A Habashi, A Mousavi, M Kaviani, S Khoshkam, A Rostami,
Volume 12, Issue 46 (fall 2009)
Abstract
Date palm (Phoenix dactylifera L.) is propagated traditionally through offshoots or suckers, which usually appear at or below the ground level surrounding the stem base. However, there are many problems associated with this system. Offshoots are produced in limited number and vegetative propagation through them is slow, laborious, time consuming and expensive. The present study was conducted to determine the best micropropagation protocol for date palm in Kebab, Estameran, Piarom, and Berehi cultivars. The shoot apical meristem from two to three-year-old offshoots was used as source of explants. They were cultured in callus initiation medium, containing different concentrations of 2,4-D (40, 60, 80 and 100 mgl-1), NAA (10 and 20 mgl-1) and 2ip (3 and 5 mgl-1). All cultivars produced high percentage of callus with good quality in a matter of callus friability and color in 100 mgL-1 2,4-D, 20 mgL-1 NAA, and 3 mgL-1 2ip. Kabkab cultivar was superior for callus production (87.25%) in comparison with other cultivars. The calli were then transferred to a proliferation medium and then transferred to somatic embryogenesis medium containing different concentrations of Kinetin (2, 4 and 6 mgL-1), BAP (2, 4 and 6 mgL-1), and NAA (0.1, 0.5 and 1 mgL-1). Somatic embryogenesis was observed in MS medium supplemented with 2 mgL-1 kinetin, 2 mgL-1 BAP, and 0.1 mgL-1 NAA. Kabkab and Estameran cultivars showed higher somatic embryogenesis in comparison with other two cultivars. The somatic embryos were then transferred to MS medium without hormones under light, where they produced shoots and roots. Abbriviations: 2,4-D- 2,4-dichlorophenoxiaceticacid 2ip-N6(2-isopentenyl)adenine NAA-Naphthalene acetic Acid BAP-6-Benzylaminopurine MS-Murashige and skoog (1962).
F. Safari, H. Ramezani Etedali, A. Kaviani, L. Khosravi,
Volume 28, Issue 4 (Winter 2025)
Abstract
Climatic factors play an important role in the growth and development of plants and affect agriculture. The tolerance threshold of plants for each of these factors is limited. Any change in these factors can directly and indirectly have significant effects on agricultural production. Meanwhile, temperature stress is one of the most important damaging phenomena that causes many problems for production and yield. In this research, the time of occurrence of temperature stress with a statistical period of 44 years (1980-2023) and the relationship between air temperature with yield and biomass were investigated. According to meteorological data, June, July, and August were known as the hottest months of the year. On the other hand, the most heat waves were observed in July and August in the years 1997, 2014, and 2018, which led to a decrease in the quality of the product or the loss of the plant. According to the model evaluation results, the accuracy of the model in simulating days to flowering and days to maturity was confirmed using R2 (0.8 and 0.51) and NRMSE (15.36 and 7.12). Also, the model was simulated for the studied fields with deviation percentages of 1.92, 5.65, 4.94, 1.58, 0.96, and 1.49%, respectively. It showed that the model had a satisfactory performance and could be used for maize production planning. Next, the relationship between temperature, yield, and biomass was investigated, and there was a negative and significant relationship between temperature, yield, and biomass at the 99% confidence level.
