Pruning Tithonia diversifolia for optimal biomass

[Tim_Motis]

How does pruning height and frequency affect biomass production of Tithonia diversifolia? This question was studied in Ghana by Partey (2010). He was interested in it from the standpoint of prunings for soil improvement. The idea is to transfer nutrient-rich biomass to the soil by leaving prunings on the ground or transferring them to growing spaces. As shown in previous research by ECHO, Tithonia diversifolia (also known as Mexican sunflower) is rich in nitrogen, phosphorus, and potassium, with levels comparable to moringa (Moringa oleifera) and lablab (Lablab purpureus) (EDN 134). ECHO’s North America Regional Impact Center staff in Florida also use it for making bioliquid fertilizer (EDN 157).

Partey (2010) worked with 5-year-old Tithonia plants spaced 1 m X 1 m apart. The plants were 2.3 m tall at the beginning of the experiment. He studied three cutting heights (25, 50, and 100 cm) and three pruning frequencies (2, 4, and 8 weeks between pruning events). Dry matter production (stems and leaves) was recorded each time the plants were pruned.

Here are some findings:
• Frequent pruning (e.g., 2 week intervals) resulted in high (≈ 90%) mortality of Tithonia plants. This was attributed, at least in part, to depletion of carbohydrate reserves with frequent foliage loss.
• Longer pruning intervals improved biomass production.
• Biomass production was highest with a cutting height of 50 cm.

Cutting plants to a height of 50 cm at 2-month intervals resulted in dry matter yield as high as 7.2 metric tonnes per hectare. It was recognized that results could vary depending on the age of the plants and location. If you are using Tithonia as a green manure, this data may be helpful to you.

Be aware that Tithonia diverifolia is considered invasive in many countries. Allelopathy may have a role in giving it a competitive advantage over native plants. Introducing it to new areas should be done with caution. Cutting Tithonia biomass as green manure could be a way of managing existing plants for obtaining green manure. It has been used as a green manure for crops such as rice and maize.

Here are a few photos of Tithonia growing at ECHO in Florida. The first one shows regrowth of green stem tissue after pruning:

Reference
Partey, S.T. 2011. Effect of pruning frequency and pruning height on the biomass production of Tithonia diversifolia (Hemsl). Agroforestry Systems 83(2):181-187. DOI 10.1007/s10457-010-9367-y.

[AFHGlen]

Tim, that is very useful. Thanks for sharing.

One question. Is there evidence that Tithonia has allelopathy properties?

[Tim_Motis]

Yes, that brings up a good point. Tithonia diversolia is considered invasive in a lot of places, and allelopathy has been posited in the literature as means by which it competes with native plants. I’ve added a word of caution to the original post about introducing it to new areas. Despite reports of allelopathy, there are also reports of increased yields with Tithonia green manure on crops like rice and maize. To my knowledge we haven’t observed negative effects of Tithonia used as bioliquid fertilizer. Others may have additional perspsective.

[AFHGlen]

My reason for asking is we are planning to begin planting it with our plantains as a chop and drop cover crop to provide nutrition for the plantains, but would be reluctant to do that if the allelopathic characteristics of it would hinder the growth of the plantains. What is your opinion of growing it adjacent/with plantains?

[Tim_Motis]

While I can’t speak from personal experience as far as trying this myself, I’ll share a few thoughts based on what I’ve seen here at ECHO in Florida and some findings from the literature.

First, we have T. diversifolia growing in close proximity to bananas in our syntropic ag planting/demo. The tithonia plants in the picture below were pruned, so they have been growing with the bananas for a while. While it’s not possible in this plot to compare banana growth with and without T. diversifolia it at least shows that bananas are growing quite well.

Looking at the scientific literature, I didn’t come across anything that addressed allelopathic activity of T. diversifolia against bananas, but found a couple that showed potential benefits of T. diversifolia. I’ll paste a summary statement with reference info below:

Liquid extracts of T. diversifolia improved resistance of banana seedlings to black Sigatoka disease

Tatsegouock, R.N., C.A. Ewané, A. Meshuneke, and T. Boudjeko. 2020. Plantain Bananas PIF Seedlings Treatment with Liquid Extracts of Tithonia diversifolia Induces Resistance to Black Sigatoka Disease. American Journal of Plant Sciences, 11:653-671. https://www.scirp.org/journal/paperinformation?paperid=100268

