فصلنامه علوم زراعی ایران
سال پانزدهم شماره 4 (پیاپی 60، زمستان 1392)

To study the effect of biological phosphorous fertilizer and different quantities of chemical phosphorous fertilizer on kernel yield of maize cv. SC704 a field experiment was conducted in agricultural research farm of University of Tehran in Karaj، Iran، in 2009. Treatments were arranged as split plot in randomized complete block design with four replications. Experimental treatments included: three levels of biological phosphorous fertilizer; Barvar-2 (control، seed inoculation، seed inoculation + foliar application) and four levels of chemical phosphorous fertilizer (control، 20، 40، 60 kg. ha-1 of super phosphate triple). Results showed that the effect of biofertilizer was significant on kernel yield، number of kernel. ear-1، 1000 kernel weight، weight of kernel. ear-1، biological yield، harvest index and ear diameter. The highest kernel yield (13131 kg. ha-1) belonged to seed inoculation + foliar application of biological phosphorous fertilizer. Results also showed that chemical phosphorous fertilizer had significant effect on all traits except the number of number of kernel. ear-1. The highest kernel yield (12855. 8 kg. ha-1) was obtained in 60 kg. ha-1of chemical phosphorous fertilizer. Furthermore، the interaction effect of treatments showed that the application of biological and chemical phosphorous fertilizers was significant on all traits except the number of kernel. ear-1، ear diameter and harvest index. The highest grain yield was obtained from seed inoculation + foliar application with biological phosphorous and 60 kg. ha-1 chemical phosphorous fertilizers. Results of this experiment showed that the biological phosphorous fertilizer contains microorganisms which could solve phosphorous in the soil، promoted growth and uptake of phosphorous by maize plant and increased grain yield.

Fourteen promising maize hybrids together with commercial check hybrid، KSC 704، were evaluated using randomized complete block design with four replications in 12 locations (Karaj، Shiraz، Ghaemshahr، Mogan، Khoram Abad، Miandoab، Mashhad، Gorgan، Dezful، Esfahan، Jiroft and Iilam) for two cropping seasons (2011 and 2012). Analysis of variance and mean comparison of two years in each location showed that hybrid KSC 703 produced the highest grain yield in Karaj (13758 kg. ha-1)، Shiraz (14190 kg. ha-1)، Ghaemshahr (11084 kg. ha-1)، Gorgan (9227 kg. ha-1)، Isfehan (10784 kg. ha-1) and Jiroft (10556 kg. ha-1). It obtain the second rank for grain yield in Miandoab (19470 kg. ha-1) and Khoram Abad (6303 kg. ha-1) and third in Moghan (10010 kg. ha-1) and Mashhad (14730 kg. ha-1). The highest grain yield averaged over locations in 2011 and 2012 belonged to hybrids KSC 703with 12260 and 11321 kg. ha-1، respectively. Mean comparison، averaged over years and locations، revealed that hybrids KSC 703، KSC 702 and KSC 705 produced higher grain yield with 11290، 10965 and 10133 kg. ha-1، respectively. Superiority measure (Pi) revealed KSC 703 (Pi 0. 06)، KSC 702 (Pi=0. 78) and KSC 705 (Pi=1. 70) as superior hybrids. Based on grain yield and superiority measure، which combines high yielding and stability، hybrid KSC 703 was identified as the most promising hybrid for commercialization، should it performs successful in on-farm verification trails.

Simultaneous effect of salinity and drought stresses and their critical limits imposed on cv. Hashemi (most common rice cultivar in Guilan province) was investigated. Also the best model to estimate the reduction of plant''s water absorption due to simultaneous interaction of salinity and water stresses was identified. Experimental treatments consisted of three levels of irrigation; continuous flood irrigation 3 cm water height) and two intermittent irrigation (4 and 8 days intervals) and five levels of salinity by using irrigation water with electric conductivity of 1, 2, 3, 4 and 5 dS.m-1applied in factorial based randomized block design with four replications. Results indicated that for rice plant yield loss threshold due to drought stress occurred at soil moisture about 80% of saturation. Salinity threshold for this cultivar was at soil extraction of 2.83 dS.m-1 which implies it’s sensitivity to salinity. Among the evaluated models, the best model for predicting the reduction of plant''s water absorption due to simultaneous effect of salinity and water stresses is Homaee and Feddes for rice. In this model, by subtraction of yield reduction threshold osmotic pressure from the soil water pressure in permanent wilting point, simultaneous effect of salinity and water stresses assumed to be less than total or product of these stresses. It is concluded that under conditions when drought and salinity stresses are not balance, predictions by this model are closer to observation and the prediction of relative low grain yield is possible.

