through photosynthesis, a process that occurs predominantly in the leaves. Cells high photosynthetic pigments – chlorophylls – absorb light and catalyze (“initiate”) a reaction between Water (H2O) and Carbon Dioxide (CO2). The result of this reaction is the simple carbohydrate or monosaccharide known as Glucose. Plants can then either use Glucose in the process of cellular respiration, burning it with oxygen to create energy. Alternatively, plants can use these monosaccharides as building blocks for more complex polysaccharides, such as Cellulose, that make up their structure and tissues.
Although the entire plant appears uniformly green, it is important to realize that only some cells actually contain Chloroplast (The chlorophyll-containing organelles). If you look at plant tissue under a microscope, the majority of its cells will actually appear nearly completely colorless and translucent, with pockets of vibrant green appearing (mostly) surrounding pores on the leaves, known as Stomata. The argument against selective defoliation is a simple one; the leaves are the “powerhouse” of the plant and for every leave that is removed the plants' growth will be stunted.
This, however, may not be entirely true. As leaves age, the density of chloroplast containing cells decreases significantly, as does the concentration of various phenols (Apigenin, Resveratrol, etc.). Due to the fact that a plant can only synthesize so many molecules of chlorophyll, and so many of these important phenols, selectively removing old-growth can, both in theory and as demonstrated by real-world study, improve the photosynthetic properties of the remaining, young growth. We see this same phenomenon occurring on a larger scale in forest ecosystems, where the clearing of old-growth trees causes undergrowth to flourish. Young undergrowth, which grows quickly, actually sequesters significantly higher levels of Carbon compared to massive old growth trees, many of which are done growing and have begun the slow process of rotting out from the inside. The following is an excerpt from a study done in 'Frontiers of Plant Science', a rigorously peer-reviewed journal that is the #1 most cited and the leader in the field of agricultural sciences. The journal is available here.
"In many plant species, partial defoliation leads to increased photosynthetic rate in the remaining plant tissues (Strauss and Agrawal, 1999; Retuerto et al., 2004), suggesting that compensatory photosynthesis is a common physiological response to leaf damage (Tiffin, 2000). However, increased photosynthetic activity is not a universal response to herbivory and does not always drive compensatory growth, possibly due to resource diversion into resistance traits (Tiffin, 2000). Herbivore identity can determine whether changes in photosynthetic rate and growth occur: for example, compensatory photosynthesis is induced by several insect herbivores of soybean and drybean, but not by Mexican bean beetle (Peterson et al., 1998). By contrast, aphid feeding on the perennial crop red raspberry frequently stimulates plant growth and influences nitrogen physiology (Johnson et al., 2012), which could reflect tolerance to aphid herbivory through increased plant vigor (Karley et al., 2016). Similarly in sugarcane, clonal variation in tolerance to root-feeding whitegrub correlated with increased plant vigor (Allsop and Cox, 2002). Plant vigor can provide tolerance to herbivory in a range of plant species (Price, 1991); higher abundance and fitness of many insect herbivore groups on vigorous host plants (Cornelissen et al., 2008) could reflect increased ability of vigorous plants to tolerate attack. Although plant vigor is likely to be controlled by multiple loci, quantitative trait loci (QTL) studies have identified genetic markers for vigor (e.g., root and shoot vigor in raspberry: Graham et al., 2011, 2014) that could be deployed in crop breeding.”
Disclaimer: I understand that this topic is controversial and that many threads on the topic already exist. This thread is intended only to provide my own personal view on the topic based on my own, personal research and experience.
‘Selective defoliation’, or as some growers refer to it in the cannabis community; Lollipopping is a topic that sees a great deal of debate. While many experienced growers swear by the technique, many others are adamant that it should never be done. To understand why selective defoliation, when done properly, can improve health, vigor, yield, etc. you must first understand some basics about plant physiology. Plants are autotrophs that synthesize their own food through photosynthesis, a process that occurs predominantly in the leaves. Cells high photosynthetic pigments – chlorophylls – absorb light and catalyze (“initiate”) a reaction between Water (H2O) and Carbon Dioxide (CO2). The result of this reaction is the simple carbohydrate or monosaccharide known as Glucose. Plants can then either use Glucose in the process of cellular respiration, burning it with oxygen to create energy. Alternatively, plants can use these monosaccharides as building blocks for more complex polysaccharides, such as Cellulose, that make up their structure and tissues.
Although the entire plant appears uniformly green, it is important to realize that only some cells actually contain Chloroplast (The chlorophyll-containing organelles). If you look at plant tissue under a microscope, the majority of its cells will actually appear nearly completely colorless and translucent, with pockets of vibrant green appearing (mostly) surrounding pores on the leaves, known as Stomata. The argument against selective defoliation is a simple one; the leaves are the “powerhouse” of the plant and for every leave that is removed the plants' growth will be stunted.
This, however, may not be entirely true. As leaves age, the density of chloroplast containing cells decreases significantly, as does the concentration of various phenols (Apigenin, Resveratrol, etc.). Due to the fact that a plant can only synthesize so many molecules of chlorophyll, and so many of these important phenols, selectively removing old-growth can, both in theory and as demonstrated by real-world study, improve the photosynthetic properties of the remaining, young growth. We see this same phenomenon occurring on a larger scale in forest ecosystems, where the clearing of old-growth trees causes undergrowth to flourish. Young undergrowth, which grows quickly, actually sequesters significantly higher levels of Carbon compared to massive old growth trees, many of which are done growing and have begun the slow process of rotting out from the inside. The following is an excerpt from a study done in 'Frontiers of Plant Science', a rigorously peer-reviewed journal that is the #1 most cited and the leader in the field of agricultural sciences. The journal is available here.
"In many plant species, partial defoliation leads to increased photosynthetic rate in the remaining plant tissues (Strauss and Agrawal, 1999; Retuerto et al., 2004), suggesting that compensatory photosynthesis is a common physiological response to leaf damage (Tiffin, 2000). However, increased photosynthetic activity is not a universal response to herbivory and does not always drive compensatory growth, possibly due to resource diversion into resistance traits (Tiffin, 2000). Herbivore identity can determine whether changes in photosynthetic rate and growth occur: for example, compensatory photosynthesis is induced by several insect herbivores of soybean and drybean, but not by Mexican bean beetle (Peterson et al., 1998). By contrast, aphid feeding on the perennial crop red raspberry frequently stimulates plant growth and influences nitrogen physiology (Johnson et al., 2012), which could reflect tolerance to aphid herbivory through increased plant vigor (Karley et al., 2016). Similarly in sugarcane, clonal variation in tolerance to root-feeding whitegrub correlated with increased plant vigor (Allsop and Cox, 2002). Plant vigor can provide tolerance to herbivory in a range of plant species (Price, 1991); higher abundance and fitness of many insect herbivore groups on vigorous host plants (Cornelissen et al., 2008) could reflect increased ability of vigorous plants to tolerate attack. Although plant vigor is likely to be controlled by multiple loci, quantitative trait loci (QTL) studies have identified genetic markers for vigor (e.g., root and shoot vigor in raspberry: Graham et al., 2011, 2014) that could be deployed in crop breeding.”
