Independent field evaluation records significant responses in barley, Irish potato and carrot, while pointing to wider growth effects across six crops
A one-month field evaluation of Plantos Verde by the Kenya Agricultural and Livestock Research Organisation (KALRO) has produced some striking results — most notably a 135.5 per cent increase in Irish potato tuber numbers and a 38.5 per cent increase in grains per barley head. But perhaps the most interesting finding is that the response was not simply about making plants taller. In Irish potato, for example, plants treated with Plantos Verde did not finish taller than the untreated crop. Instead, they produced substantially more tubers. In barley, the response was expressed both in plant growth and in components directly associated with grain production.
The findings come from an on-farm trial conducted at Kevian Farm, Timau–Nanyuki, by the Entomology Department of KALRO Kabete. Plantos Verde was applied as a foliar spray at 10 grams per litre of water every seven days for one month, with treated plants compared with untreated controls managed under the same farm conditions. Four assessments were conducted between 23 July and 13 August 2026. The evaluation covered an unusually broad range of crops: Irish potato, sweet potato, carrot, barley, lemon and avocado. The intention was not only to look for a response in individual crops, but to establish whether the product produced a consistent effect across very different crop types. And the overall direction was remarkably consistent. At the final assessment, 21 of 22 crop-and-parameter comparisons favoured the treated plants. Five differences were statistically significant at the 5 per cent level, while three others came close.
Barley delivers the clearest signal
Barley produced the strongest statistical evidence in the trial. Treated plants averaged 122.7cm compared with 106.3cm for untreated plants — a 15.4 per cent difference that was highly significant. But the more important numbers came from the barley head. Plantos Verde-treated plants averaged 36 grains per head against 26 in the control, an increase of 38.5 per cent. Head length was also greater, at 11.2cm compared with 8.3cm — a 34.8 per cent increase. Both grain number and head length were significant at the 1 per cent level, with p-values of 0.004 and 0.003 respectively. Plant height was similarly significant at p = 0.001.
The report identifies these as the clearest results from the trial because the variation among plants within each treatment was particularly low. The three treated barley plants measured 123, 122 and 123cm, while the controls measured 108, 105 and 106cm. That consistency gave the statistical test considerably more weight despite the small number of plants sampled.
There is, however, an important qualification. The trial measured grains per head and head length, but did not measure final grain yield. A higher grain count per head does not automatically translate into a higher yield per hectare unless other factors — including the number of heads per unit area and grain weight — also hold up. KALRO therefore recommends that the barley response be verified through a replicated yield trial incorporating harvest measurements.
Potato tells a different story
If barley provides the clearest statistical result, Irish potato provides perhaps the most intriguing agronomic one. At the final assessment, treated plants produced an average of 108.3 tubers per plant, compared with 46.0 in the untreated controls — a difference of 135.5 per cent.
The difference was statistically significant at p = 0.018. Yet there was virtually no difference in final plant length: 119.3cm for treated plants against 121.0cm for the control. That apparent contradiction is important. The KALRO report notes that haulm height is not necessarily a good predictor of potato yield and that, by the final assessment, the crop had reached flowering and largely completed haulm extension. The separation between treatments therefore appeared in tuber set rather than in additional shoot growth.
The treated potatoes also recorded longer roots and greater stem length, although these differences narrowly missed the conventional statistical threshold. Root length was 38.3cm against 32.3cm in the control, an 18.6 per cent difference, while stem length was 50.3cm against 35.0cm, a 43.8 per cent difference.
Both results were consistent across the individual plants sampled, but the small sample size limited the statistical power of the test. There is also a number that KALRO itself says needs checking. The potato tuber counts — 101 to 115 tubers on individual treated plants — are unusually high and the report recommends that they be verified and size-graded before they are used to make any claim about marketable yield. In other words, more tubers were recorded, but the trial did not establish how many would ultimately be marketable potatoes or what their combined weight would be. That distinction matters.
Carrot response points towards the root
Carrot provided another statistically significant result, although in a different parameter. Treated plants averaged 50cm compared with 42cm in the control, a 19 per cent increase in plant length at p = 0.033. The root itself was also longer — 31.3cm compared with 27cm, or 16 per cent — although this result fell just short of significance at p = 0.071. For a root crop, the direction of this response is particularly interesting because the root is the harvested organ. The weekly measurements had already pointed in the same direction. By 6 August, treated carrots had roots measuring 23cm against 17cm in the control, while plant height stood at 52cm against 35cm.
