JOURNAL OF CROPS IMPROVEMENT (JOURNAL OF AGRICULTURE)
Year:2009 | Volume:11 | Issue:2|Papers Count:9

In order to evaluate salinity tolerance of six bread wheat varieties, an experiment was conducted during 2000-02 crop seasons in Roudasht Salinity Research Station, Esfahan. Effects of three levels of irrigation water salinities (four, eight and 12 dS m-1) were studied on six bread wheat cultivars including Pishtaz, Shiraz, Mahdavi, Marvdasht, Kavir and Roshan. Increase in salinity level of irrigation water caused significant decrease in grain yield, number of spikes per m2, days to physiological maturity, plant height and grain filling period. Among the varieties, Roshan and Shiraz had the minimum reduction percentage in grain yield in 12 dS m-1 compared to 4 dS m-1 In 12 dS m-1, Roshan and Shiraz produced 3987 and 3607 kg ha-1 grain yield, respectively and had the highest grain yield values among the varieties. Roshan also had the highest amounts of MP, GMP and STI (4257, 4248 and 1.20, respectively) and the lowest amounts of Tol and SSI (539 and 0.66, respectively), thus was the most tolerant cultivar to salinity among the studied cultivars. Based on the tolerance and susceptibility indices, Marvdasht was the most susceptible cultivar to salinity.

The performance of nine different linseed cultivars studied in a randomized complete block design (RCB) with four replications in Varamin region (Iran) in 2006. The traits were seed yield, fatty acids, protein and oil content of linseed. The difference between cultivars was significant for all traits (P< 0.01). The Legina cultivar had the highest seed yield (3000 kg/ha) and linolenic acid content (45.16 percent). The palmitic acid content of RH 14.05 cultivar, oil percent and stearic acid of GOLDA cultivar, and protein content and yield of native cultivar were higher than other cultivars (p≤0.05). The RH 14.05 cultivar which was low in linolenic acid and high in oleic acid can be used as a breeding line to produce oil.

The biology and phenology of broomrape (Orobanche nana) on Almond (Prunus dulcis cv. Mamaei) was studied during the growth season in Shahrekord city of Iran in 2004 twenty trees which were infested by broomrape, were selected. Results indicated that almonds need 2120.5 growth degree days (GDD) to complete phenological stages from flowering to fruit ripening. Based on the cardinal temperature of broomrape (9.5oC), the parasite weed needs 209, 1125.5, 1414.5 and 961 GDD for completion of seed germination, stem emergence, flowering and seeding stages, respectively. Maximum seed germination occurred at the depth of 18 cm. Maximum root infection was observed at the depth of 9 to 12 cm. The highest infection to this parasite plant was recorded on roots with 9 to 11.9 mm diameter.

In order to study the effect of drought stress in terminal growth period on agronomical and physiological characteristics of canola (Brassica napus L.) cultivars, a field experiment was conducted using split-plot layout based on randomized complete blocks design with four replications at experimental field of Seed and Plant Improvement Institute, Karaj in 2006. There were two factors, including irrigation at two levels (irrigation after 80 mm evaporation from class “A” pan as control and drought stress from flowering stage until physiological maturity) as main plots. In addition, twelve spring cultivars: (RGS003, Sarigol, Hyola401, Hyola 60, Hyola 330, Kimberly, 19-H, PR-401.16, PP-308.8, ORS 3150-3006, RG 4403, and RGAS 0324 )were applied in sub plots. Results showed that RG 4403 had maximum grain yield (3228 Kg/ha) and harvest index (29.9%). In drought stress conditions, best cultivar in grain yield, 1000-seeds weight and oil yield was 19-H and with comparison of stress tolerance indices had better compatibility to water stress. Sarigol and Hyola330 had the lowest yield and yield components and ORS3150-3006 was the most sensitive to water stress.

Nitrogen foliar spray is one of the most important components in fertilizing programs for citrus in Iran, as it can reduce nitrate leaching. The goal of this research was to determine the most effective concentration of foliar urea application on “Thamson Navel’’ orange trees, for achieving the highest yield. Foliar sprays were carried out, in two stages with total concentrations of 0.4, 0.8 and 1.2%. The first stage applied in April with concentrations of (0.25, 0.5 and 0.75%) and second stage in the end of July with concentrations of (0.15, 0.35 and 0.45%). Results of statistical analysis showed that urea treatment at concentration of 1.2% had significant effect on increasing the mean fruit weight. Also significant increase in mean fruit diameter and total soluble solids to acidity ratio in urea treatment at 0.4% concentration were observed. The results indicated that, there is no significant effect on vitamin C and ratio of fruit length to fruit diameter in urea treatment at concentration of 1.2%. All spray treatments increased fruit set. Finally, urea treatment at concentration of 1.2% had the best effects on more of studied traits.

