فصلنامه علوم زراعی ایران
سال نهم شماره 3 (پیاپی 35، پائیز 1386)

To study the drought tolerance in some of grain maize hybrids, this study was carried out in Qom province in 2006 cropping season. Twenty maize hybrids were evaluated in randomized compelet block design with four replications, in two separate expriments, under normal irrigation(30% depletion of available water) and drought stress (60% depletion of available water). Results of analysis of variance for grain yield and its components showed variation among hybrids under normal and drought stress conditions. The highest yield under normal and stress conditions belonged to hybrids BC504 and BC652, repectively. While, hybrids BC678 and NS504 showed the lowest yield under normal and stress conditions, respectively. To evaluating the response of hybrids to drought stress, different indices, including, Stress Susceptility Indices (SSI), Harmonic mean (Harm), Tolerance index (TOL), Mean Producivity (MP), Stress Tolerance Index (STI) and Geometric Mean Productivity (GMP) were used. Different indices revealed hybrids BC504, BC652, BC404, KSC302, KSC320 and KSC647 as tolerance under stress condition. STI, MP, GMP and Harm indices, were identified as suitable indices to be used in applied maize breeding programs. These indices showed the highest corrolation between grain yield under normal and drought stress conditions.

In order to investigate the effect of different levels of nitrogen and boron fertilizers on canola grain protein, oil and yield, in Ahwaz region, an experiment was conducted in 2005-2006 cropping season in Ramin Agriculture and Natural Resources University. The experimental design was a randomized complete blocks with three N rates (150, 200 and 250 kg/ha) and four B rates (0, 2.5, 5 and 10 kg/ha). All treatments were replicated four times. Result showed that with increasing nitrogen rates, grain and oil yield significantly increased. Application of boron also significantly influenced grain yield. Nitrogen × boron, on grain and oil yield was not significant. However, highest grain and oil yield was obtained from 250 and 10 Kg/ha N and B, treatment. With comparison of treatments it was observed that 200 Kg N/ha with 10 Kg B/ha produced grain and oil yield higher than 250 Kg N/ha without Boron. Grain protein and oil contents with increasing of nitrogen levels were significantly increased and decreased, respectively. But boron application had no effect on grain protein and oil contents. Results also showed that relationship between grain yield and grain oil and protein contents can be showed with a logarithmic equation. These relationships was significantly affected by nitrogen levels. With increasing of nitrogen rates, reduction of grain oil and protein contents, were slower in higher levels of grain yield. Although, effect of boron were small on this traits, but grain oil and protein contents in higher levels of grain yield was less than lower yields.

To study genotype×environment interaction and stability of grain yield in bread wheat genotypes, 20 promising winter and facultative bread wheat lines were evaluated for grain yield (YLD) in 10 locations in 2001/02 and 2002/03 cropping seasons. Ten locations included Karaj, Zanjan, Ardebil, Arak, Miandoab, Jolgerokh, Mashhad, Hamedan, Eqlid and Tabriz. Experimental design in each environment was randomized complete block (RCB) with three replications. Stability parameters including environmental variance, environmental coefficient of variation, Wricke´s ecovalence, stability variance of Shukla (σ, regression coefficient, deviation from regression, coefficient of determination, intra-locational variance (MSy/l) and simultaneous selection for grain yield and stability (YS) were estimated. Results of stability analysis showed that based on the most methods, lines C-80-14, C-80-19 and C-80-20 were determined more stable than the otherse considering the majority of the statistic parameters. However, based on simultaneous selection for yield and stability method genotypes C-80-4, C-80-6 and C-80-11 were identified as the superiors. Among these genotypes, C-80-4 and C-80-6 were further evaluated in on- farm and verification trials in farmers´ fields in different regions of cold zone which based on the results they produced higher yield than the commercial cultivars of the regions.

A field experiment was conducted to evaluate the effect of different levels of plant density and nitrogen fertilizer (N) on grain yield and its components and some quality traits in two sesame (Sesamum indicum L.) cultivars-using split-split plot arrangement in randomized complete block design with three replications at Agricultural Research Station of Kushkak, College of Agriculture, Shiraz University in 2002 cropping season. The treatments included: plant density (16.6, 20.8, 33.0 and 41.6 plants m-2) assigned to main plots, nitrogen fertilizer (N) (0, 60, and 120 kg ha-1) and cultivars (CV) (Local Zarghan and Darab-14) were randomized in sub-plot and sub-sub plots, respectively. Both plant density and N fertilizer had significant effect on days to maturity, capsule number per plant, 1000-grain weight, grain yield, harvest index, oil and protein contents. Grain yield of cultivars increased with increased N rate, but CVs had different response to N levels. There was a significant interaction between N × plant densities × CV on grain yield, and the highest grain yield (2161 kg ha-1) was produced by Darab-14. in 41.6 plants m-2 and 60 kg N ha-1, which was not significantly different from local Zarghan, at this plant density. Grain yield had negative and significant correlation (r= -0.31*) with harvest index and positive correlation (r= 0.23) with 1000-grain weight and oil content. Grain oil content had negative and significant correlation (r= -0.86**) with grain protein content. In summary, two sesame cultivars had no significant yield differences, but it local Zarghan, was more responsive to N application. Of course Darab-14 is harvested later relative to local Zarghan and therefore, it is recommended early maturity local Zarghan be sown where there are early autumn rain and cold with less N fertilizer application.