A six-month T. diversifolia fallow reduced two species of parasitic nematodes, enhancing the productivity of a subsequent planting of bananas

Gnonhouri, P.G., A. Zézé, A. Adiko, and K. Kobenan. 2019. Tithonia diversifolia crop rotation: an efficient cultural practice for burrowing (Radopholus similis) and root-lesion (Pratylenchus coffeae) nematodes in banana orchards in Côte D’ivoire. International Journal of Phytopathology 8(3):101-109. https://esciencepress.net/journals/index.php/phytopath/article/view/3029 (on this page, find a full-text version of the paper by navigating to “Issue” and then to Year 2019 under Vol 8 No. 3; clicking on that will take you to a page where the title of this paper appears along with a PDF download link).

Though not related directly to bananas/plantains, I found a review paper by Opala 2020 that gives some reasons why T. diversifolia as a green manure has not been as widely adopted by farmers as perhaps anticipated. It talks about the labor associated with cutting and transferring biomass. I can see where this could be minimized depending on your planting/row configuration. It also discusses variable nutrient composition and perspectives on whether or not it actually makes phosphorus more available to plants and increases soil organic matter (rapid decomposition is said to reduce its ability to build soil organic matter). In the section on “Response of crops to tithonia biomass,” however, it is encouraging to read that studies are mostly in agreement that crops respond favorably to T. diversifolia as green manure. It mentions a recommended rate of 5 t/ha of dry matter.

Hopefully, this info helps in your decision-making. Always informative to hear of first-hand experiences.

Tim

[Marie_Nsobih]

I love the subject. In my research farmers confirmed that tithonia improve soil fertility but however they prefer using it in compost production. Tithonia is very competitive amd inventive and farmers will remove them completely from the farm before and even after planting

[Tim_Motis]

Thank you Marie. It is encouraging to hear that farmers are using it in compost. It was interesting to note from the research by Partey (2010) that frequent pruning (2 week intervals) resulted in 90% mortality of tithonia plants. That could be useful info from the standpoint of making use of the prunings for soil improvement while keeping tithonia in check.

[Dan_Janzen]

I know for trees a pyramidal pruning system is likely to work best, like a Christmas tree is pruned. That is something to try. That allows all parts of the tree to get optimal light for photosynthesis and in the tropics this is very helpful since there is generally a lot of light, particularly in the dry season. It may be that the tree or plant will do better with a taller pyramidal shape in the dry season and a shorter pyramidal shape in the cloudy rainy season if it is grown as an annual. In addition, it may be better to have a steeper slope in the design on the west (or southwest or northwest depending on the latitude) where afternoon sun is more stressful and a shallower slope on the east side where morning sun is less stressful. The plants/trees should be spaced at an appropriate distance so that when a pyramidal form is done through sheering as we sheer Christmas trees no light gets to the soil but goes to the collective canopy. Also one variable that is almost never discussed is that you don’t need to prune the plant or bush at the same time. You can prune one side or not deep so that the plant or tree does not lose a beat at photosynthetic capacity. Too heavy of pruning at once is not good when you want biomass production because the plant or tree has to slough off part of its root system to regrow which is very inefficient unless you are trying to force transfer of nutrients to an intercrop. There are knives specially designed for this type of pruning if you are going to do large areas but a very sharp panga and thick plastic leg cover on right side leg and a steel toed boot are helpful to prevent cutting into your leg when swinging the panga/machete or long sheering knife. I looked at a lot of articles on this subject for my graduate research paper I wrote on alley cropping. This design also should help with maximal biomass production for Moringa or other trees as well and many perennial plants where the product desired is biomass. To get to a pyramidal shape quickly you may want to plant in a divot or a furrow if the soil has good drainage and use human urine if you are not using it for other higher value crops. And you can trim or nip edges as the plant starts to reach the height and diameter close to the surrounding plants/trees to get the desired pyramidal effect first starting with branches or stems that are in the spaces closest to the proximal plant or tree and later the ones heading in the “x” configuration to the corners which are furthest from their companion plants or trees. You need to leave the ones heading to corners without trimming longer without nipping so they can reach out further. A diamond or cross-checked planting pattern is best.

[Charei_Munene]

This is very interesting. Thanks @Tim_Motis for this crucial info. In Kenya farmers prefer it most for composting and making plant tea/foliar