Ninety-four rice genotypes were evaluated for genetic diversity using 52 rice SSR markers linked with some important agronomic and grain quality characteristics which well distributed on 12 chromosomes of rice. The total number of polymorphic alleles was 361 alleles with the average of 4. 750 alleles per SSR locus. Results revealed that some markers such as RM276 and RM5642 on chromosome 6 and RM14 and RM1 on chromosome 1 have more than 9 observed alleles. The highest and lowest PIC values were observed for primers RM5642 (0. 854) and RM207 (0. 515)، respectively. Cluster analysis using complete linkage method based on Jaccard similarity coefficient for molecular data showed that all genotypes were classified in nine clusters. Nine cultivars/lines from different cluster including Daylamani، Tarommohali، Line 23، RI1843046 (Saleh×Hashemi)، RI1843223 (Saleh×Mohamadi)، IR50، Back cross line [(Saleh×Abjiboji) ×Abjiboji]، R 184421 (Sepidrod×Hassansaraiee) and RI184472 (Sepidrod×Gharib) were selected as parents to be used in rice breeding programs. The similarity coefficient was very low among the selected parental cultivars/lines. Therefore، high diversity in breeding populations is expected by using these selected cultivars/lines as parents of crosses for improvement of important agronomic and physico-chemical characteristics. Marker assisted selection as a powerful technique can be used for development of the new rice cultivars because these parental cultivars/lines were recognized by some SSR markers linked with QTLs for agronomic and grain quality characteristics.

To determine the general (GA) and specific (SCA) combining abilities 36 hybrids developed in 9 × 9 diallel crossing design were grown and evaluated in three locations (Karaj، Isfahan and Mashhad) of Iran in 2004 and 2005. Grain yield، number of kernel rows per ear and number of kernels per row were measured and recorded. All crosses were made in 2003، based on Griffing''s method 4، mixed model B. diallel hybrids were evaluated in randomized complete block design with three replications in each environment. Genotypic differences، among the hybrids، were significant for all of the traits، therefore، the genetic parameters related to the diallel method were estimated. The GCA and SCA were significant for all of the traits. The degree of dominance ranged from 0. 24 for the number of kernel rows per ear to 4. 07 for the grain yield. The values for broad-sense heritability were high (0. 98 to 0. 99) indicating that environmental variance was relatively low compared to genetic variance. As expected، the narrow- sense heritability for grain yield was very low (0. 06). This was due to relatively higher non-additive variance compared to additive variance. Among the nine parental lines only two lines KE 75039 (P2) and OH 43/1-42 (P5) had high GCA for grain yield. Only one combination (P4×P9) showed high and significant SCA for grain yield، and four hybrids demonstrated relatively high SCA for grain yield. P4 produced suitable hybrid combinations with P5، P6، P7 and P8. The five best single-cross combinations to produce early maturity maize hybrids were (P2×P9)، (P4×P7)، (P4×P8)، P4×P6) and (P4×P5). Parental lines P2، P5 and P4 can be used to develop synthetic varieties in early maturity maize breeding programs.

To map genomic locations controlling physiological and biochemical characteristics of barley under normal and drought stress conditions and to determine their relationships with grain yield an experiment was conducted at Research Farm، College of Agriculture، University of Zabol in 2011. The experiment was carried out using two randomized complete block designs with three replications under non-stress and drought stress conditions. Plant materials were 72 doubled haploid lines andtheir parents (Steptoe and Morex). Physiological and biochemical traits such as grain yield، chlorophyll content، F0، Fm، Fv/Fm، RWC، WSC and proline content were measured. QTL analysis was separately conducted by composite interval mapping (CIM) method for each trait، experiment، and for mean of two experiments. Barley molecular marker linkage map comprised of 327 RFLP markers with 1226. 3 cM length and 3. 75 cM mean distance. There were significant diffrences among genotypes for all traits and transgressive segregations were also observed in both directions (positive and negative). Eighty five QTLs controlling different traits were identified from which 72 were stable. Phenotypic variances explained by these QTLs varied from 8. 28% for proline content to 25. 66% for Fm. The highest LOD scores were obtained for Fm on chromosome 2H. Stable QTLs can be used by Marker Assisted Selection (MAS).