In order to study the effect of plant density and planting method on forage yield and quality of four grass pea (Lathyrus sativus L.) ecotypes, a field experiment was carried out during 2005 summer season in Hidaj town (Zanjan province, Iran). Treatments were arranged in a factorial experiment using Randomized Complete Blocks Design with four replications. Grass pea seeds of Zanjan, Ardabil, Shahre-e-Kord and Mashhad ecotypes (E1-E4) were sown in two planting methods (flat plots and furrowed plots) (P1 and P2) at two plant densities (110,000 and 220,000 p.ha-1) (D1 and D2) on July 28, 2005. The former crop was wheat. Seven destructive samples were taken during grass pea growing season to study the trend of CGR and RGR. Different quantitative traits (plant height, forage fresh and dry yield) and quality traits [DM(%), crude protein(%), Ca(%), P(%) and NDF(%)] of forage were measured. Result showed that grass pea grown in flat plots had higher CGR and RGR. Also fresh and dry forage yield in flat plots with 220000 p.ha-1 were significantly more than furrowed plots with 110/000 p.ha-1. Mashhad ecotype by producing 29.4 t.ha-1 fresh forage yield and 5.98 t.ha-1 dry forage yield was the best forage producer among all ecotypes. However, there was no significant difference between Mashhad, Zanjan and Shahre-e-Kord ecotypes. The Ardabil ecotype produced the lowest forage yield as 21.7 t.ha-1 and 2.66 t.ha-1 for fresh and dry weight, respectively. Plant height in dense plots (220000 p.ha-1) was significantly higher than 110,000 p.ha-1. Crude protein percent was significantly affected by all factors. Main effects of planting method and plant density were significant for Ca% and NDF%. Phosphorus percent has not affected by any of experimental factors. The Ardabil, Zanjan and Shahre-e-Kord ecotypes were superior for CP%, NDF% and Ca%, respectively. It can be concluded that P1D2E4 system (Mashhad ecotype sown in flat plots with 220000 p.ha-1) was superior.

The effect of row spacing on grain yield, yield components and oil content of four rapeseed (Brassica napus L.) cultivars was investigated in a paddy fields as second crop after rice at Rice Research Institute of Iran (Rasht), in 2003-2004 and 2004-2005 cropping seasons. The experiment was conducted as a split plot arrangement in a randomized complete block design with four replications. Four rapeseed cultivars: Hyola308, RGS003, PF7045/91 and Hyola401 were assigned to main plots and three row spacings: 20, 25 and 30 cm at constant plant densities` (40 plant/m2) were randomized in sub-plots. Results showed that rapeseed cultivars were significantly different in grain yield, oil content, oil yield, biological yield, days to maturity, number of siliques per plant, number of grains per silique, silique length, 1000- grain weight, number of first, second and third order auxiliary branches, and plant height. Results also indicated that, PF7045/91 ranked the first in grain yield, oil content, oil yield, biological yield, days to maturity, number of siliques per plant and number of first and second order branches and plant height. Row spacing had significant effect on biological yield, harvest index and days to maturity, but its effect on grain yield, oil content and oil yield was not significant. However, row spacing of 20 cm ranked the first in grain yield, oil content, and oil yield. Correlation coefficients between traits indicated that grain yield was significantly correlated with number of siliques per plant, second order branches and plant height. Number of siliques per plant and plant height were significantly correlated with oil content. Results showed that PF7045/91 ranked the first in light interception (LI%) and radiation use efficiency (RUE) (75.5% and 2.33 g.MJ-1, respectively) and Hyola308 ranked the least (61.5% and 1.54 g.MJ-1, respectively). Row spacing of 20 cm also ranked the first in light interception (68.5%).

This experiment was conducted to study straw and grain yield and morphological traits in 10 common millet by using a RCB design with three replications in Karaj, Dezful and Gorgan in three consecutive growing seasons (2000-2003). Data were recorded on traits such as tiller no.plant-1, leaf no.plant-1, stem diametere, days to 50% flowering, panicle length, seed number per panicle, 1000- grain weight. The grain and straw yields of each variety was also determined by harvesting a 5 m2 area of two center rows in each plot, and the weights were then adjusted to 14% of moisture. Results indicated that there were significant differences for all traits among varieties at 0.01 probability level, except for, days to 50% flowering and straw yield. Mean comparisons showed that var. 2 with 9.2 leaves, var. 9 with the stem diameter of 8.54 mm, var. 1 with panicle length of 35.7 cm, var. 9 with 1111 grain per panicle, var. 9 with 1000- grain weight of 5.16 g, and var. 3 with the grain yield of 1.859 t/ha had the highest values among the other varieties. Meanwhile, the results showed that there were significant and positive correlation between straw yield and number of grain per panicle (0.695*) but there were significant and positive correlation between grain yields and tiller number per plant (0.657*), leaf number per plant(0.677*), days to 50% flowering(0.782*) and straw yield (0.782*).