Photosynthesis, stomatal conductance and leaf water potential characteristics were examined in two plantago species (Plantago ovata Forssk and P. psyllium L.), with gradually improving water stress for several days and permitting to recover by re-watering (withholding for 2, 4, 6, 8 and 10 days) in Melbourne University in 2006. Factorial experiments based on completely randomized design with four replications were used. The photosynthetic rate and stomatal conductance decreased rapidly by withholding water. After re-watering the recovery rate of photosynthesis and stomatal conductance decreased gradually, as the days became longer. The different rates of recovery of photosynthesis and stomatal conductance followed by drought stress. However, the potentional of photosynthesis recovery was more than stomatal conductance. It is also concluded that French psyllium had higher mesophyl and stomatal conductance recovery when compared to Isabgul, although recovery of photosynthesis in Isabgul was higher than French psyllium. The results showed a clear and close correlation between leaf water potential and recovery level of photosynthesis rate and stomatal conductance. A close correlation was also observed between photosynthesis and leaf water potential, stomatal conductance and relative water content.

A study was conducted on six years old trees of almond, Shahroud cv. (No. 18), in a three-year trial (2002-04) at Mashhad Agricultural Research Station. The experiment was done on the basis of completely randomized desigh with four replications. In the first and second years of the experiment, ethephon was sprayed in 15 and 20 days before the common time of harvesting, respectively. The concentrations of ethephon in 2002 were variable between zero to 600 mg/l; whereas in 2003, they were 0 upto 900 mg/l. Through 2003 and 2004, ethephon spraying (900 mg/l) was carried out in mid fall every year, too. A Khorasanina cultivar (named as No. 1) was also considered for fall treatment. In each year, the percentage of fruits with dehiscent hull increased by higher concentrations of ethephon, significantly. The forces (gravitometer figures) over which fruits have been detached from branches decreased significantly by higher concentrations of ethephon. We concluded that, the concentration of ethephon should at least be 500-600 mg/l so that the required results in ripening of almond fruits can be obtained. In order to delay the flowering time, ethephan spraying (900 mg/l) was the most effective treatment, in mid fall, considerably. In the case of summer treatments trees showed gummosis, mostley.

The effect of harvesting time on seed germination and seedling growth of six rapeseed (Brassica napus L.) cultivars were evaluated in field and laboratory in 2004-05 the experiment was conducted in a complete randomized block design based on split plot layout with four replications. The seeds of rapeseed cultivars were harvested based on grain moisture content of the siliques of one third of the bottom main stem; 1 )40% and higher, 2) 30-40% and 3) 20-30%. Standard germination test was conducted in a complete randomized block design based on split plot layout with three replications. Germinated seeds were counted daily for 7 days and germination indices were measured. Total germination, vigor index, germination index, germination rate, energy of germination and mean germination time were significantly different in harvesting times. All seed germination and seedling growth indices were higher in the third harvest and Hyola401 performed better germination indices.

In order to investigate the residual effect of different tobacco cultivars on germination and seedling growth of rapeseed, an experiment was conducted at laboratory and glasshouse during 2007 as factorial based on completely randomized design with four replications. Extracts of root and shoot from two different types of tobacco (Virginia and Basma) and different concentrations of extracts (0, 40 and 80%) were the treatments. Results showed that germination percentage and rate, shoot and root length in rapeseed (Hayola 401) in laboratory experiment and root and shoot length and ratio, shoot to root dry weight ratio, leaf area, seedling emergence and vigor and chlorophyll contents were significantly affected by different tobacco root and shoot extracts. According to results root extract of Virginia and shoot extract of Basma had the highest and the lowest effect in terms of mentioned traits, respectively. In glasshouse conditions extract concentration of 80% from Basma root and 40 and 80% concentrations from Virginia shoot caused the most reduction in shoot length of rapeseed. Among studied characters, germination rate had highly correlation with germination percentage and seedling vigor.