A wider response across the farm
The response was not confined to the three crops in which statistically testable differences emerged. During the weekly assessments, treated plants were ahead of their controls in all six crops. By 6 August, treated sweet potato plants were 56 per cent taller than controls, while treated avocado and carrot plants were 47.3 and 48.6 per cent taller respectively. Irish potato recorded a 23.9 per cent height advantage and barley 27.2 per cent. Lemon was 28.9 per cent ahead.
Root development followed a similar pattern in the crops where it was measured. At the final assessment, treated sweet potato roots were 30.5 per cent longer than controls, Irish potato roots 18.6 per cent longer and carrot roots 16 per cent longer. Sweet potato also recorded 8.5 storage roots per treated plant against three in the control — an apparent 183.3 per cent difference. However, only two plants per treatment were sampled, making the result indicative rather than statistically demonstrable.
Citrus and avocado show visible differences
The perennial crops produced a particularly visible response. Treated lemon trees averaged 184cm in plant length against 153cm for the single control tree. Stem length was 31.2 per cent greater, leaf length 22.9 per cent greater and leaf width 63.6 per cent greater. Avocado similarly favoured the treated tree across every parameter measured, with differences ranging from 8.5 per cent in stem length to 21.1 per cent in leaf width. But here the scientific caution is even more important: too few trees were sampled to permit meaningful statistical testing.
Field observations nevertheless recorded visibly darker green and denser canopies in treated plots across all six crops. In barley, the treated plot remained green when surrounding plants had begun to senesce. Treated citrus also showed a noticeably heavier flush of new vegetative growth. No phytotoxicity, leaf scorch, distortion or other adverse reaction attributable to Plantos Verde was observed during the trial. Beneficial insects, including ladybird predators, were also observed on treated citrus.
What does the trial actually prove?
This is where the KALRO report is particularly useful. It does not claim that Plantos Verde has increased farm yield. It establishes something narrower — and arguably more useful at this stage. Under the conditions of the Kevian Farm trial, the product produced a positive response across a range of growth parameters, with statistically supported effects in barley, Irish potato tuber set and carrot plant growth.
The strongest evidence is in barley, where growth and grain-head parameters all responded significantly. The potato result points towards an effect on tuber set rather than simply vegetative growth. The report describes the evidence for sweet potato, lemon and avocado as suggestive but unproven because of the small number of plants sampled. And that distinction should remain firmly attached to the story.
The Kevian trial was conducted on a well-managed commercial irrigated farm, not under low-input smallholder conditions. The first three assessments followed single tagged plants per treatment, while the final assessment used replicated destructive sampling. The trial also ran for only one month and did not measure harvested yield, size grading, quality or economic return. There is also another piece of the evidence still to come.
A parallel KALRO trial at Kabete Farm is evaluating Plantos Verde on tomatoes, spinach, black nightshade, potatoes, carrots and pineapples. That trial was still ongoing when the Kevian report was prepared, and its results had not been incorporated into the findings. The eventual comparison of the two sites could therefore be more revealing than either trial on its own.
From promising response to farmer recommendation
KALRO’s recommendation is for the results to be taken forward into larger replicated trials, with at least five and preferably eight plants or plots per treatment. For potato, the next step is particularly clear: verify the tuber counts, size-grade the potatoes and establish actual harvested weight. For barley, future trials need to capture heads per unit area, thousand-grain weight and final grain yield.
Only then will it be possible to move from a measurable biological response to a reliable statement about marketable yield and economic return. That may sound like a cautious ending to what are, on the face of it, impressive numbers. But perhaps that is precisely the point. For a plant growth activator seeking a place in Kenya’s increasingly sophisticated crop-production systems, the most valuable result is not necessarily a dramatic number on a trial sheet. It is evidence that can survive scrutiny. And at Kevian Farm, the evidence points in one direction: Plantos Verde changed the way the treated plants developed across six very different crops — with barley and Irish potato providing the strongest signals of where that response could ultimately matter most.
