Showing 5 results for Growth.
Y. Fathipour, A. Hosseini, A. A. Talebi, S. Moharramipour, Sh. Asgari,
Volume 9, Issue 2 (7-2005)
Abstract
The biological parameters of cabbage aphid, Brevicoryne brassicae (L.) was studied in the laboratory conditions under the three constant temperatures (20, 25 and 30 ºC), RH 60±5% and a photoperiod of 16:8 (L:D) using 40 first instar nymphs. Among nymphs, 40%, 55% and 10% of them completed their nymphal period in 20, 25 and 30 ºC, respectively and developed to adult stage. In 30 ºC, the most biological acitivities of aphid were disrupted and the most individuals (nymphs and adults) were killed. Most developmental periods, longevity and the amount of reproduction in 20 ºC were significantly greater than other temperatures. In temperatures 20, 25 and 30 ºC the last individual of a cohort died in age of 33, 29 and 16 days, respectively. The life expectancy of cabbage aphid in the first day of experiment was 13.93, 10.50 and 7.19, respectively according to the mentioned temperatures. There was a little difference between net reproduction rates in temperatures 20 and 25 ºC (16.74 and 15.92, respectively). Net reproduction rate was reduced extremely in temperature 30 ºC (1.75). The intrinsic rate of the increase in the temperatures 20, 25 and 30 ºC were 0.187, 0.226 and 0.042, respectively. The results indicated that 25 ºC was the optimal temperature for biological activities of B. brassicae and its highest population growth was observed at this temperature.
M. Haghighat Afshar, M. Babalar, A. Kashi, A. Ebadi, M. A. Asgari,
Volume 10, Issue 3 (10-2006)
Abstract
Some strawberriy cultivars (Fragaria x ananassa Dutch. cv. Aliso, Selva, Gaviota and Camarosa) were grown hydroponically with five NH4:NO3 mM concentration ratios (0/6 (S1), 0.25/6 (S2), 0.5/6 (S3), 1/6 (S4), 2/6 (S5) and constant nitrate concentration in three replicates for two seasons: Summer and Winter, in greenhouses of Agriculture Faculty of Tehran University. The results are reported as Follows: In summer shoot dry weight and shoot/ root ratio were highest in 0.25 and 0.5 mM NH4-N and were constant in remaining solutions with higher ammonium concentration. Increasing ammonium concentration resulted in decreasing the root dry weight. Aliso and Selva had the highest shoot and root dry matter respectively. Gaviota had the highest runner. In winter, shoot dry matter was highest in plants grown in S5 solution. Increasing ammonium from 0 to 0.5 mM decreased fruit yield but more ammonium in S4 and S5 solution increased yield. Root and fruit dry matter were highest in Selva. Yield and Fruit fresh weight were highest in Gaviota. Camarosa had the highest shoot dry weight. In summer shoot dry weight was significantly higher than in winter. Due to the high yeild, commercial use of the S5 solution and the cv. Gaviota is recommended.
S. Eshghi, E. Tafazoli,
Volume 10, Issue 4 (1-2007)
Abstract
Today, the production of disease-free and identical rootstock seedling in protected environments is a common practice in citrus industry. The process is time consuming, laborious and expensive. Shortening the period to reach suitable size for budding results in the reduction of the costs. It is possible to shorten the period for budding in citrus seedlings through the application of growth regulators. As lime is used widely as a rootstock in Southern Iran, this research attempted to study the effect of paclobutrozol (PP333), ethephon and pinching following gibberellic acid (GA3) treatment on height, diameter and budtake of lime seedlings. To do the research, seedlings with 4-6 leaves were sprayed with 100 mg/L GA3. After GA3 treatment, uniform seedlings 50 cm height were selected, potted and sprayed with PP333 (500 and 1000 mg/L), ethephon (150 and 300 mg/L) or pinched. All treatments, compared with control, increased height, diameter and fresh weight of shoot significantly. GA3 alone caused internode elongation. The effect of all treatments on the number of node, fresh and dry weights of root was not significant. Ethephon reduced chlorophyll content of leaf. And ethephon (300 mg/L) and PP333 (1000 mg/L) reduced budtake percentage of lime seedlings.
M. Hajghani, M. Saffari, A. A. Maghsoudi Moud,
Volume 12, Issue 45 (10-2008)
Abstract
Soil salinity is an increasing environmental stress on crops in most areas of Iran since farmers use underground saline water for irrigation. In order to investigate the effects of salt stress on germination and seedling growth of safflower (Carthamus tinctorius L.), an experiment was conducted at two stages (germination seedling growth), using four levels of NaCl salinity (0, 5, 10, 15 ds/m), and four cultivars of spiny and non-spiny safflower ( a landrace from Isfahan bred cultivars of IL, LRV and PI). The design was factorial and completely randomized based on 3- replicates (CRD). Germination percentage, germination velocity index, root and shoot length, root and shoot dry weight, root to shoot dry weight ratio and salt tolerance index were measured at germination stage. In seedling growth stage, traits such as, stem length, number of leaves, chlorophyll index, root and shoot dry weight, root to shoot dry weight ratio and salt tolerance index were also measured. Results for both growth stages showed that salt stress decreased all the above mentioned traits, significantly, in all cultivars. Salinity × variety interaction at germination stage was also significant, compared to seedling growth stage. Salt tolerance index decreased significantly with increasing salinity at both stages, but differences between cultivars were not significant. Cultivars PI and IL were characterized as the tolerant ones at germination and seedling growth stages, respectively. It could be concluded that safflower cultivars responded differently to salinity in germination phase compared to seedling growth phase, and that safflower suffers more from salinity during germination stage.
S. Eskandari , V. Mozafari,
Volume 16, Issue 60 (7-2012)
Abstract
A greenhouse experiment was conducted to study the effects of soil copper (Cu) and salinity on growth and chemical composition of two pistachio cultivars. A factorial experiment was carried out as a completely randomized design with three replications. Treatments consisted of four Cu levels (0, 2.5, 5, and 7.5 mg Kg-1soil as CuSO4.2H2O), five salinity levels (0, 800, 1600, 2400, and 3200 mg NaCl Kg-1 soil) and two pistachio cultivars (Badami-e-Zarand and Ghazvini). Results showed that salinity significantly decreased growth parameters. Application of 3200 mg NaCl Kg-1 soil decreased shoot and root dry weights, leaf area and stem height by 67, 72, 45 and 76 % respectively. Application of 7.5 mg Cu Kg-1 soil increased shoot dry weight and leaf area by 24 and 26% respectively. Morever, there was no significant difference between growth parameters of two pistachio cultivars, except for leaf area index. Salinity stress significantly decreased shoot and root P, k and Cu total uptake, and increased that of Na and Cl. Application of 5 mg Cu Kg-1 soil significantly increased shoot Cu uptake. Since total uptake of all elements for Badami cultivar was significantly higher than the Ghazvini, it could be concluded that the latter cultivar is probably more resistant to the saline conditions.
