پژوهشنامه اصلاح گیاهان زراعی
پیاپی 1 (بهار 1388)

Molecular markers are the best method for investigating the genetic diversity. In thisexperiment, 72 cultivars including Indica and Japonica were investigated in RiceResearch Centre of Iran. In order to evaluate the genetic diversity of locus waxy linkedto the trait controlling the amylose content, PCR was performed using twooligonucleotides (484 and 485) and scored. The important Iranian cultivars of rice werescreened using waxy microsatellite marker and classified into seven groups based on(CT)n repeats ranging from n=7 to 20. The amplified PCR products ranged from 102 to128 bps in length and represented the (CT)n repeats of (CT)7, (CT)8, (CT)14, (CT)17,(CT)18, (CT)19 and (CT)20, that were according to amylose content of cultivars in Iraniangermplasm classified in seven groups for that locus and explained 70%, 72%, 78.95%,80% and 70% of each group variations, respectively.

In order to evaluate the response of rice genotypes to salinity stress, 16 rice genotypeswere assessed to 4 salinity levels (0, 4, 8, 12, dS/m) through a split plot experiment basedon completely randomized design at germination stage. Germination percentage,germination rate, length of radicle, length of shoot, radicle dry weight, shoot dry weight,total biomass, and total radicle-shoot weight were measured. Results showed thosegermination percentage and germination rates were decreased by the increase of salinity. It was demonstrated that tolerant varieties had a more germinate. Salinity had a significanteffect on all of the studied traits expect total biomass. Germination rate showed significantcorrelations with germination percentage, radicle length, shoot length, and dry weights ofradicle and shoot (P≤0.01). Dry weight of shoot showed significant correlations withgermination percentage, radicle length and shoot length. Based on germination traits,PSBRC88 and IR58025A/IR60819R were determined as salt tolerant and sensitivevarieties, respectively. Results of this study would help to select for salt tolerant varieties in rice breeding programs.

The present study was aimed to screen the pectinase activity from some generaof Mocur in laboratory conditions. Pectin was used as the only carbon source in aminimal culture medium. Tow days after inoculation released proteins and sugarswere assayed with related reagents and repeated each 2 days up to 21th day.Statistical analysis showed significant variation in released sugars and releasedproteins among tested genera. Mucor hiemalis silvaticus had highest and Mucorcircinelloides janssenii had lowest sugar levels. Also Mucor circinelloidesf. lusitanicus had highest and Mucor plumbeus had lowest protein levels. Glucoseand protein levels for superior Species have increased until 15 and 13 days,respectively for glucose and protein after inoculation, then decreased until 25th day,but had no variation until 30th day. These results showed that isolates belong to thesame forms had no significance difference in pectinase activity.

In the area with terminal heat and drought stress such as Gonbad, allocation ofproduced dry matter to reproductive organs is of great importance. In order to evaluatethe effect of different temperature and moisture regimes on dry matter distribution andharvest index ofcanola an experiment wasconducted at Agricultural Research Station ofGonbad during 2005-2007. The experiment was a RCBD arranged in a split-plot intwoconditions, i.e. supplemental irrigation and rainfed. Five sowing dates (6 Nov., 6Dec., 4 Jan., 5 Feb. and 5 Mar.) were selected as main plots and tow cultivars(Hyola401 and RGS003) werechosen as subplots. In both years of the experiment, at thebeginning of seed filling period, the mean accumulated dry matter in reproductiveorgans, green leaves and stem at supplemental irrigation was more than that ofrainfedconditions. There was not any difference for stem accumulated dry matterbetween the beginning of flowering and seed filling. The considerable differencesbetween these two stages were a decrease in realative proportion of accumulated drymatter in green leaves and an increase in accumulated dry matter in reproductive organs.Supplemental irrigation did not significantly affect the mean harvest index, but itincreased seed yield, due to an increase in aboveground dry matter. In all treatments,seed yield of Hyola401 hybrid was more than that of RGS003, due to higher harvestindex. The relations of sowing date and supplemental irrigation with dry matterdistribution, can be used incrop modeling.

