Enhancement of IBA stimulatory effect on rooting of olive cultivar stem cuttings
Three groups of olive cultivars were characterized as showing low, moderate or high rooting percentage after application of indole-3-butyric acid (IBA) treatment. To improve the rooting of olive cuttings, urea-phosphate (UP) and paclobutrazol (PB) were tested in combination with IBA. UP alone did not stimulate rooting of olive cuttings; however, when applied together with IBA it significantly enhanced the rooting of cultivar ‘Manzanillo’ cuttings. PB alone had a weak effect on rooting of cuttings but in combination with IBA it improved the rooting of cultivars ‘Manzanillo’ and ‘Souri’ cuttings. A triple combination of IBA, UP and PB provided the most effective treatment for the improvement of rooting percentage. IBA treatments increased the number of roots per cutting in comparison with the control, but decreased the length of the roots of cultivar ‘Barnea’. IBA plus UP or PB further increased the number of newly formed roots. However, IBA plus UP markedly increased root length. The three compound treatment did not differ from IBA plus PB regarding root number per cutting, but the roots were longer than in IBA treated and control cuttings. The survival of rooted cuttings treated with IBA was relatively low, for all cultivars tested. IBA plus UP plus PB improved the survival of the rooted olive plants compared with IBA alone. Thus UP and PB were shown to enhance the effect of IBA in stimulation of rooting and survival of olive cuttings. [1]
Rooting of stem cuttings of Eucalyptus: A rooting inhibitor in adult tissue
The available physiological evidence suggests that ontogenetic ageing of E. Grandis seedlings involves a direct and quantitative association between decreased rooting ability of stem cuttings and increased levels of a rooting inhibitor in the tissue forming the base of the cutting. As detected by bioassay, this inhibitor is present only in adult tissue, which very rarely forms roots from stem cuttings. It is absent in easily rooted seedling stems of all Eucalyptus species tested, but it is also absent in the easily rooted adult tissue of the exceptional species E. deglupta. The ability of seedling cuttings of E. deglupta to root very easily in water provides an appropriate bioassay for monitoring the presence of inhibitor in other Eucalyptus species. [2]
Vegetative propagation ofDalbergia sissooRoxb. using softwood and hardwood stem cuttings
Mature hardwood and softwood cuttings ofDalbergia sissooRoxb. were tested for their ability to root. Cuttings were prepared in three different seasons, i.e. spring, monsoon and winter, and treated with different concentrations of auxins (IBA and NAA). These were planted in a mist chamber maintained at 30 ± 2°C. Both types of cuttings rooted during spring and monsoon seasons. Auxins triggered/enhanced rooting of cuttings; NAA (100 mg l−1) and IBA (100 mg l−1) were found to be the most effective. Higher concentrations of auxins, i.e. 500 and 1000 mg l−1of IBA and NAA, in general inhibited or slowed down the rooting ability of cuttings. Auxin appears to trigger both growth and differentiation of roots since auxin-treated cuttings which rooted had a greater number as well as increased length of roots. The starch content of cuttings decreased while proteins and sugars increased with time. [3]
Effects of Different Auxin (IBA) Concentrations and Planting-Beds on Rooting Grape Cuttings (Vitis vinifera)
Aims: Vitis vinifera is a grape species and native to the Mediterranean region and east to northern Iran. The present research was carried out in greenhouse conditions to study the effects of four concentrations of indole-3-butyric acid (IBA) (0; 2000; 4000; and 6000 mg/l) and three planting beds (agricultural soils, sandy, and mixture of agricultural soils and sand) on rooting grape cuttings in institute of agriculture at Zabol University, (Iran).
Methodology: The experimental design was a factorial design in randomized complete block with three replicates.
Results: Results showed that different auxin and planting bed treatments had a significant influence on grape rooting. The maximum number of roots, root length, and root fresh and dry weight was obtained by applying 4000 mg/l IBA. The significant effect of planting bed treatments was found in studying traits, so that maximum number of roots, root length, and root fresh and dry weight was obtained in mixture of agricultural soils and sand planting beds. Studied traits significantly affected by an interaction effect of IBA and cuttings beds, so that maximum number of roots, root length, and root dry weight was obtained by using 2000 mg/l IBA + sandy planting bed, and maximum root fresh weight was obtained by using 4000 mg/l IBA + sandy planting bed. [4]
Role of Mutation Breeding in Crop Improvement- Past, Present and Future
With the inevitable risk posed by global climate change to crop yield and ever increasing demands of agricultural production, crop improvement techniques have to be more precise in developing smart crop varieties. This review reviews the past, current progress and assesses the future directions in mutation breeding for crop improvement. It provides a background to plant mutation breeding strategies, basic and advanced techniques, and provides a critical review of this approach in comparison to other methods for the genetic improvement of crops. Mutation breeding is a fundamental and highly successful tool in the global efforts of agriculture to feed an ever increasing and nutritionally demanding human population. The physical and chemical mutagens, their effects and their utility are discussed. The induction of mutations has been used to enhance the yield, better nutritional quality and wider adaptability of world’s most important crops such as wheat, rice, pulses, millets and oilseeds. The total area covered by commercially released mutant cultivars clearly indicates that they have played a significant role in solving food and nutritional security problems in many countries. Of all the mutant varieties developed, majority of mutants were produced through direct mutagenesis of the plant propagules, and also there are several reports of mutants derived by irradiating rooted stem cuttings, which paves the way for in vitro mutagenesis. The production of mutants by irradiation of in vitro cultured tissues provides a means to treat large populations which would not have been possible before. The accessibility of genomics information in the public domain combined with the recent advances in molecular biology techniques have paved the way for transforming old mutation techniques into the state of art technology for crop improvement and basic genomic research. The molecular tagging and molecular marker based identification shall bring new dimensions in gene technology. These would finally lead to rapid enhancement of crops with improved yield, increased biotic and abiotic stress and reduced agronomic inputs. Thus mutation assisted plant breeding will play a crucial role in the generation of designer crop varieties to address the threats of global climate change and challenges of world food insecurity.[5]
Reference
[1] Wiesman, Z. and Lavee, S., 1995. Enhancement of IBA stimulatory effect on rooting of olive cultivar stem cuttings. Scientia Horticulturae, 62(3), pp.189-198.
[2] Paton, D.M., Willing, R.R., Nicholls, W. and Pryor, L.D., 1970. Rooting of stem cuttings of Eucalyptus: a rooting inhibitor in adult tissue. Australian Journal of Botany, 18(2), pp.175-183.
[3] Puri, S. and Verma, R.C., 1996. Vegetative propagation ofDalbergia sissooRoxb. using softwood and hardwood stem cuttings. Journal of arid environments, 34(2), pp.235-245.
[4] Galavi, M., Karimian, M.A. and Mousavi, S.R., 2013. Effects of different auxin (IBA) concentrations and planting-beds on rooting grape cuttings (Vitis vinifera). Annual Research & Review in Biology, pp.517-523.
[5] Raina, A., Laskar, R.A., Khursheed, S., Amin, R., Tantray, Y.R., Parveen, K. and Khan, S., 2016. Role of mutation breeding in crop improvement-past, present and future. Asian Research Journal of Agriculture, pp.1-13.
