The Biosphere Blog

What is a Sucker? The roots of many plants and trees never see the light of day, and spend their lives pushing ever downwards and sideways in pursuit of moisture and nutrients. The roots of other species however will occasionally send up suckers, or… more »

A plant root is an organ, and last week we looked at the specialised regions along a root in a longitudinal (lengthwise) section. Today we go in at right angles and examine what is revealed by a cross-sectional cut across a root. Before doing so, a very… more »

A plant root is an organ, and like all organs (plant or animal), has specialised regions marked by specialised tissue. This post outlines these, with an emphasis on the longitudinal section (a cut along the long axis) of a young, growing root. Next week… more »

Roots — so often out of sight and out of mind — have four essential functions. They anchor a plant in the ground, they uptake water and nutrients, they store excess food, and they synthesise some phytohormones (plant hormones) and other compounds. The… more »

Ecodormancy is the third and last stage of dormancy. It is a ‘less dormant’ state in which a tree becomes more responsive to external environmental factors, but is prevented from growth because of response to those factors, such as the still… more »

Endodormancy is the second, and true stage of dormancy. During endodormancy the tree is in such a deep state of rest that it cannot respond to favourable environmental factors even if it wanted to. This probably protects it from responding to brief,… more »

Before Getting Started: This and the next two posts will be referring to genes and the proteins they code for. Writing the two can be confusing, as they often have the same name! This becomes even more confusing when the qualifying terms… more »

Last week we looked at the three stages of dormancy: induction, endodormancy, and ecodormancy. Some species enter dormancy when the number of daylight hours reduces, while others seem to respond to decreased temperatures. In contrast, most species… more »

Many temperate woody perennials, including the jujube tree, enter dormancy during winter so as to survive the very low temperatures and greatly reduced sunlight of that season. During this period all activity and other signs of life cease — leaves fall… more »

What started out as a little blog about jujube trees has grown and evolved somewhat, and far past its original scope of ‘just’ the tree! While most posts have not been specifically about the jujube tree, they’ve still been relevant and… more »

Chromium (Cr) Chromium (Cr) occurs naturally in soils from weathered rocks, but mostly as the chromium(III), or Cr3+, ion. This ion clings tightly to the negatively-charged sites of clays and organic matter, or forms insoluble compounds unavailable to… more »

I’ll open this post by briefly referring back to nickel (Ni) in last week’s post: the element that walks a tight line between being beneficial and being toxic. Nickel (Ni) sits right next to cobalt (Co) on the Periodic Table, and closely… more »

The macronutrients and micronutrients covered earlier are the main twelve essential for plant survival and growth, and the ones routinely included in complete fertilisers. A few other nutrients not often mentioned also have beneficial roles, and these… more »

Deficiency Symptoms Which Appear on Oldest Leaves First The following deficiencies appear on older leaves first as the elements involved are very mobile within a plant. If a nutrient on this list isn’t available in sufficient quantities to satisfy… more »

Availability to Plants Boron in soil ranges from 20 to 200 ppm (parts per million), but most of that is unavailable to plants. The boron that is available ranges from 0.4 to 5 ppm, and mostly as the compound boric acid, B(OH)3. Boric acid readily… more »