Hass in Half the Time: Testing and Applied Research with the F-751 Avocado Quality Meter

Scott Trimble

April 26, 2021 at 10:05 pm | Updated August 8, 2022 at 9:28 pm | 8 min read

Andrea Rivera and her team at GAMA are cutting their testing time in half using the F-751 Avocado Quality Meter.

In our most recent interview, Application Scientist Galen George sits down with Andrea to chat about her current projects avocado, and how her team has integrated this time-saving technology into their process.

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About Andrea

headshot of researcher Andrea Rivera standing outside
I am an Agricultural Engineer that has developed a career in the Chilean fruit industry, specialized in applied research. I have been implementing and evaluating field trials, which also involves fruit quality and postharvest assessments. I have been working with GAMA for almost 6 years, coordinating and participating in anctivities related to the development of our avocado and citrus assays.

GAMA is a Research and Development Company located in the city of Quillota (Chile), led by Francisco Gardiazabal and Francisco Mena. We are focused on conducting applied assays in subtropical crops, mainly avocado and citrus. One of our main objectives is to provide to the industry reliable information that will allow it to increase both yeild and fruit quality. This objective always goes hand in hand with the development and implementation of technologies according to the requirements of the market at a national and international level.



Galen:    Hi, my name is Galen George and I’m an application scientist here at Felix Instruments. And why don’t you go ahead and introduce yourself and tell us about what you do and, you know, how you got to where you are, kind of what your background is in and what you’re currently doing for the company.

Andrea:    Okay. Well my name is Andrea Rivera. I’m working at Gama, that is a plant research company. I’ve been here for almost 6 years. I’m an agricultural engineer, that’s the name of what I do too, because there is no specific label to what I do. We cover a lot of activities here, especially with avocados and citrus – mandarins, oranges, lemons, and, of course, avocados. I have been here for 6 years. Before that I did my Masters’ in Australia. Before that I did applied research but in sweet cherries, so my background is mainly in applied research. After my Masters’ in Australia I came here. As I told you before I have been here like for almost 6 years.

What we do in general is we try to get results in different areas to, for example, increased yield, number of fruits, try different products from chemicals, components, industries. We do our own research too. My bosses are important consultants here in Chile, in avocados and citrus. So they go every day to the orchards. They talk with the producers, and they talk about problems that could arise on those orchards, and that is when we come in and we try to solve those problems in irrigation, fertilization, cultural practices for example, at harvest. We do post-harvest too. Of course we measure dry matter. We analyze the quality of the fruit to improve harvest and quality measurements, and for citrus too.

Galen:    So, is it safe to say, so you’re researching all of these different factors that could influence the potential yield and quality of the avocados. Right? And are we talking mostly about Hass avocados?

Andrea:    Yeah.

Galen:    Is there any green skin, or is it mostly Hass?

Andrea:    It’s only Hass avocado. Hass avocado is like 99.9 production here in Chile. We have, of course, some green avocados, but that’s mostly in houses, like in my backyard I have like a Fuerte variety or something like that. But they… you can find maybe sometimes in the supermarkets some Fuerte or there are some other varieties that are green skin, but the production is mostly–almost totally Hass.

[Testing – 1 person, 1000 measurements]


Galen:    So previously with your work, can you kind of walk us through how you would go about taking your dry matter measurements, how you would go about sampling in the fields, and the limitations to that approach that you were using?

Andrea:    Yes. Well, for most of our assays in avocados we measure dry matter. We don’t have a research project specifically for measuring dry avocado, but because you need to not only increase the productivity of your orchard, but you also have a good quality fruit. So, that’s why in almost every assay we measure dry matter. But we don’t measure at the orchard itself because here in Chile most of the orchards of Hass avocados are in high slopes. So it’s quite difficult. Yeah, you can work there with more or less difficulties, but you cannot go with equipment, because what if you fall? What if your equipment falls to the ground? So no. For each treatment that we have in whatever assay that we are measuring, we take a sample of 30 fruits per treatment, and we measure 4 points in each fruit.

So in total we have 120 measurements per treatment. And we do that because we are doing research, so we want to have the best assessment of the treatment. And talking with you, you told us that, for example, if it’s commercial you measure one point per fruit, but if you are doing research it would be better to have 4 measurements per fruit, so that’s what we do. And before using your instrument we were using the microwave, and we already measured 30 fruits, and weighed that much per treatment. Consider that per treatment we have like 20 to 25 trees, more or less. So, we take a sample of 30 fruits, that will be a great number, but the variability of dry matter in a tree itself is very, very great. So you can have, in just one tree, fruits that range for example from 20 to 30 value of dry matter, or it could be more, maybe you can find sometimes at 17 and 32. So the range is quite large. So that’s why we take 30 fruits per treatment.

Of course it’s a time saver because using the microwave we could measure like, I don’t know, 8 samples, 8 treatments. But we needed two persons to do the microwave analysis. So using your model we only need one person, and we can do 8 or 9 per day, one person using your instrument, versus the microwave where you need… yeah. Maybe you can do the same amount, but you need two persons, so it’s double.

