Root systems provide the foundation for plant development. At the time of seeding and plant establishment, it is important to monitor and evaluate the newly developing root systems; subsequent plant growth depends on them.
Roots are responsible for all water and nutrient uptake by the plant, and they provide the physical anchoring and support of the plant structure. Each plant and crop species has its own “personality” and growth habits, including root systems. Accordingly, root systems have unique characteristics among plants species.
Young plant roots, particularly at the time of germination and stand establishment, are generally the most sensitive plant part to soil and water salinity. In fact, seedling plant sensitivity to salinity can often be measured by approximately ½ of the tabulated salinity tolerance guidelines.
In general plant root systems constitute 30-50% of the total plant dry matter. When post-harvest plant residues are incorporated into the soil, the root systems provide a significant contribution to that plant material and final carbon (C) contributions to the soil, which is an important factor contributing to soil health.
The first thing a seed develops in the germination process is a primary root that grows downward into the soil. We often refer to this as the “stinger” root that extends from a germinating seed. New cells are formed at the tip of the primary root as it extends downward into the soil forming a “thimble-shaped” cluster of cells called a root cap (Figure 1).
The root cap serves as a type of shield that helps the root penetrate the soil matrix and protect the developing root tissue. As the root grows downward into the soil the root cap cells are sloughed off creating a slimy surface that helps lubricate the root as it extends deeper into the soil.
The growing point (apical meristem) for the developing root is just behind the root cap and this is the zone of new cell formation that facilitates root growth and replaces the cells that are sloughed off as the root grows through the soil. The new cells elongate and serve to extend the roots into the soil (Figure 1).
The most active parts of the plant root system for mineral nutrient and water uptake are in the tiny root hairs that are formed in zone behind the apical meristem. Root hairs are only formed in the relatively new and freshly developed root tissue. The root hairs are extremely small, tender, and physiologically active. Healthy fresh young roots and root hairs should be clean and white.
Root hairs are often referred to as “feeder roots” due to their high-level of activity in securing water and nutrients from the soil for the growing plant. In the process of transplanting, it is important to protect the feeder roots as much as possible and promote their health to ensure rapid adaptation to the new soil environment.
Young plants have the capacity to develop basic aboveground tissue to perform sufficient photosynthesis for establishment and growth due to the plant’s ability to take up mineral nutrients and water from the soil from the root system. Sometimes it can appear that plants are not growing rapidly while the young crop is investing energy and resources into root system development, which is the foundation for the subsequent plant growth and development.
The depth of the roots will vary according to the soil physical conditions and effective soil depth, soil fertility and salinity management, plant-available water, and of course the natural rooting characteristics of the plant.
In general, there are two basic types of plant root systems. Broadleaf plants (dicotyledonous) and coniferous plants (gymnosperms) commonly have a taproot system the extends downward through the soil developing root branches from the primary root stem (Figure 2).
Grass plants and their relatives (monocotyledonous plants) produce fibrous root systems that branch extensively and radiate out into the soil from the plant base (Figure 2).
In general, taproots tend to be deeper with extensive branching from the primary root, develop woody tissue on older roots, and are generally long-lived. In contrast, fibrous roots tend to be smaller, short-lived, with less branching.
As roots age, they become more fully developed in conducting nutrients and water to the growing points of the plant, both above and belowground. In all cases, the young and freshly developed root hairs (feeder roots) are the primary zone of water and mineral nutrient uptake.
As root systems age, the older roots will die, and new root tissue is formed. As dead roots are sloughed off, the discarded tissue is attacked by naturally occurring, beneficial soil organisms (bacteria, fungi, protozoa, and worms) the release mineral nutrients and produce soil organic matter. Turnover of root tissue is an extremely important aspect of plant contributions to soil carbon (C), organic matter, and general soil health.
We do not see the plant root systems and we cannot watch root hair development. But it is good to be conscious of root system development since all mineral nutrient, water uptake, and structural support is provided through the roots.
It is necessary to sacrifice a few plants occasionally and evaluate root system health and development. Accordingly, it is good to review and understand normal root structure and function as we work to manage crop plants for optimum growth, development, and yield.
Figure 1. Basic root tip anatomy.
Figure 2. Examples of taproot and fibrous root systems.
