v. rameeh

Aram is a new oilseed rape cultivar, extracted from the R308 (earlness line) and RGS003 (high-yield cultivar) cross population through pedigree method in three years. To reach high-yielding and compatible lines and cultivars, preliminary and advanced investigations were carried out in Gorgan and Sari (2014-2015) and Zabol, Gorgan, Sari and Borazjan (2016-2017). The line SRL-93-12 (Aram cultivar) with a yield of 2955 kgha-1 and 2774 kgha-1 was the first in the above-mentioned tests, respectively, and the SRL-93-12 line was also recognized as the most stable genotype based on the lowest Lins and Binns superiority index and highest seed yield. Extension research project results on farmers' farms in Behbahan, Moghan, and Gorgan regions showed that the new line with 594 kgha-1 higher yield than the check cultivar was in the first rank. According to the results as well as desirable agronomic traits such as good tolerance to dormancy and uniformity in maturity, this line was released with the name Aram.

The south warm climate of Iran is one of the regions with the ability to grow spring oilseed rape cultivars. Cultivation of oilseed rape in this climate faces the problem of environmental stress such as terminal drought and heat stress. Therefore, in addition to yield, earliness is one of the important priorities to introducing spring oilseed rape cultivars in these areas. Asa (promising line SRL-93-4) is an early-maturing and relatively high-yielding cultivar that resulted from hybridization between R308 early-maturing spring line and Modena as a high-yielding winter cultivar. The segregated generations were conducted by pedigree method. Preliminary and adaptation trails showed that SRL-93-4 line was superior compared to check cultivars in the regions under study. In the adaptation trail, the SRL-93-4 line (with 2581 kgha-1 seed yield) showed a significant superiority over the control cultivar RGS003 (with 2155 kgha-1 seed yield). Also, it was found that the SRL-93-4 line was matured 11 days earlier than the check variety RGS003 on the average. The results of stability methods revealed that SRL-93-4 line was the high stable genotype. A field trial for Blackleg disease showed that the SRL-93-4 line had a relative tolerance to the Blackleg. Analysis of the fatty acids profile showed that SRL-93-4 seed oil had a level of erucic acid close to zero, and in terms of the composition of fatty acids, it was within the standard range, but with more oleic acid and less linolenic acid compared to the RGS003 variety. Also, the amount of glucosinolate of the meal was less than standard level. The results of the on-farm trails in Zahak and Zabol regions of the Sistan and Baluchestan province showed that SRL-93-4 line (with 2200 kgha-1 seed yield) had a non-significant difference seed yield with Dalgan check cultivar (with 2361 kgha-1 seed yield); But it was eight days earlier than the check variety. Therefore, due to the desirable characteristics such as early maturity, relative tolerance to Blackleg disease and good performance, the new promising line SRL-93-4 which released as Asa variety is recommended for cultivation in the south warm regions of the country.

Saffar (Zabol 10b line) variety was obtained by pedigree method from Goliath×19H cross. Based on preliminary evaluation, this variety showed significant earlier maturity (13 day), in 2010-2011, compared to the other lines of canola. Based on adaptability expieriments in Zabol, Safiabad, Behbahan, Boushehr, Gorgan, Gonbad, Sari and Moghan regions in 2011-2012, its grain yield had not significant difference from control variety RGS, but had a high early maturity. The new variety had a lower rank variance which indicates the Less performance fluctuations and stability in different years and regions compared to control variety RGS. Saffar cultivar with 165 days growth period was 12 days earlier in maturity than control variety RGS in warm south and north regions. The oil content of new variety was 43.15%, which has not significant difference with control variety RGS but in terms of having higher amounts of oleic acid and lower amounts of linolenic acid, it has a better quality. The field response of new variety to stem sclerotinia disease showed good relative tolerance in the north climate, which has significant difference with control variety RGS. Based on outstanding features such as yield stability, early maturity, possibility of escaping from drought and heat in the last season, saving at least one irrigation stage and uniformity in maturity, this line was released with the name of Saffar in 2018 and recommended for late cultivation in warm areas with short growing seasons in warm south and north climate zones of the country such as the south of Kerman, Sistan and Baluchestan, Hormozgan, Khuzestan and Gorgan.