(4 points per fruit x 30 fruits per treatment x 8-9 treatments per day = 960-1080 measurements)

Galen:    Right. Well, that’s great. And I do think it’s actually really valuable that you are taking those 4 points. As you know, the dry matter is not a very homogenously distributed attribute throughout the entire avocado. So, when you’re taking a scan of one single point you’re actually only getting the dry matter of that area of the avocado, not necessarily what the whole thing is representative. As if you are taking, you know, taking multiple scans is kind of analogous to destructively sampling, you know, more of the actual flesh of the fruit and the microwaving all of that as one.

So, is there any really interesting research that you guys have kind of helped out with lately that you want to talk about as far as treatments or anything like that that you’ve seen that is helping out a lot with the yield or any kind of problems with quality?

[Current Research – Fertilization Timing]


Andrea:    Maybe I can talk to you about assays related to fertilization. We are doing nitrogen, we use urea. So the amount of nitrogen that you apply to trees is already well known. Per season it’s like 600 kilos of urea per hectare, and you apply that in three times here in Chile – October, January, and March/April – and in the fruit flush. That’s what commonly we do here in this area. But we are trying to assess if we can change the timing of the application of urea. The same amount for every treatment, but applied at different months. We are trying different months, also for example applying urea or nitrogen all year, and we are looking at what is happening. We don’t have any conclusive results right now because this assay has two years. So there are some tendencies, but we cannot say for sure which treatment is better.

We usually conduct a trials for 4 years to reach a conclusive assessment. But related to dry matter, we measure not only at harvest dry matter, we do measurements like starting July until harvest, every month for every treatment. We currently have like 11 treatments. So, okay, we of course always look for the yield which treatment is better, but we are also looking at, okay, I’m applying the same amount of nitrogen but at different times. What will happen with the maturity or the ripening of the fruit? So that’s why we are looking at what is happening every month, not only at harvest. To know if for example, it will reach maturity sooner or later depending on the treatment. As I told you, we don’t have any conclusive results right now, but we’re looking at what will happen if you apply nitrogen at different months.

Galen:    Mm hm.

Andrea:    And what will happen not only with yield, but also with dry matter and of course the quality of fruit too at harvest.

Galen:    Well, I’m really excited to see what kind of results you get out of that. Was there research that you or another group conducted that determined how you guys are currently performing your fertilization at these specific months? Was there research that indicated that these were the times to do it? Or was that just kind of in place?

Andrea:   I cannot recall right now which assay it was. I guess it was like years ago, maybe in the 90s or 80s, maybe research done in other countries. But we are looking at the physiology of the tree. So, when do you need your nitrogen? At what moments do you need it? Why in October? Why in January? Why in March/April? You have in October flowering and fruit set here in Chile. And also the roots are very active. So, that’s a very good moment to apply nitrogen that will supply for the fruits. You also have shoots growing, so it’s very high competition and you need a very high amount of nitrogen. It will also depend if you have a high load or low load of fruit in the tree in the sector that you’re analyzing. So that’s why, for example, in October/November you need to apply nitrogen. Why in January? Because you also have the branches that renew from October to January. You already have fruit set, but you need to get more food for the tree so it can keep growing. You also have root activity in that moment. And in March you have another peak for root activity, lower than in October, but you are entering autumn at that time too so will have more resources, more nitrogen in the roots for spring.

So you are supplying the amount of nitrogen that you need for spring. Buds, flowering, and everything. So that’s why we’re applying at those moments. And why we’re trying to change those timings is because you have also what is happening in the buds differentiation. For example, here in Chile we have a flowering that extends for two months. It could be mid-September until mid-November, so we are applying at what moment?

Maybe it could be better to apply at the beginning of the flowering. Maybe it could be better to apply later, in November. It’s better to apply, for example, instead of January in December. So you are looking at differentiation of the buds, more or less. So, we’re trying to discover what will happen if we change, looking at the physiology of the tree. We don’t do a microscopical analysis of buds. We do applied research, so we look at the final yield per year. But you can try to explain what happens every month looking at the physiology of the tree, at least here in Chile. Of course it will be different in the US or in another country, but the variation will be in the months – what happens in the tree is the same for every place.

Galen:    Well that’s… I mean it’s really great to see the continuation of research. You know, a lot of times I feel like a study is published, and we kind of take it as definitive fact and we never expand upon that. So it’s great to see that you guys are doing some work to kind of investigate why and maybe see improvements with changing these intervals of fertilization.

Andrea:    Yeah.

Galen:    And that’s great that we can incorporate the 751 to help you with the dry matter measurements.

Andrea:    Yeah.

Galen:    Not just, you know, after harvest, but to track maturity stages.

Andrea:    Yeah.

Galen:    That’s great. Well, it’s been 15 minutes here and I would like to say thank you so much  for this interview, and it was really great to learn from you about what you guys are doing down in Chile, and if you have any research that you want people to know about, feel free to send those to us and we’ll get them out to everyone.

Andrea:    Thank you very much to you too.

Galen:    Yeah.

Andrea:    And for this conversation and everything.

Galen:    Thank you so much, Andrea. Have a great day.

Andrea:    You too. Bye bye.

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