why do seeds germinate better in warmer temperatures
Using laboratory incubation, the response of seed germination and emergence to variability in temperature and light was examined for spider flower (
Cleome gynandra L. ), amaranth ( Amaranthus cruentus L. ), non-heading Chinese cabbage ( Brassica rapa L. subsp. chinensis ), nightshade ( Solanum retroflexum Dun. ), pumpkin ( Cucurbita maxima Duchesne), tsamma melon ( Citrullus lanatus Thunb. ), Jew s mallow ( Corchorus olitorius L. ) and cowpea ( Vigna unguiculata (L. ) Walp. ). Effect of temperature on seed germination and emergence was monitored under continuous darkness and at constant temperatures that ranged from 4 P `C to 44 P `C with 4 P `C increments. The effect of light on seed germination was measured at 25 P `C. Temperature affected germination rate and final germination percentage of all species tested in ways that were characteristic for each of the species tested. Generally, optimum germination occurred at temperatures ranging between 29 P `C and 32 P `C but at higher temperatures for V. unguiculata (36 P `C) and C. olitorius (35 P `C).
The minimum temperature for germination ranged between 8 P `C and 15 P `C, and the maximum between 36 P `C and 44 P `C. Optimum temperatures for seedling emergence ranged from 25 P `C to 31 P `C, the maximum between 32 P `C and 40 P `C and minimum between 2 P `C and 13 P `C. Light positively ( p P P 0. 01) affected onset of germination in A. cruentus, B. rapa subsp. chinensis and C. olitorius, and final germination percentage of B. rapa subsp. chinensis, C. lanatus and S. retroflexum. The results suggested that under South African conditions, seeds of the eight species will typically germinate optimally as temperatures rise during spring before the occurrence of very hot temperatures in summer. Due to their positive response to light, germination of B. rapa subsp. chinensis, C. lanatus and S. retroflexum seeds is expected to be optimal when sown at or close to the soil surface. By Mary H. Dyer, Does weather affect plant growth? It sure does! Itвs easy to tell when a plant has been nipped by, but high temperatures can be every bit as harmful.
However, there is a considerable disparity when it comes to temperature stress in plants. Some plants wilt when the mercury begins to climb, while others are at their best in extremes that would leave weaker plants begging for mercy. How Does Temperature Affect Plant Growth? High temperatures affect plant growth in numerous ways. The most obvious are the effects of heat on, in which plants use carbon dioxide to produce oxygen, and respiration, an opposite process in which plants use oxygen to produce carbon dioxide. Experts at Colorado State University Extension explain that both processes increase when temperatures rise. However, when temperatures reach uncomfortably high limits (which depends on the plant), the two processes become unbalanced. , for example, get into trouble when temperatures exceed about 96 degrees F. (36 C. ). The effect of temperature on plants vary widely, and is influenced by factors such as exposure to sunlight, moisture drainage, elevation, difference between day and night temperatures, and proximity to surrounding rock structure (thermal heat mass).
Does Temperature Affect Seed Growth? is a miraculous event that involves a number of factors that include air, water, light, and, of course, temperature. Germination increases in higher temperatures в up to a point. Once the seeds reach optimum temperatures, which depends on the plant, germination begins to decline. Some plant seeds, including cool season vegetables, like and, germinate best in temperatures between 55 and 70 F. (13 to 21 C. ), while warm season plants, such as and, germinate best when temperatures are between 70 and 85 F. (21 to 13 C. ). So whether itвs extreme heat or cold, temperature does affect plants and their growth. This is one of the reasons why itвs important to check a plantвs hardiness and see if it is compatible to your particular. Of course, where Mother Nature is concerned, even when grown in optimal conditions, you cannot control the weather.
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