Some plants such as lettuce require cool conditions for germination (<10 oC), a condition known as thermo-dormancy. This reflects the evolution of the wild parent species in cooler environments and growth cycles limited by higher summer temperatures. Transforming live but dormant seed into new healthy self-sufficient plants requires care and planning. The conditions in which seed is stored before use greatly affect the vigour and quality of plants post-germination. Seed which is stored too long or in unsuitable environments deteriorates resulting in unthrifty seedlings.
Seed is either sown directly into soil or into compost designed especially as an aid for germination. These composts contain carefully balanced nutrient formulae which provide larger proportions of potassium and phosphorus compounds which promote rooting and shoot growth. The amounts of nitrogen needed at and immediately post-germination are limited. Excess nitrogen immediately post-germination will cause over-rapid growth which is susceptible to pest and pathogen damage.
Minor nutrients will also be included in composts which ensures the establishment of efficient metabolic activities free from deficiency disorders. Composts require pH values at ~ 7.0 for the majority of seedlings unless they are of calicifuge (unsuited for calcareous soils) species where lime requirement is limited and the compost pH will be formulated at 6.0. Additionally, the pC will be carefully tuned ensuring correctly balanced ionic content avoiding root burning disorders. Finally, the compost should be water retentive but offering a rooting environment with at least 50 percent of the pore spaces filled with air. Active root respiration is essential while at the same time water is needed as the carrier for nutrient ions.
Seedlings encountering beneficial environments delivering suitable temperatures will germinate into healthy and productive plants.
Some plants such as lettuce require cool conditions for germination (<10 oC), a condition known as thermo-dormancy. This reflects the evolution of the wild parent species in cooler environments and growth cycles limited by higher summer temperatures.
Careful husbandry under protection such as in greenhouses provides plants which can be successfully transplanted into the garden. The soil receiving these should be carefully cultivated, providing an open crumb structure which permits swift and easy rooting into the new environment. It is essential that in the establishment phase plants are free from water stress. Measures which avoid predation from birds such as pigeons may also be required.
Netting or the placing of cotton threads above plants helps as a protection measure. Weeds must be removed otherwise competition will reduce crop growth and encourage pests and diseases, particularly slug browsing. Finally, the gardener will be rewarded for his/her work with a fruitful and enjoyable crop!
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is about the various uses of nitrogen.
Nitrogen – an imperative part of DNA
The polymer that makes up the genetic code of is a sequence of nitrogen bases laid out on a backbone of sugar and phosphate molecules and blended into a double helix.
The nitrogen bases are translated into proteins and enzymes which regulate most our system’s biochemical reactions.
RDX is a nitrogen explosive. This means its explosive properties are primarily caused by the presence of many nitrogen–nitrogen bonds, which are extremely unstable, especially as nitrogen atoms want to come together to produce nitrogen gas due to the triple bond.
Ultimately, the more nitrogen–nitrogen bonds a molecule has, the more explosive it is. RDX is normally combined with other chemicals to make it less sensitive or less likely to explode.
One of the most powerful explosive chemicals is PETN, containing nitro groups and nitroglycerin in dynamite. Despite its powerful explosions, the chemical rarely will detonate alone. PETN was used frequently during World War II, whereby PETN was used to create exploding bridgewire detonators, using electric currents for detonations.
Among the least stable explosives is aziroazide azide, with 14 unstable nitrogen bonds, most of them bonded into unstable nitrogen–nitrogen bonds. Touching or handling this chemical can cause it to detonate, making it one of the most dangerous non-nuclear chemicals.
Nitrogen and plants
Nitrogen plays a significant role for plants to keep healthy. Plants usually contain 3-4% nitrogen in their above-ground tissues. Nitrogen is a major component of chlorophyll which plants use to capture sunlight energy to produce sugars, and a major component of amino acids, which are the building blocks of life.
Overall, nitrogen is a significant component to DNA, a key nutrient to plants, and the uses of nitrogen in everyday life span across various chemical industries including the production of fertilisers and explosives.