Dormancy is when there is a lack of germination in seeds or tubers even though the required conditions (temperature, humidity, oxygen, and light) are provided. Dormancy is based on hard seed coat impermeability or the lack of supply and activity of enzymes (internal dormancy) necessary for germination. Dormancy is an important factor limiting production in many field crops. Several physical and chemical pretreatments are applied to the organic material (seeds/tubers) to overcome dormancy. Physical and physiological dormancy can be found together in some plants, and this makes it difficult to provide high-frequency, healthy seedling growth, since the formation of healthy seedlings from the organic material (seeds/tubers) sown is a prerequisite for plant production. This chapter will focus on the description of four different methods we have not seen reported elsewhere for overcoming dormancy.
Part of the book: Seed Biology
Yield in agricultural production decreases due to biotic (diseases and pests) and abiotic (salinity, drought, high temperature, etc.) stress factors. Chemical methods have been widely used to fight against biotic stress factors. However, the use of chemicals in agriculture causes extra financial cost and environmental pollution. Improvement of high yielded cultivars via plant breeding methods does not seem to be adequate for meeting food demand of increasing population. That is why, the improvement of environmentally friendly new methods for high yield is obligatory. Leaves in plants form an active surface for photosynthesis. High photosynthetic activity affects yield directly by increasing matter production. The aim of this study was to increase seed and oil yields in sunflower via leaf defoliation. Oil-type sunflower cultivars used in the study, “08-TR-003,” “TR-3080,” and “TARSAN-1018,” were obtained from the “Trakya Agricultural Research Institute.” When plants reached to “star-shaped head stage,” which is the beginning of the reproductive period, four different defoliation treatments were performed. They were control (no leaves removed), two leaves removed, four leaves removed, and six leaves removed. Half of the leaves were removed from just below the head, while the other half was removed from the middle part of the plant. After harvest, seed yield per plant, seed yield per decare, crude protein percentage, crude oil percentage, crude protein yield per decare, and crude oil yield per decare were determined. At the end of the study, it was observed that the application of defoliation, compared to the control, affected all characteristics positively.
Part of the book: Physical Methods for Stimulation of Plant and Mushroom Development