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Research

Plant Nutrients - The Mighty Macros

Posted by Jake Emling, CropKing Horticulturist on 11/6/2018

For the second part in this this three-part series we will be discussing the major elements that are typically used in large quantities – calcium, magnesium and sulfur. Some people consider these macro elements and will usually put nitrogen, potassium, and phosphorus also in this category.

 

Part 2: Rapid Relative Humidity Decreases in the Greenhouse

Posted by Jim Brown, Horticulturist on 10/22/2018

Previously on the blog we talked about rapid relative humidity increases and how plant tissue is affected. Today, we’re talking about part 2 – rapid relative humidity decreases. If you missed part one, check it out here!

Part 1: Rapid Relative Humidity Increases in the Greenhouse

Posted by Cropking on 5/24/2018

When the relative humidity in the greenhouse environment either increases or decreases rapidly, the adaptation capabilities of the plants growing in the greenhouse environment may be challenged beyond the breaking point.

It’s the rate of change in the relative humidity rather than just the difference between the old relative humidity and the new relative humidity levels that can challenge the plant’s ability to adapt without resorting to sacrificing some of its tissue.

Nutrient Solution Management in Recirculating Systems

Posted by Dr. Natalie Bumgarner on 11/7/2014
Hydroponic Bibb Lettuce

In recirculating hydroponic systems producing leafy crops, one of the main factors in the control of the grower is the frequency of tank changes (ie pumping out and turning over the recirculating solution). Since we generally manage the solution based on EC, we are assessing the total amount of solutes in the water. We don’t know the balance of each nutrient individually, so tank changes are carried out to try and maintain necessary levels of nutrients. Essentially, our goal is to change the nutrient solution often enough that we don’t have detrimental buildups of unused ions or depletions of important nutrients. Also keep in mind that different water sources have different background ion levels that can slow or speed up imbalances in the nutrient solution.
This tank change practice is really based on cost efficiency. There are nutrient solution management systems that have the ability to manage based on individual ions, but these are much higher cost than the typical systems installed in small to mid scale greenhouses. This hydroponics system cost savings comes at the price of more frequent tank changes that maintain a safe margin of nutrients in solution.

Summer 2014 Oakleaf Trial

Posted by Dr. Natalie Bumgarner on 9/12/2014
Lettuce

Seeding was done by hand into pre-moistened 1” x 1” x 1 ½” cubes of three different media (Grodan 200 ct rockwool, Oasis XL 162, and GrowTech 162). Seeds were germinated in clear water in seeding trays, and were transferred to the nursery and nutrient solution 3 to 5 days after seeding. Seedlings were produced in flowing nutrient solution in the nursery for an additional 10 to 12 days before transplanting. Due to the season, no supplemental lighting was provided during the seedling phase. After transplanting, plants were grown out in the channels for 25 to 28 days until harvest. The nutrient solution was continually cycled through the Fertroller where automatic pH and EC adjustments met programmed solution set points. The pH was maintained at 5.8 by the addition of dilute sulfuric acid. EC was maintained at 1.7 by the addition of concentrated fertilizer solution and source water. Tank changes were carried out every two weeks.

Branching out with Brassicas - Summer trial in NFT production in Ohio

Posted by Cropking on 8/4/2014
Brassicas

In the greenhouses that I visit and crops I discuss with growers, it is clear that lettuce still fills a majority of plant spaces in the NFT system. However, we field an increasing number of questions about the many other leafy crop possibilities. Many of the other leafy options are in the Brassica family - cabbage cousins, essentially. These include kale, mustard, mizuna, and pac choi most commonly.

2014 Tomato Trials- Summer Sneak Peak

Posted by Cropking on 6/12/2014
Hydroponic Tomatoes

For many of the producers that we serve, beefsteak tomatoes are a large majority of their production. However, trends in consumption and competition are increasing interest in specialty cultivars. From demand for farm to school salad bar items to farmers market mixed baskets, there are a range of options for small fruited and colored tomatoes. While visual interest and taste are critical in these cultivars, it is essential that production be adequate and relatively consistent over the season. These two questions are the reason behind this trial. Exhaustive yield data is not possible on the scale that we trial in our test greenhouse, but early evaluation is essential to begin to make suggestions for growers. So, this evaluation was carried out on small plots of fifteen cultivars to assess plant production throughout the season. These are preliminary trials to determine what cultivars to trial more extensively in the future.

Dealing with a Rexless Summer?

Posted by Dr. Natalie Bumgarner on 5/12/2014
Hydroponic Bibb Lettuce

For growers, there exists something of a codependent relationship between them and their cultivar of choice. Due to uncertainties in seed production and demand, there is always the possibility of seed shortages or movement by the industry away from the ‘old faithfuls’. For bibb growers, the popular cultivar Rex is likely going to be less available this summer and early fall and so the questions of what other options to grow certainly are coming to our attention. While it is never possible to guarantee other cultivars will seamlessly replace current ones, CropKing’s trialing and research program is carried out to assist decision making in these areas. So, the best way for me to help growers decide what to grow is to show you what I have observed and measured in our greenhouses here in Lodi.

Investigating impacts of Electrical Conductivity in Nutrient Solutions

Posted by Dr. Natalie Bumgarner on 4/8/2014

In recirculating systems producing leafy crops, one of the main factors in the control of the grower is the nutrient solution electrical conductivity (EC). In many systems, total EC, rather than single elements are controlled due to economics. In most commercial systems using electronic controllers and dosing pumps, concentrated fertilizer solution is added to the nutrient solution any time the solution goes below target EC. So, maintaining consistent EC levels is fairly straightforward, the main question becomes: What is the best EC? The answer to this question is based on two separate factors. The first relates to maintaining needed nutrients in solution. Essentially, the important question is how close to calculated nutrient levels does the solution remain over time. If there are large amounts of ions already in the source water (sodium, sulfate, or calcium for instance), this can cause the nutrient solution to become out of balance more rapidly meaning that ideal ratios of nutrients are not maintained. The second factor involves the movement of water through the plant. At lower EC, it is easier for plants to take up and transpire water. Therefore, under high light and temperature, and low humidity, lower solution EC levels makes it easier for the plant to move water. So, the EC that we use in our systems needs to address these two issues: 1) Maintain adequate levels of plant nutrients, and 2) not stress the plant too much in terms of taking up water needed for transpiration.

Summer to Fall Mixed Leafy Trial

Posted by Dr. Natalie Bumgarner on 2/4/2014
Hydroponic Leafy Lettuce

While lettuce fills a large majority of the spaces in most greenhouse nutrient film technique (NFT) systems in the US, there are many other crops that can be profitable for growers in these systems. In addition to herbs, other leafy crops, such as kale, cress and endive are currently being investigated by growers to address specialty markets. In recent years, more growers are experimenting with these varied leafy crops. However, less is known about crop productivity and timing in relation to both cultivar and seasonal impacts. It is also important to note that unlike bibb and some other lettuce types, most kale, endive and cress are not specifically bred and developed for controlled environment production. So, there is a potential for greater seasonal variability in production than is seen in some of the common bibb lettuce crops. This trial was designed to evaluate a selection of kale and other leafy crops through a range of summer to fall conditions to evaluate their potential for greenhouse growers in the Midwest and Northeast. This trial obviously only used a portion of the cultivars available, but was intended to provide information for future more extensive trials.

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