جستجوی مقالات مرتبط با کلیدواژه "normal seedling" در نشریات گروه "زراعت"

Drought stress, as abiotic and multidimensional stress, has severe effects on plant growth. One of the new approaches in the management of drought stress is the use of nanoparticles. Nanoparticles infilterate the seeds and increase nutrient and water uptake and ultimately, improve germination. The present research was conducted to evaluate the effects of titanium dioxide nanoparticles on chickpea plant germination factors to modify the negative effects of drought stress.

A factorial experiment was conducted in a completely randomized design with four replications on chickpea seeds of Arman cultivar in the Plant Sciences Research Institute of the Ferdowsi University of Mashhad in 2019. Seeds were primed with concentrations of 0, 5, 10, 15, and 20 mg L-1 titanium dioxide for 24 hours. The seeds were cultured in sterilized Petri dishes. Drought stress was applied using polyethylene glycol 6000 with 0, -2, -4 and -8 bar osmotic potentials.

The analysis of variance results showed that the interaction effect of drought stress and titanium dioxide nanoparticles was significant on germination rate, the number of normal seedlings, seed vigor index, germination index, length of seedling, radicle length, and radicle dry weight. All germination traits were inhibited as a result of drought stress. On the other hand, the presence of titanium dioxide nanoparticles partially decreased this inhibition in some traits. Germination percentage, germination rate, normal seedling percentage, seed vigor index, germination index, epicotyl length, radicle length and radicle dry weight decreased as a result of stress.

At all drought stress levels, the concentration of titanium dioxide nanoparticles up to 20 mg L-1 significantly improved traits such as germination percentage, seed vigor index, epicotyl length, and epicotyl dry weight. It seems that nanoparticles can stimulate cell activity and increase the transformation of reserves to translocatable material and consequently, improve germination characteristics. Thus, the application of titanium dioxide nanoparticles up to a concentration of 20 mg L-1 can partially reduce the negative effects of drought stress on the germination characteristics of chickpeas.

To evaluate the quality of fields and seed plots in two wheat seed production companies in Tehran (1) and Alborz (2) provinces. The experiment was conducted in 2018-2019 on Sirwan, Baharan, Sivand, Pishtaz, Rakhshan, Pishgam, and Persian gold cultivars at Seed and plant Certification and Registration Research Institute according to PROJECT NO: 2-08-08-021-971216. The distribution of noxious weeds, other crops, and other species in fields was recorded. Also, seed samples were analyzed in a seed quality analysis laboratory for seed germination percent and physical purity. The results showed that the fields of company 2 were better than company 1. As a result, the number of other crops in fields of companies 2 and 1 were observed at 1.1 and 2.2, respectively. Also, the number of other species in fields was recorded for companies 2 and 1, 9.1 and 9.9, respectively. The most weeds that have been observed in fields and seed samples were Avena fatua L. In addition, 66.1% and 39.2% of total Avena fatua L. were related to companies 1 and 2, respectively. Meanwhile, according to the estimated seed sample for the number of noxious weeds and other crops before processing, seed production of company 2 was better than company 1. Also, wheat seed yields for the two companies were recorded at 5.0 and 4.6 tons per hectare, respectively. The physical purity was 99.6% in the two companies, but the normal seedling of companies 2 and 1 was 93.9% and  93.6%, respectively.

The objective of this study was to evaluate the effects of sowing and picking dates on lint yield and its component, germination and seed vigor of Varamin cultivar of cotton. To this end, experiments were carried out as split-plot in time based on randomized complete block design with three replications at the cotton fields of Kizor in Sabzvar in 2013. Treatments were four sowing dates (May 8, May 20, Jun 2 and Jun 14 of 2013) and two picking dates (the harvest date of first picking for first to fourth planting dates were September23, September29, October 14 and October 27. The harvest dates of second picking for first to fourth planting dates were October 7, October 12, October 24 and November 11). Standard germination and cool germination tests for different temperatures were also performed. 1000-seed weight, number of normal seedlings and dry weight of normal seedlings were measured. Results showed that the effect of planting date, picking and their interaction effects on lint yield, seed thousand weight, number of bolls per plant, single plant weight, number of normal seedlings, dry weight of normal seedlings, germination percent, lint length and electrical conductivity were found to be significant. Highest (3693.3 kg.ha-1) and lowest (1023.00 kg.ha-1) lint yields obtained from the first picking of first planting and second picking of fourth planting, respectively. The number of normal seedlings and dry weight of normal seedlings didn’t follow a special process in standard germination test, but the number of normal seedlings produced from cool germination test of first picking with delay in sowing date was decreased in a linear form. The number of normal seedlings from alternate temperatures (one week in 18°C and the other week in 28°C) “except the first sowing date” was decreased. Results showed that by delaying sowing date (at the range of this study) seed vigor decreased. According to the results of this research, the first planting date (May 8) could be recommeded for growing Varamin cultivar for higher lint yield to this region. But, for seed production, the first picking of second planting date (May 20) is recommended.

Almolookhiyeh (Corchorus olitorius L.) known in the world as a valuable medicinal plant that was produced for the first time in Iran in 2011. This study was aimed to quantify germination response of Almolookhiyeh to temperature. For this purpose، seeds were exposed to different constant temperatures (10، 15، 20، 25، 30، 35، 40، 45 and 50°C) in Seed Research Lab، Gorgan University of Agricultural Sciences and Natural Resources in 2011. Results showed that the effect of temperature on the maximum germination percentage (MGP)، germination rate (R50)، germination uniformity (GU)، and time to 10، 50 and 90 percent germination as (D10)، (D50) and (D90)، the percentage of normal seedlings (NS%) and seedling length (LS) was highly significant. Assessment of three nonlinear regression models including segmented، dent-like and beta models based on 10، 50 and 90 percent germination revealed that beta model was superior to other models. Based on the superior model (Beta)، base، optimum and ceiling temperatures were estimated as 10. 18، 37. 31 and 50°C، respectively. Biological hours also were calculated as 13. 56 hours. Using beta model to regress seedling length against temperature and normal seedling percentage versus temperature showed that seedling emergence، the maximum seedling length and the highest normal seedling percentage were occurred at 11 to 44، 35. 34 and 31°C، respectively.