Ramazan Beyaz

By Mustafa Yildiz, Emine Selcen Darcin and Ramazan Beyaz

Plants could be propagated vegetatively via small parts of living tissue called as ‘explant’ on growth mediums under sterile conditions. Plant cell has the ability of forming whole fertile plant which is called 'totipotency', under in vitro culture conditions. High-frequency shoot regeneration is one of the main aims of in vitro culture and it is a prerequisite to guarantee the success in transformation studies and in clonal propagation of plants. It is well known that growth regulators in culture medium and the type of explant affect in vitro regeneration frequency significantly. In this chapter, the importance of tissue water content on in vitro culture response is discussed. Increasing water content of the explant before culture initiation gives rise to increased regeneration capacity. On the other hand, increasing the tissue’s osmotic pressure enables the explant to intake water, all solutes and growth regulators from the growth medium which results in high-frequency shoot regeneration. However, tissues with lack of water are usually not successful in regenerating a satisfactory amount of shoots. The effect of water deficiency on explant’s regeneration capacity and the methods to overcome this problem are discussed in this chapter.

Part of the book: Water Stress in Plants

By Ramazan Beyaz and Mustafa Yildiz

In plant breeding programs, one of the oldest methods is mutation breeding. Currently, mutation breeding has became popular among the breeders and scientists again with its use in plant biotechnology and due to some restrictions on the other techniques such as hybridization, cross breeding, and transgenic plants. Physical mutagens (X-rays, UV light, neutrons-alpha-beta particles, fast and thermal neutrons, especially gamma rays) are used more widely than chemical (ethyl methanesulfonate [EMS]) ones to artificially induce mutations (mutagenesis). However, among the physical mutagens, gamma-rays are widely used. During the irradiation of the seeds with ionizing radiation to generate mutants with desirable traits, reactive oxygen species (ROS) or free radicals can generate in cells. Although, these radicals/species generally can be very dangerous for the cell compartments, they can take an important role as a signal molecule activation of genes of antioxidant enzymes and proline, which are defense systems against these radicals in plant cells. In this chapter, usability of gamma-irradiation to provide the permanent gene expression of antioxidant enzymes and proline through the production of reactive oxygen species (ROS) is discussed.

Part of the book: Plant Engineering

By Mustafa Yildiz, Ramazan Beyaz, Mehtap Gursoy, Murat Aycan, Yusuf Koc and Mustafa Kayan

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

By Mustafa Yildiz, Mehdi Taher, Marieh Javani, Ramazan Beyaz and Mehtap Gursoy

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

By Mustafa Yildiz, İrem Poyraz, Aslinur Çavdar, Yasin Özgen and Ramazan Beyaz

Salt stress is one of the harmful abiotic stress factors. It makes agricultural lands especially in arid and semi-arid regions useless despite the efforts. More than six percent of total world agricultural lands are on the edge of vanishing due to salt stress. Salinity in soil occurs as a result of the factors such as lack of drainage, improper irrigation, excessive accumulation of soluble salts. Salinity limits the growth of plants. Despite the main results, some results of plants due to these limitations vary from species to species. The negative effects get morphological, biochemical and physiological reactions from plants. Slowed or stopped growth of roots and shoots, closuring of stomata, germination slowing, decreased or stopped development of seedling, deterioration of photosynthetic activity are the main reactions of plants to stress. On the other hand, plants also develop tolerance mechanisms as a result of some auxiliaries for surviving under adverse conditions. Plants have tendency to protect themselves from salinity with osmotic protectants synthesized by them such as sugars, proline, amino acids, glycine betaine. In this review, the responses of plants to salt stress were investigated and gathered.

Part of the book: Plant Breeding