Frost and freeze damage affect countless fruit and vegetable growers leading to yield losses and occasionally the loss of the entire crop. Frost damage occurs when the temperature briefly dips below freezing (32°F).With a frost, the water within plant tissue may or may not actually freeze, depending on other conditions. A frost becomes a freeze event when ice forms within and between the cell walls of plant tissue. When this occurs, water expands and can burst cell walls. Symptoms of frost damage on vegetables include brown or blackening of plant tissues, dropping of leaves and flowers, translucent limp leaves, and cracking of the fruit. Symptoms are usually vegetable specific and vary depending on the hardiness of the crop and lowest temperature reached. A lot of times frost injury is followed by secondary infection by bacteria or opportunist fungi confusing with plant disease.
Most susceptible to frost and freezing injury: Asparagus, snap beans, Cucumbers, eggplant, lemons, lettuce, limes, okra, peppers, sweet potato
Moderately susceptible to frost and freezing injury: Broccoli, Carrots, Cauliflower, Celery, Grapefruit, Grapes, Oranges, Parsley, Radish, Spinach, Squash
Least susceptible to frost and freezing injury: Brussels sprouts, Cabbage, Dates, Kale, Kohlrabi, Parsnips, Turnips, Beets
More information:
Given the positive feedback from last week’s article, I thought I’d share with you another video that showcases the cutting-edge advancements in AI technologies. This time, the topic is Digital AI Twins. Reid Hoffman, a renowned expert in AI technologies, has created a digital twin of himself named “Reid AI” using a custom Generative Pretrained Transformer (GPT). Reid AI was trained using content from over two decades worth of Hoffman’s public speeches, podcasts and published books. The result is a digital entity that mirrors Hoffman’s knowledge, insights, and even his conversational style. In the segment, Hoffman interviews his AI counterpart. The conversation is not only entertaining but also very realistic, blurring the lines between human and machine. I was pretty impressed and think you will be too. Given the rapid advancements in these technologies, one can’t help but wonder what’s next in the evolution of AI and how this technology will change the world.
Check it out here or by clicking image below.
Fig. 1. Reid Hoffman meets his AI twin. (Credit: Reid Hoffman).
The Southwest Agricultural Summit that recently took place in Yuma included a breakout session on Thursday, 21 February 2024 titled “New Developments in Weed Control”.
In this session Jose Antonio Cabrera representing BASF technical services for Coastal CA and Arizona provided a review of the new technologies being developed by his company in the Weed Control area. This includes new active ingredients as well as novel encapsulation technologies. The breakout session also included the lecture “Registration Support for Pest Management Tools in Specialty Crops, The IR-4 Project: Purpose and Process” by Roger B. Batts. “The IR-4 Project was established in 1963 by the U.S. Department of Agriculture to ensure that specialty crop farmers have legal access to safe and effective crop protection products. Helps growers address pest management concerns, develops data necessary for the registration of safe and effective pest management solutions with the U.S. Environmental Protection Agency1.
Roger is the Weed Science biologist from the NC State University IR-4 headquarters. If you have questions such as: What is the IR-4 Mission? Why is IR-4 Needed? What are the programs within the IR-4 project? you will find some answers in the IR-4 Presentation Slides here.
We are currently conducting trials in Yuma in coordination with this project that could result in the addition of new labels and weed control tools for our Arizona vegetable growers.
Thank you for attending the SW Ag Summit Weed Science breakout session.
Reference:
Get your free copy of the Weed Seedling Identification Pocket Guide at the Yuma
Agricultural Center.
Results of pheromone and sticky trap catches can be viewed here.
Corn earworm: CEW moth counts remain at low levels in all areas, well below average for this time of year.
Beet armyworm: Trap increased areawide; above average compared to previous years.
Cabbage looper: Cabbage looper counts decreased in all areas; below average for this time of season.
Diamondback moth: DBM moth counts decreased in most areas. About average for this time of the year.
Whitefly: Adult movement beginning at low levels, average for early spring.
Thrips: Thrips adult counts reached their peak for the season. Above average compared with previous years.
Aphids: Aphid movement decreased in all areas; below average for late-March.
Leafminers: Adults remain low in most locations, below average for March.