The phenomenon of genotype × environment interaction has important implications for selection of superior genotypes which remains as one of the main goals of crop breeding programs. To investigate the seed yield stability of promising spring rapeseed lines in four field stations in southern warm and dry and northern warm and humid agro-climatic zones of Iran. Sixteen open pollinated spring promising rapeseed lines were sown in randomized complete block design with three replications in two cropping cycles (2015-16 and 2016-17). Combined analysis of variance revealed that the effect of environment on seed yield was significant (P < 0.01). Genotype × environment interaction effect was also significant (P < 0.01) on seed yield. GGE biplot analysis identified four mega-environments; Gorgan (Line G8), Sari (Line G4), Sari-Zabol (Line G13) and Zabol (Line G7). Lines G4 (Asa), G8 (Roshana) and G13 (Aram) with average seed yield of 2714, 3349 and 3817 kg ha-1, respectively, had higher seed yield and yield stability. Line G4 had the highest seed yield stability. Line G11 (RGS003) with 2155 kg ha-1 was identified as low yielding with low seed yield stability. Generally, grouping of spring rapeseed lines based on genotype × environment interaction using GGE biplot analysis is a useful approach for selection and releasing of spring rapeseed cultivars with high seed yield potential and yield stability for target environments.

In order to study the general combining ability(GCA), specific combining ability (SCA) and heredity ability in rapeseed, eight genotypes were crossed using line×tester method. Fifteen hybrids together with eight parents were compared in RCBD with three replication during 2002-2003 at Agricultural Research Station of Bayekola, Mazandaran. Mean of squares of GCA and SCA were significant for many of traits indicating significant differences for GCA effects of parents and SCA effects of hybrids. Estimation of degree of dominance more than one, and low heritability for plant height, total number of pods per plant and seed yield, indicated over-dominance gene effect and prime importance of non-additive gene effect for controlling above mentioned traits. Thus, producing hybrid seed for utlization of non-additive gene effects of these traits will be fruitful. For number of days to maturity,1000-seed weight and oil percentage, additive gene effects were more important. Thus, breeding based on selection for these traits will be effective. Among parents, Quantum and Legae and among testers, Foseto had high significant GCA effect for seed yield and some other traits. Therefor, these genotypes can be used for seed yield improvement. Among crosses, Foseto × Legae had the highest seed yield and high amount of SCA effect for number of seed per pod, number of pods plant and 1000 seed weight. In general the crosses with high SCA effect for seed yield, had at least one parent with high GCA effect, thus selection based on GCA effect of seed yield can be effective for improving SCA effect of seed yield

For better better use of paddy lands in Mazandaran province, this study was carried out to determine the best planting date, plant density and nitrogen fertilizer levels for high yield in cauliflower cv. Snow crown. The experiment was conducted in a spilt-plot factorial design with three replications at Dashtenaz Agricultural Research Station in Sari for two years (2003-2004). The main plots were three planting dates, 5 Sep., 20 Sep. and 5 Oct., subplots three plant row distances, 50, 60 and 70 cm and three levels of nitrogen fertilizer 0, 92 and 138 kgha-1. Analysis of variance revealed significant differences among main factor, sub factors and also their interactions at 1%probability level.The highest yield (40 tha-1) was produced in treatment with planting date of 5 Sep., plant density of 60 cm (55000 plants per hectar) and application of 90 kgha-1 nitrogen. Increase in plant number per hectare by reducing plant row distances from 70 to 60 cm increased the total yield. Significant positive correlation was observed (r = 0.842) between curd diameter and fresh leaves weight. Significant positive correlations were also observed between yield and curd diameter (r = 0.580) and leaf dry weight (r = 0.545). The results of stepwise regression analysis revealed that curd diameter and leaf dry weight were the most important factors affected the yield. Accomulated nitrate did not show any significant correlation with yield and its amoumt in different treatments were acceptable.

Diallel crosses of six breeding inbred lines of corn (Zea mays L.) were used to estimate combining abilities, heterosis and some other genetic parameters for yield and some of its components. Parents, 15 F1 crosses and 4 filler genotypes, were evaluated in a 5×5 simple lattice design. For all the traits studied, except seed length, the efficiency of lattice design was less than one. Therefore, data were analysed as a randomized complete block and after eliminating the filler genotypes, Grriffing’s method 2 with mixed B model was used in the genetic analyses. General and specific combining ability (GCA and SCA) mean squares were statistically significant for all traits studied. The ratios of GCA to SCA mean squares were greater than one for all traits, except for the number of seed rows per ear, indicating the importance of non-additive gene effects in their genetic control. Low heritability estimates and degrees of dominance lower than one were further evidence of the presence of non additive gene effects for all the traits studied, except for the number of seed rows per ear. Therefore, production of single cross hybrids in order to take advantage of non-additive gene effects is of prime importance for grain yield, number of seeds per ear row, l00-seed weight, seed length, ear length, and comb percentage. For genetic improvement of number of seed rows per ear, selection methods for parental lines will be more efficient. In the hybrids studied, number of seed per ear row and l00-seed weight played a more important role in the observed variations in yield. In general, hybrids 4×5 and 5×6 with high SCA for number of seed per ear row, l00-seed weight and grain yield were considered favorable for the conditions of this study.