Chemistry Reference
In-Depth Information
accumulated in grain and straw, which are given not only the process of photosynthesis, by
transport in plants, but also by the ratio and content of energy-rich substances, particularly
sugars, proteins and fats.
High temperature stress of
Brassica napus
and other crops during flowering reduces micro
and megagametophyte fertility, induces fruit abortion, and disrupts seed production [64].
3. Stress during new seed germination - seed stress tolerance
It is known that it is possible to provide selection for cultivar resistance to stress already at the seed
and at the seed germination stage and on the quality of the plant root system. Quality of the
embryonic roots is important for the following growth and also roots development. In the juvenile
phase and in later stages,
these are the same genotype! This is a general biological regularity. At each
experiment very good relationships between above named traits exist.
For example it is possible to determine the genetic relationship between salt tolerance
during seed germination and vegetative growth in tomato by comparing quantitative trait
loci (QTLs) which confer salt tolerance at these two developmental stages. However,
simultaneous improvement of tolerance at the two developmental stages should be possible
through marker-assisted selection and breeding [43, 44].
Germination is also regulated by abscisic acid content. The content of abscisic acid in the
seed is determined by genotype and conditions during the growth of seeds [78].
Signal transduction pathways, mediated by environmental and hormonal signals, regulate
gene expression in seeds. Seed dormancy release and germination of species with coat
dormancy is determined by the balance of forces between the growth potential of the
embryo and the constraint exerted by the covering layers, e.g. testa and endosperm. GA
releases dormancy, promotes germination and counteracts ABA effects. Ethylene and BR
promote seed germination and also counteract ABA effects. We present an integrated view
of the molecular genetics, physiology and biochemistry used to unravel how hormones
control seed dormancy release and germination.
There are several ways to improve the adaptability of plants to the variable environmental
stress conditions. Physiological studies of plant integrity have shown that the plant
responds to stressors by modifying more than 100 physiological traits. The presented results
[26] confirmed that seed vigor and plant vigor (quick escape from any stress) are in
significant correlation with yield and root quality system.
Selected basic traits of seeds (vigor, germination percent, and emergence) and especially
stress tolerance during germination of the seeds to the high and low temperature during
day and night have significant influence on the quality of the root development. Plants with
well-embryonic roots and high energy potential germination escape the stresses during
begin the growing period, especially at drought conditions and are guarantee with high
probability quality of the root system [64, 78,90].
