Orchard applications of sodium hydrosulfide increase the yield of avocado (Persea americana Mill.) cv. ‘Hass’
A three-year field trial demonstrates that applying the hydrogen sulfide donor sodium hydrosulfide (NaHS) to 'Hass' avocado trees during winter and summer significantly increases fruit yield by approximately 35% in weight and 48% in number by mitigating premature fruit abscission and enhancing climate resilience.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine you are a gardener trying to grow the perfect fruit, but your plants are living in a world that can't decide if it's a freezer or a furnace. This is the daily struggle for avocado trees, specifically the famous 'Hass' variety. These trees are like sensitive artists; they bloom beautifully but are easily spooked by extreme temperatures. If it gets too cold in winter, they shiver, and if it gets too hot in early summer, they panic and drop their baby fruits before they can grow. This phenomenon, known as "June drop," is like a mother bird abandoning her nest because the sun is too hot, leaving the farmer with an empty basket.
To help these trees, scientists use a trick called "chemical priming." Think of this as giving a plant a tiny, safe dose of a stressor to wake up its internal immune system, kind of like how a vaccine teaches your body to fight a virus before you actually get sick. One of the stars of this show is a molecule called hydrogen sulfide (H2S). While the name sounds like rotten eggs, in the plant world, it's actually a helpful messenger that tells the tree to stay calm, fight off damage, and hold on to its fruit. The big question researchers have been asking is: Can we spray this helpful messenger on real avocado orchards to stop the trees from dropping their fruit and to make sure farmers get a bigger harvest, even when the weather is acting up?
This is exactly what a team of researchers set out to test in a real-world avocado orchard. They took 80 'Hass' avocado trees and split them into two groups: a "control" group that got a plain water spray, and a "treatment" group that got a spray containing sodium hydrosulfide (NaHS), a substance that releases that helpful hydrogen sulfide signal. They didn't just spray once; they treated the trees three times during the cold winter and three more times during the hot early summer when the fruit is most likely to fall off.
The results were pretty exciting. Over three years, the trees that got the special spray consistently produced more fruit than the ones that didn't. By the end of the study, the treated trees had produced about 35% more fruit by weight and nearly 48% more fruit by number compared to the control trees. It's as if the treated trees were holding onto their babies much tighter, refusing to let them drop even when the summer heat tried to shake them off.
One of the coolest parts of the study was looking at how the trees behaved individually. Avocado trees are famous for "alternate bearing," which is like a mood swing where a tree has a huge year one year and a tiny year the next. The researchers found that the trees in the orchard were all out of sync with each other; some were having a "good year" while their neighbors were having a "bad year." Despite this chaos, the sodium hydrosulfide spray worked for everyone. It didn't matter if a tree was naturally in a high-yield or low-yield phase; the spray helped them all produce more. This suggests the treatment works independently of the tree's natural rhythm.
The scientists believe the magic happened because the summer sprays, timed perfectly with the "June drop," helped the trees fight off the heat stress that usually causes them to abort their fruit. The hydrogen sulfide likely acted as a shield, stopping the chemical signals that tell the fruit to let go. Interestingly, in the third year, the treated trees actually had fewer flowers than the control trees, yet they still ended up with more fruit. This suggests the spray didn't just help the trees make more flowers; it helped them keep the fruit they did have, essentially changing the tree's strategy from "make lots of flowers and hope for the best" to "make fewer flowers but take really good care of them."
While the study didn't dive deep into the molecular secrets of exactly how the spray worked inside the tree, the results strongly suggest that this method could be a powerful tool for farmers. It offers a way to protect crops from the wild swings of climate change, turning a shaky harvest into a reliable one. The researchers note that while the current spray works well, future work might focus on creating slow-release versions of the chemical to make it even easier for farmers to use in the field. For now, though, it looks like a little bit of hydrogen sulfide could be the secret sauce to saving the avocado harvest.
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