It would be quite unbecoming of me to show step-fatherly treatment to our yellow capsicum – while I spoke so effusively of our red capsicum in an earlier post – which, though a wee bit late in yielding fruit, has contributed in no lesser way to, well, my cultivation of knowledge.
This round of experimentation was an attempt at cross-pollination between the red and yellow cultivars to check if it was possible to have fruit of a mix of colours on the same plant. Towards this end, I selected six flower buds each on the two plants which looked destined to bloom more or less around the same time. These were isolated and covered throughout to prevent pollination by any external agent. My next step, logically, was to remove the anther lobes from the flowers as soon as they bloomed; which to my chagrin I found easier said than done – the flowers bloomed at random times of the day and I could not always be present with forceps drawn; also, many of the flowers were on the branches reaching outside my window box grill and facing the sun. Thus, I had to give in to the probability of self-pollination, though I still managed to emasculate four of the twelve flowers.
Then I went about collecting pollen from each flower as the anther lobes dehisced, transferring it to the stigma of the target flower using fresh and sterile forceps for each transfer. Thus in a matter of days I had six flowers each on the two plants – the reds dusted with pollen from the yellows and vice versa (of course baring stigma of those eight flowers which had their own pollen too). Done and dusted (pollen I mean), all I could do now was wait!
Of the six flowers on each plant, five of the red cultivar and four of the yellow cultivar developed into fruit. Five weeks later as the nine green fruits reached maturity, a breakout of hues of red and yellow gave me an initial glimpse of the results. Soon, the five fruits on the red cultivar were all blushing a familiar red while the four fruits on the yellow cultivar were all a sunny side up yellow!
There could have been two possibilities here – either all nine capsicum were borne out of self-pollination, or else cross-pollination made no difference to the end result. Though likelihood of the former could very much be a distinct possibility, referencing of published studies gave me some pointers towards the latter too.
The formation of colours is an intricate mechanism of genetic expression and enzymatic action. It is known that capsanthin and capsorubin are the key carotenoids that cause the typical red colour during ripening process of red capsicum. These pigments in turn are controlled by the capsanthin-capsorubin synthase (Ccs) gene. In yellow capsicum cultivars this gene has a mutation which leads to its suppression and thus dominance of yellow pigments resulting in the fruit ripening to a yellow. One probability I draw from my experiment is that the Ccs gene could be present on a female dominant chromosome (in ovules) and hence colour of the fruit would be independent of the genetic makeup of the male chromosomes (in pollen). Hence, as far as colour goes, self or cross-pollination would be immaterial.
My experiment was neither scientifically fool-proof, nor the study sample size adequate to be conclusive either way. It was simply suggestive of a direction to take and gave me enough fodder for thought. However, one positive takeaway from this trial run of growing red and yellow capsicum was that it turned out to be a myth buster. Yes, the red and yellow capsicum plant are distinct cultivars and, no, there is no progression of the colour of fruit from green to yellow to red as it ripens as some websites had me believe. I can now state with authority that fruits of both the red and yellow varieties start off green till they reach maturity at which point, depending on the cultivar, they ripen into either red or yellow. And that is one tiny monkey off my back!
– Narendra Nayak © 2022