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About the seedlings

A few years ago I started growing Phyllostachys arcana ‘Luteosulcata’ seeds and noticed 3 seedlings had a bit different leaves which could be a sign of possible variegation. As time went by, it became apparent that there were 3 seedlings that had shown different levels of variegation. All of them started more variegated in the spring and then, with passing growing season, got greener. They were much greener in the autumn and winter than they appeared in the spring, especially the third seedling, which “reverted” to almost completely green color by then.

The first seedling remains most variegated and has been struggling to grow much larger in its raised bed where resources are extremely limited and has shown drought issues during hot summer months. The first seedling doesn’t have culms large enough, so I’ll leave it out for now. Stems of the first seedling are pale green and they turn dirty yellow with time. There are green streaks on them, but due to small diameter of the culms it produces, I think it’s too early to tell how they look. The second in line based on level of variegation is the second seedling. It appears completely yellow in the spring, like its older brother, but gets darker faster and ends up more green in autumn. Due to the fact it ends up with higher chlorophyll levels, it grows faster and in much more aggressive manner.

So what about the culms

The difference in culm coloration became apparent quite early. Leaves appear almost uniformly colored – lime green, then the pigmentation settles, darker green striping forms and the paler green color turns yellow. It seems as the chlorophyll migrates into green stripes, leaving parts almost completely without green pigment. The same thing seems to happens in culms, which only show slightly different coloration at first and gradually change, so that the coloration becomes evident. As the culms mature, the coloration gets very obvious. As I already mentioned, all three variegated seedlings also have variegated culms. Pigmentation patterns couldn’t be more different though.

The second seedling’s culm coloration

Phyllostachys arcana ‘Luteosulcata’, the mother and father of these seedlings has culms that are dark green with a bright yellow sulcus. My second seedling ended up almost as an inverted version of its parent. Lower internodes are mostly dark green with occasional striping which is not as evident as with 3rd seedling. Up the stem, things start getting more interesting. Culm starts getting more yellow, top of the bamboo gets practically completely yellow. Sulcus, however, usually gets green. And not only culms, some branches that also develop sulcus also get their green colored groove. It is not dark green, and the yellow culm color is not as bright as it could be, but the coloration is there and with time it gets more pronounced as the culms mature.

The third seedling’s culm coloration

Despite being much, much less variegated when it comes to leaf pigmentation, the third seedling develops culms that are strongly variegated. The type of variegation is similar to other seedlings – the bottom of the culm is practically green with darker green stripes that are not nearly as evident as the stripes up the stem. As you climb up the culm, color also turns more yellow, this time, sulcus doesn’t really count – variegation is different. Green and yellow striping on this seedling is randomly scattered all around culm’s surface. As with previous seedling, variegation becomes more evident with time.

Measuring growth

I was always impressed by how fast and how tall bamboo can grow. Sometimes you can almost see it grow and if you check it twice in the same day, the difference can be quite evident. To get a better picture about the growth speed of my Moso seedling, I decided to monitor its growth. I’ll write down the measurments and any other gathered information in this post.

…it grows – fast!

It was quite easy to check the length of the shoot at first but as soon as it overgrew me, things got complicated. I could have used a ladder and make a couple more measurements, but I knew soon it wouldn’t be enough, so I started using a taller bamboo pole to measure growing shoot. That solution worked sufficiently, but at one point, right before branching, bamboo started bending which made it nearly impossible to check its height. That was when I stopped measuring.

Adding weather into equation

When I got all the measurement results, I decided to check the meteorological data, calculate mean daily temperature (which includes both, day and night temperatures) and precipitation. The main idea was if I can find any correlation between weather and growth speed.

Mean daily temperature ranged from around 10°C to a bit above 18°C. The lowest temperature was detected on May 12th. On that day, and the morning of May 13th, temperature dropped to around 5°C. Strong cold front brought a decent amount of rain as well, which might have cooled down the soil a bit and considerably slowed down the growth, which almost stopped the following day (May 13. 2020 ).

Conclusion

At first relatively small shoot start to accelerate its growth progressively, when a bunch of internodes start to elongate simultaneously. In optimal conditions, graph would likely have a nice curve with its peak right before branching out and then rapid decline in growth speed. In time of drought, beneficial factor would likely be precipitation, in this case, it was the temperature that regulated the speed of bamboo culm elongation. If we consider that height measure gives us information about growth during previous day, It becomes clear that one day lag after a drastic cooldown or warm-up is logical. Exactly that happened on May 12th. I will get some more information this year to confirm the temperature / growth speed correlation.