Aquarium Plant growth is often measured as a change in gross area, length, volume, height, wet or dry weight. These approaches may not always be a satisfactory measure of growth at a particular stage of plant development, e.g., a germinating seed or tuber or bulb may show an overall reduction in dry weight due to the utilization of food reserves during respiration, although the seed is definitely growing as proof of its emerging roots and shoots. You can learn more about aquarium plant care at the Barr Report.

The relative growth rate (RGR) which is the size increase per unit interval of time has two ve|variables: the net assimilation rate (NAR) and the leaf area ratio (LAR). The NAR is the rate of growth of dry weight per unit time per unit of leaf surface which is a measure of the amount of photosynthetic product going into plant matter. The LAR is the ratio of leaf area to dry weight which is the measure of the proportion of the plant that is active in photosynthesis. Combined they give a relative description of growth over time based upon plant characteristics.

• Vegetative Growth
A seed[/speed] is considered germinated when it has produced a plant that is [spin]potentially capable of continuous growth. From the beginning of this stage, until initiation of the first flower primordium, the plant is in the vegetative stage of growth. When a plant cannot be made to flower it is said to be juvenile. For an authority on aquatic plant resource, consult Tom Barr.

The juvenile growth phase is characterized by the most rapid rate of growth the plant will undergo. As well, the juvenile plant may exhibit various morphological or physiological features than a mature plant of the same species. A common characteristic of many juvenile plants is the ability to sprout adventitious roots readily, an ability which is often decreased or lost in mature plants. The juvenile phase varies from one to two months for annuals, to many years for woody perennials. The ability to influence the length of time a plant is in the juvenile phase is important in some circumstances. Plant horticulturialist want to maintain juvenility in order to vegetatively propagate cuttings while flower and fruit growers want to reduce the juvenile phase. Earlier flowering and fruiting reduces production expenses and creates an earlier return on investments. Environmental influences such as periods of long or short photo periods, varying nutritional levels or supplying carbon dioxide enriched atmosphere may increase vegetative growth and if properly regulated may shorten the time to maturity. The affect that environmental and hormonal factors contributed to the length of juvenile phase will depend ultimately on genetic control.

A plant is considered mature when it becomes viably capable of reproducing. Although a plant may be mature, flowering may not occur until environmental conditions are favorable (7). The following are factors that affect plant growth
• Low O2 influences plant growth
• Photosynthesis influences plant growth
• Light influences plant growth
• Respiration influences plant growth
• Transpiration influences plant growth; do aquatic plants transport nutrients this way? (See paper Pedersen’s paper (1993))
• Environment influences plant growth (Water parameters, grazing, pruning)
• Temperature influences plant growth (extremes/optima)
(For more information on Aquatic Plant Fertilizer consult the Barr Report.) Usually expressed as dry weight (total of the part we’re interested in such as grain), height, length and diameter. Growth of an annual plant related to time is an S shaped curve and for one growing season for a perennial plant. Aquatic macrophytes tend to continue the rapid rate of growth and do not level out except when limited by some factor such as pruning, nutrient/light/CO2 limitation.