Скачать или смотреть Tomato plants grown in Growstones and Rockwool 30 hours without irrigation

10 month old TOV plants growing in an hydroponic greenhouse at The University of Arizona in Tucson show first visible signs of wilting after 30 hours without water in a typical monsoon weather (from August 1 at 6:15 am to August 2 12:15 pm, 2007). Tomato plants were grown in two types of Growstones slabs [large and small pore size, referred to as Earthstone 2 and 3] and compared with plants grown in Rockwool Expert slabs. First visible signs of water stress were noticeble at the same time in all cases. Since Growstones are a drier hydroponic substrate than Rockwool, this result might be due to the fact the drainage wholes in Growstones was 2 cm from the bottom of slabs, allowing for some water storage while in Rockwool it was closer to the bottom of the slab. The cloud cover present during the day also contributed for the long period without any visible signs of water stress (wilting).

1 year later *****************************************
Great to get these many comments and questions. I really appreciate the interest, curiosity or. whatever you wanna call it. So let me see if I can clarify some of the questions related to the plants.

In this video, what you are looking at is a mature indetermined tomato crop growing inside a greenhouse in Arizona.

In indetermined tomato plants, three leaves are initiated between two successive fruit trusses, continuously. This means that the growing tip of the plant is always developing new shoots, which develop into leaf and flower trusses. As young leaves expand and flowers open and set fruit, new leaves and flower trusses are developed at the growing tip of the plant (the apical meristem). For most of the life of the plant the development of leaves, shoots, stems, overlaps with developmment of flowers and fruits. Only the main stem is allowed to grow by pruning any lateral shoots that tend to develop throughout the crop season. Because the main stem keeps on growing, at the end of a crop season the stem can be as long as 30 feet.

In order to manage the continuous growth of the stem, every week each plant has to be 'leaned and lowered'. This allows keeping the actively growing part of the plant (the 9 feet up straight portion of the plant showing in the video), within the volume of the greenhouse which climate can be most easily controlled or managed.

These are the types of tomato plants used in greenhouse production as they allow longer production periods, which is one of the main reasons why one chooses to grow in a greenhouse in the first place.

Now you still might be asking why cant we see any tomatoes in the video? Fair enough! But the reason is simple - the ripe tomatoes, which would have been located under the last set of leaves in the plant (not the best angle to capture that), were harvested a few days earlier as we were getting ready to finish the crop. The tomato trusses developed later (younger trusses) located progressively higher on the stem were still green and developing. You can't see them because the leaves cover them. Through the season, the number of leaves allowed to remain on the plant is controlled by leaf pruning. The number of leaves left on the plant depends on several factors but mostly on the season (light availability and temperature - more leaves are left in the summer because they help with cooling the air inside the greenhouse). That is why there were so many leaves on these plants. During the winter each plant would have less leaves, making it easier to see the green developing fruits.

In the southwest of the US, the crop season for indetermined greenhouse tomatoes is about 10 months with a production period of about 8 months (usually in Tucson, AZ the crop season goes from mid August till end of May-beginning of June, with first harvest beginning of November). Because its difficult to cool during the summer and yields tend to decrease after a certain period of continuous production, it is common to just take the crop out and replace with a new crop, and start all over again. Large greenhouse operations, which can keep the air temperatures within near optimum ranges throughout the year, can produce all year round. They still take the plants out after 10 months but before this takes place, a new crop is placed next to the old one. When the new crop enters in production the old one is taken out this is called interplanting.



This is clearly a very different growth and development pattern than that of a determined tomato plant. Those are grown in the field, are characterized by a bush-type plant in which the production of leaves and the production of fruits is separate in time, and is characterized by short production periods.