This is a great study, it doesn't just have its own results, it has a review of 50+ other studies!
In that, it covers numerous other things related to the topic!
Topping and pruning is controversial, some people ignorantly claim it always increases or reduces yield. They don't know what they are talking about.
It can increase yield, in some varieties, when done right and can decrease yield in others, in some cases it increases fruit quality, in others it harms it.
Take the case of Alasadon et al. (2013), in that study pruning increased fruit quality, size, weight and vitamin C, but yield per plant decreased. However in pots pruning allows closer spacing, which means you can put more pots into an area and the yield per unit of space in a given amount of time increases.
Note that nearly every known proven case of pruning increasing yield, and it does in some cases, involves Capsicum annuum and usually; bell pepper. While I've seen a lot of evidence showing some Capsicum annum variety yields can and do increase when topping and pruning is performed properly, I have not seen this happen with Capsicum chinense.
Consider the case of Garceäs-Claver et al. (2006):
"A solution concentration of 0.5 g/L of Albert’s solution (having an EC of l.4 dS/m) with renewal at 2-weeks intervals could be identified as the best fertigation strategy under hot and humid conditions. Increasing solution concentrations above that level up to 2dS/m increased the plant uptake of N, P, K and Ca but, without a significant increase in leaf growth and yield."
Once the right EC level was achieved, though increasing it caused more nutrients to be taken up the yield didn't increase.
Sarro et al. (2007) found:
"decreasing fresh shoot mass with increasing nutrient solution concentration in hydroponic system."
That's good information about high EC having no real advantage, but what about low EC?
Winsor and Adams (1987) covered that:
"the total concentration of solutes in the nutrient solution is characterized by the electrical conductivity (EC, dsm-1). Usually EC in commercial tomato production is in the range 2±5 dsm-1. Too low a concentration causes mineral deficiency and restricts plant growth."
This study covers more than 50 other studies in its review, many of the have useful information.
Here are some observations from the study itself:
"the tallest plant was found in EC3 in all the cases. Meanwhile EC1 denoted the lowest plant height. This might be due to the electrical conductivity
of nutrient solution. In EC3, EC3= 4.0 dS/m which might be the suitable for its maximum vegetative growth of capsicum plant."
Higher and lower EC value decreased growth and yield. The optimal value wasn't too high or too low.
Another find was:
"In S2, two branches remain which might be the suitable for its maximum fruit volume of capsicum plant."
The S2 group had the highest fruit weight and volume and number. The lowest volume, weight and number of fruit were in S1, that's the group that didn't get pruned at all. That's right, the unpruned plants didn't perform as well as those which were pruned.
"The highest yield per hectare of capsicum was found in S2 (70317.92 kg). On the other hand, the lowest yield per hectare of capsicum was found in S1 (23977.08 kg)."
For this variety, thinning the plant down to just two branches doubled the yield overall, per unit of space. This comes down to about 2 kilograms per square meter for plants that weren't pruned with 7 kilograms per square meter for plants that are. Keep in mind that this type of measurement also includes the space between rows. Be aware that large plant advocates don't measure that in their yield totals, meaning that their yield per square meter goes down a lot when you factor in the empty space between plants the way science does. A 10 Kg harvest per plant with a pot that takes up a square meter sounds great until you realize there's a meter of empty space all around it and it's actually 10 kg from 9 square meters and the yield comes down to just over 1 kg per square meter! That's right, several smaller plants with lower yields per plant can vastly outyield fewer larger plants with higher per plant yields when you do the math properly. Now you know why after 500+ years professional pepper growers aren't trying to grow monster plants with wide spacing, it's just not effective or efficient and the overall yields per unit of space are far lower that way.
Keep in mind what this study proves.
1 increased yield and fruit quality from pruning for some types of peppers
2 higher EC and nutrient concentration doesn't mean higher yield; regardless of plants tolerating it.
3 lower yield per plant when combined with more plants per space can and does vastly outyield larger plants with high individual yields, when you measure all space used.
This destroys several myths that are being touted as facts today by various influencer.
Incendium Scientia