Five rice genotypes (Hassani, Dailamani, Shastak-mohammadi, Sange-tarom andDaei-shastak) and their 10 hybrids obtained through half a diallel set were evaluated forcombining ability and gene effects studies of early maturity and yield traits. Singleseedlings of each entries were transplanted at 20×20 cm spacing in 2×4 m2 plots using arandomized block design with three replications during 2004-2005 at research station ofSari Agricultural Sciences and Natural Resources University. General combining ability(GCA) and specific combining ability (SCA) were calculated for these agronomic traits.The results showed significant difference between general (GCA) and specificcombining ability (SCA) for the investigated characters. This indicates the role ofadditive and non-additive gene effects in inheritance of the traits. Also the resultsshowed that selection for early maturity and yield characters can’t well succeed,because of there were a high amount of non-additive gene effects in the geneticvariance. Thus, these characters were important for production of hybrid variety andapplication of heterosis. In this study, investigation of graphic Wr-Vr analysis for earlymaturity indicated overdominance effect because the regression line intercepted the Wraxis at negative point (a = -6.64). The GCA effects of each parent for these traitsshowed that the Daei-shastak is good general combiner for yield.

Ratooning means regrowing of rice plant after harvesting of first product which isspecific physiologic characteristic of rice plant. It is an effective method for increasingof efficiency of production along with less investment and also lack of necessity forincreasing of the field of rice plant. Ratooning more over, affects on the optimal usageof agricultural field. In order to achieve this goal, the use of important and effectivefertilizer elements will be useful. In order to investigate of the effects of different levelof nitrogen and potassium on ratooning of rice, an experiment was conducted in GuilanProvince (Amlash) during 2003. The experiment was carried out suing factorial in acomplete randomized block design with eight treatments and three replications.Treatments were included 0, 50, 100 and 150 kg N / ha from source urea and 0 and 100kg K / ha from source chloral of potassium (KCL). In this experiment grain yield, yieldcomponents, harvest index, biological yield and straw dry weight were investigated.According to results effect of nitrogen was significant on grain yield, percentage offilled, grain number panicle in m2 and harvest index (HI) at 1% and on 1000 grainweight and biological yield at 5%. Effect of potassium was significant on biologicalyield, percentage of filled grain and number of panicle in m2 at 5%. Interaction betweennitrogen and potassium was significant on, grain yield at 1% and on number of paniclein m2, biological yield and harvest index (HI) at 5%. In conclusion, it can be said thatthe effect of fertilizer on ratoon yield is significant and positive in comparison to lack ofusage of it.

In order to investigation the effect of different organic fertilizers amounts (municipalcompost, vermicompost and sewage sludge) on yield and yield components of differentsoybean cultivars, an experiment was conducted in 2006 at Sari Higher Education Complexof Agricultural Sciences and Natural Resources. A split plot experiment based onrandomized complete block design with three replications was used. Main plots wereincluded 8 fertilizer treatments consisted of two rates (20 and 40 ton ha-1) of municipalcompost, vermicompost and sewage sludge, chemical fertilizer treatment (the 75 kg ha-1 of potassium soulphat and ammonium phosphate) and control or without organic or chemical fertilizer. Sub plots consisted of three genotypes of soybean (032, 033 and JK). Maximum grain yield was recorded in levels of 20 and 40 ton ha-1 sewage sludge, 40 ton ha-1 municipal compost and chemical fertilizer. Different soybean cultivars had significantdifferences in terms of yield and yield components. Among different cultivars maximumgrain yield were produced in JK and 033 cultivars. The result of mean comparisons showedthat interaction effects of fertilizer and cultivar were significant for biomass, harvest index,1000 seed weight, number of pod per plant and number of seed per pod. The highest pod number per plant was belonged to JK and 033 genotypes in 40 ton per hectare sewage sludge and vermicompost treatments, respectively. Among different mentioned traits, all of them except 1000 seed weight had a positive and significant correlation with grain yield.Over all, it seems that disposal of organic waste on agricultural lands could be consideredas one of the suitable and practicable environmental option and optimization manure usingin our country.