مجله تولید گیاهان زراعی
سال یکم شماره 3 (پاییز 1387)

In order to investigate the effect of nitrogen fertilizer rates and top dressed on nitrogen remobilization in different rice cultivars, a field experiment was conducted in the Rice Research Institute of Iran (Amol) during 2006. A split split experiment in the basis of randomized complete block design with 3 replications and 3 factors were used in which fertilizer rates in 3 levels (including 46, 69 and 92 kg N ha1 from urea source), top dressed in the 3 levels (in variable ratios in transplanting, tillering and heading stages including S1(50, 25 and 25 percentage) S2 (25, 50 and 25 percentage) and S3 (25, 25 and 50 percentage)) and cultivar in 3 levels (including Tarom, Shafagh and Bahar 1) were considered as main plot, sub plot and sub sub plot, respectively. Results of variance analysis showed that cultivars and different organs of plant had different responses to nitrogen fertilizer rates and split application in terms of nitrogen remobilization, and traditional cultivar, Tarom, had the highest amount of nitrogen remobilization from shoot organs. Among nitrogen fertilizer levels, 69 kg.ha-1 caused the highest rate of nitrogen remobilization, although application of the second split application level (S2) (25, 50 and 25 percentage) increased this rate too. Moreover, Tarom cultivar had the highest rate of nitrogen remobilization from stem and other leaves that seems due to early maturity and increased senescence of leaves in this cultivar. Findings of this experiment showed that nitrogen remobilization had a significant and positive correlation with grain yield. Among shoot organs, stem nitrogen remobilization had the highest significant and positive correlation(r=0.65**) with grain yield.

This experiment was conducted to quantify leaf production and senescence in wheat. The experiment was carried out at Research farm of the Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran in 2005 using a Randomized Complete Design considering sowing dates as environment. Treatments were sowing date (14 December, 20 Jan and 21 Feb, 2005) and cultivars (Aria, Atrak, Koohdasht, Shirodi, Tajan, Taro and Zagros). The results revealed that the start of leaf production, leaf appearance rate and time of cessation of leaf production on main steam arent different in between cultivars but leaf production rate on main steam for sowing dates was 0.01 leaf day-1. Leaf senescence on main steam commenced after 475 growth degree day (GDD) and it continued at 0.07% per GDD. Production of leaves in plant consisted of two phases and that were closely related to the leaf production on main stem. At the first phase, one leaf were added to the whole plant leaves by each leaf increase on the main stem. The second phase started when there were three leaves on main stem. At this phase, 2.7 leaves were added to the leaves of the whole plant by each leaf increase on main stem. Leaf death on whole plant was closely related to leaf senescence on the main stem, and it had two phases. With each percent of leaves death on main stem 0.83 and 1.03 percent of whole plant leaves died at first and second phases, respectively. Mean leaf longevity was about 616 GDD. The results suggest that leaf production and senescence in wheat could be quantified using different equations.

In order to evaluation rice cultivars in different irrigation treatment based on sensitive and tolerance indices in rice, an experiment was conducted as split plot based on Randomized Completed Block Design with three replications at Rice Research Institute of Iran. Main factors were included of five irrigation levels: flooded irrigation (normal treatment), irrigation after banishment, five, eight and eleven interval irrigation (stress treatments) and sub main factors were included three verities: Bhar, Dorfak and Ali kazemi. Mean of yield and panicle number of plant showed that Bahar is the most tolerant variety because of its the most panicle number in plant. Data showed highest HM, STI, GMP and MP indices and least SSI and TOL for all traits and irrigation levels for Bahar. The result of this research showed that for selection of the best Iranian rice variety and determination of best irrigation management based on yield can use these tolerant and sensitive indices in different irrigation position.

The main objective of this study was to understand of genetic association between quantitative and qualitative traits and also to quantify effects of selection for one trait on others in safflower. The study took place in the experimental field of the faculty of agriculture, Isfahan University of Technology, Isfahan, Iran, in the 2001 and 2002. To find the best variable for selection to improve evaluated traits the correlated response to selection was calculated. The correlated response to selection indicates when selection takes place for a trait what happens for other related traits. The results indicated that, among all correlated traits with seed yield per plant the highest progress can be obtained by selection for increasing the number of head per plant, because correlated response to selection for number of head per plant was bigger than others. After the number of head per plant, the most important trait for improving of seed yield was number of seed per head. Also, if shortening of time to maturity be the aim of breeding project, the best choice is selection of dwarf genotypes, because the highest increasing of correlated response to selection was observed for plant height. On the results of this study it was proposed that evaluation of casual association between yield components and designing of ideotype in safflower must be done with considering of genetic correlations between all related traits and for selection of one trait much attention should be pay to its correlations with other traits. Our findings shows that increasing the number of head per plant improve seed yield and additionally decrease number of seed per head, and this can reduce amount of yield improving. Therefore, it seems necessary that for improving seed yield in safflower a suitable selection index would be defined. Plant height was the best variable for increasing oil content in indirect selection, because the results showed that its correlated response to selection was higher than other traits.

Evaluation of soil microorganisms and their beneficial relationships among ecosystem components is one of new topic in soil resource management for ensuring sustainable agriculture. In order to investigating effects of Trichoderma spp. and different organic manures on improvement of growth and development in soybean [Glycine max (L.) Merril.], an experiment was conducted at glasshouse in Sari Agricultural and Natural Resources Sciences University. The pot experiment was laid out factorial based on completely randomized design with four replications. Four seedbed materials [consisted of field soil as control, vermicompost and municipal waste compost (20 ton/ha) and farmyard manure (30 ton/ha)] and two species of Trichoderma (including T. harzianum and T. viridae) with a check were the treatments. Results showed that application of vermicompost, compost and farmyard manure enriched with T. viridae increased soybean root weight as much as 19.6, 37.7 and 18.3 percent, respectively. Inoculation of two fungi with farmyard manure and compost significantly increased shoot and plumelet weight. Furthermore, application of two fungi with farmyard manure and compost simultaneously increase seedling emergence percent compared to control. However, only T. harzianum and compost combination had additive effect in terms of final emergence percent. Overall, inoculation of T. harzianum could improve cumulating emergence rate (CER) compared to control.

In order to evaluate of drought tolerance in different Canola varieties based on stress evaluation indices in terminal growth duration, an experiment was conducted as split-plot design on randomized complete block design with four replications at experimental field of Seed and Plant Improvement Institute, Karaj in 2005 and 2006. Results using Stress Susceptibility Index (SSI) and Tolerance Index (TOL) revealed that Talaye and Opera varieties are more tolerant than other varieties. Stress Tolerant Index (STI) and Geometric Mean Productivity (GMP), that their higher values indicate the tolerance of cultivars under stress, revealed Opera, Hyola420 and Zarfam, as cultivars with highest yield in both optimum irrigation and drought conditions. Study of total indices with give attention to that the best cultivars are they have high yield in optimal condition and least decrease in yield at stress condition, introduced Opera and Zarfam cultivars as suitable cultivars in drought stress condition. Study of high and positive correlation between drought tolerance index (STI), Geometric mean productivity index (GMP) and mean productivity index (MP) with yield in optimum and drought conditions indicated that them as the best indices for introduce drought tolerant cultivars.