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Member Since 10 Sep 2017
Offline Last Active Aug 08 2018 09:18 AM

Posts I've Made

In Topic: Plant stress and pepper heat -- recent research

18 July 2018 - 04:21 PM

I don't have time just yet to write a full reply. But obviously this is a complex area, and I've simplified the presentation for a general audience, so perhaps omitted some of the more nuanced results/discussion from the paper. 


This has been discussed alot - and even hotly debated on this forum.  I tend to disregard this study for a few reasons. 


Read it before you dismiss it?



First and foremost, how many plants were utilized in each sample?  It appears to be one per variety.


Three replicates per plant per treatment. So 42 plants total. 


If that's true, it wouldn't even get us out of the territory of statistical error.  There needs to be a much wider sampling, for this to be taken seriously.  Or, if it is a larger sampling, that should be quantified.


Yes, larger sample sizes are ideal as they allow for small effect sizes to be detected. But small samples can still detect statistically significant effects that are large. 


The argument can be made that the study might have been underpowered to detect smaller increases in capsaciacin at the 2-day mark, but with an alpha set to 0.05, the type 1 error rate is controlled. (i.e. false positives)  


Not only that, there is a clear dose-dependent effect here. 



Second point...  and of the most importance - there are OTHER studies which suggest that the greatest deviation in capsaicin levels, occurs in those varieties with a much lower capsaicin content. (or lower Scoville rating, to keep it simple)  A study at the University of New Mexico found that drought stress was most effective in lower heat level varieties - like any NuMex anuum, jalapeno, serrano, etc.  That contradicts this study.  


From the discussion section


The previous studies that worked with various types in fruit size and pungency of hot pepper revealed that the small-fruited cultivars are less affected by environment compared with the medium and large-fruited cultivars (Gurung et al., 2012Gurung et al., 2011Phimchan et al., 2012Phimchan et al., 2014).



And from Primchan et al., 2012 


However, in our study, the significant increases in capsaicinoids were observed only for the low and medium pungent cultivars but not for the high pungent cultivars. These results might be explained by the fact that a genotype and genotype–environment interaction affected capsaicinoid content (Zewdie and Bosland, 2000), in which the genotype effect was larger than the environmental effect (Gurung et al., 2011b; Zewdie and Bosland, 2000). In addition, Gurung et al. (2012) found high stability of cultivars with high pungency, whereas the lower pungent cultivars were very sensitive to environment. From our results, it is notable that the fruits of the high pungent cultivars are smaller than the other cultivars used, and this might indicate that the capsaicinoids in the small fruit of the high pungent cultivars are less affected by drought stress than those of the big fruit with low and medium pungency.



I might also add the Bosland, head honcho at UNM, is a co-author on these papers. 



And I know that the NM study was quite a bit more comprehensive, because it involved money being invested for the direct benefit of commercial growers. (who wouldn't want to make a hotter pepper, and use less water - reduce costs, maintain desirability of product, right?)


This reasoning appeals to common sense but is a bit wishy washy. 


You could make a similar argument here, this study is for the benefit of the pharmaceutical industry, who want to extract the optimal amount of capscaicinoids out of their harvests are possible. 



In Topic: DIY Mini Greenhouse to ripen the last wave of pods

18 July 2018 - 03:53 AM

That's awesome!  Looks like the Aji had a bunch of pods on it in the pic above from week ago.  Are they getting close?  Any movement on the t-scorps?


Also curious if the pod is firm/crisp.  It looks solid, but I have seen some cold weather ripenings where the pods ended up soft when they took too long.  I remember that happening with an Aji Limon in particular, which was a major bummer because it was really loaded down.


Great work man!


For the Aji about a 1/3 of the pods are ripe, the others are starting to turn too. Interestingly, the pods were actually still crisp! On the other hand, my shishito has been ripening for probably months now, and like you mentioned, it's actually quite wrinkled and soft, despite being mostly unripe. I'm really just interested in the seeds at this point. 


The t-scrops are still moving pretty slowly... I can't really notice much of a change since I took the photo. It's still alive though, so there's that. 

In Topic: DIY Mini Greenhouse to ripen the last wave of pods

17 July 2018 - 08:21 AM

Success! Mid winter outdoor ripening!



In Topic: Limited heat mat real estate -- cardboard dividers for cups?

11 July 2018 - 10:42 AM

Or just skip the heatmat altogether, for where you don't have the room...  They'll sprout. ;)


Certainly an option too. But it might be a slow process no? The heating isn't working at the moment, so it's about 15*C/60F indoors

In Topic: I think my pepper plants are doing well!

11 July 2018 - 10:38 AM

They're huge! Congrats


I'd probably just let them be, for the same reasons.