JOURNAL OF CROP PRODUCTION RESEARCH (ENVIRONMENTAL STRESSES IN PLANT SCIENCES)
Year:2009 | Volume:1 | Issue:1|Papers Count:8

In order to study on maize hybrid cultivars in related to humidity stress and investigation and identify correlations between different traits in maize genotypes under research study conducted in North- ,west of Khom province in Shekoohia small city. Number of 20 maize hybrid wereftudied in the base of randomized complete blocks design in 4 replications and at two separated experiment under normal humidity condition (irrigation after 30% humidity depletion of water available) and drought stress (irrigation after 60% humidity depletion of available water). Variance analysis of trai-ts in normal and drought stress conditions showed that between investigated traits of maize hybrid were noticeably variant. The highest variant rate among two irrigation conditions related to ASI trait (-51.62). In both of irrigation conditions, heritability of 1000 seed weight, hectoliter and grain yield were the highest in compare to others traits. Study of traits correlation in normal irrigation showed that the yield with traits of hectoliter, 1000 seed weight, row seed number and seed number per row had positive significant correlation. In drought stress condition observed high negative correlation significant and among yield and ASI (-0.83), days to silky flower initiation and days to tassel flower initiation. In the other hand, the yield related to seed number per row (0.82), row seed number per ear (0.75), seed depth and 1000 seed weight showed high positive correlation. Study of the direct and indirect effects in effective traits in normal condition showed that the highest direct effect on grain yield relate to seed row number (0.868). Iin drought stress condition direct effect seed number per row (1.778) and seed number per ear was positive and upper than others and tassel peduncle length as directs effect on grain yield related to traits residual was highest adversely. The ASI traits by reducing seed number per row had High effect in reduction of yield in stress condition indirectly. The results showed that the best ways for grain yield increasing is direct selection for increasing yield components and should be considered specially for selection of tolerant plants to drought relate to reduction of ASI time, days to tassel flower initiation and days to silky flower initiation traits.

In order to study the Inheritance of resistance to yellow rust disease stress in bread wheat a generation mean analysis was used. The study material included six generations (susceptible and resistant parents, F1, F2, BC1 and BC2) in crosses between Elitlep (resistant) and Bolani (susceptible). Seedlings were grown in greenhouse until the first leaves fully expanded and then inoculated with 6E130A+ pathotype (race) of yellow rust and infection type was recorded. Results of generation mean analysis and segregation ratios in F2 population indicated that 1 to 2 genes were responsible for infection type. Dominant and Additive´Dominant gene effects were significant in genetic control of infection type. Broad-sense and narrow-sense heritabilities were estimated to be 89% and 68% respectively. The direction of dominance for infection type was toward higher resistance. Transgressive segregation was observed for both lower and higher infection types.

Drought stress is one of the most important inhibitor factors of plant grow in all over the world. Polymers composed organic synthetic and generate from artificial process. These materials could be able to absorb and keep water several times of their volume rapidly. The following research carried out with the purpose of investigation the effects of different levels of water deficiency stress and super absorbent on yield and antioxidant activities of mustard (Sinapis Alba L.) in research station of the Islamic Azad University, Karaj branch. This experiment was as factorial in the basis of randomized complete blocks design with 3 replications that water deficit stress in 5 levels (Irrigation after 80 mm evaporation from class A evaporation pan, Stop irrigation after stem elongation stage, Stop irrigation after flowering stage, Stop irrigation after pod formation and Stop irrigation at early stage of grain filling) and super absorbent polymers application in 3 levels (concentration of 0, 5 and 7 percent). The results showed that simple effect of drought stress and polymers effect on all characters had significant difference but interaction effect on all characters showed no difference.The results indicated that normal irrigation in 80 mm evaporated water from class A evaporation pan and %7 selenium application gained to maximum amounts of seed yield , biological yield and harvest index with 5803 Kg/ha , 25780 Kg/ha and %25/45. The Highest amounts of antioxidant enzyme activity conducted in irrigation after 80 mm evaporated water from class A evaporation and non-utilization of superabsorbent hydro gels.

In Iran, the most extension regions growing cereals, suffer from severe drought. One of the reliable crops for these situations is barley. A low success in developing barley tolerant genotypes is, at least partially, due to a low selection efficiency using multiple agronomic parameters and lack of effective evaluation methods for drought tolerance selecting genotypes in screening processes. Four hulls-less barley genotypes (UH3, U46M, EHM81- 12 and CM67) were grown in Research Station of Eghlid Azad University by two different experiments under drought stress study in two years (2005 and 2006). Four water supply treatments (irrigating after the soil water potential reached -.0.5 bar (control), 1.5 bar, -3 and -5 bar) were used. The experimental design was a split plot in which drought treatments were arranged as main plots and genotypes as subplots, based on a randomized complete block design with three replications. The measured parameters were growth relations, water potentials and water relations. The germination test in dry conditions was carried out and germinating percent and shoot and root length and weight were measured. The present study demonstrated that the number of leaves per plot was reduced significantly by stress. LAR was less sensitive to stress. Among the genotypes UH3 had the lowest and CM67 the highest growth amount. The Growth differences were related to low plant water content. Drought stress caused decreasing in water ratios and potentials in leaf, RWC, WUE, RGR, CGR, NAR and LAI ratios, seed germination and seedling growth. LAR value was first decreased by stress treatments but showed an increase at high stress levels.

In order to investigate the effect of seed hardening on yield, yield components and harvest index of common bean, variety Akhtar in water stress conditions, a two year experiment was conducted at the experimental farm of the Islamic Azad University of Shahre-rey, in Tehran, Iran, during 2007 and 2008. The experiment was set up in a split plot on the basis of complete block design with four replications that placed two water stress levels (no stress and stop irrigation at the flowering stage) in the main plots and five levels of seed hardening (12 hours soaking and 12 hours drying of seeds at three times, 12 hours soaking and 12 hours drying of seeds at four times, 24 hours soaking and 24 hours drying of seeds at three times, 24 hours soaking and 24 hours drying of seeds at four times and no hardening of seeds) in sub plots. Results showed that in water stress conditions, seed hardening especially 24 hours soaking and 24 hours drying of seeds at four times increased yield, No. pod, 100-seed weights and harvest index. In no water stress conditions, the effect of seed hardening on measured traits was not significant.

To evaluate the effect of drought stress on yield, yield component and spike related traits in wheat cultivars, an experiment carried out in a strip-plot experiment with a randomized complete blocks design with three replications at Seed and Plant Improvement Institute in Karaj region in 2005. In this experiment four irrigation levels control (a1), mild stress(a2), moderate stress(a3), high stress(a4) and eleven cultivars were levels of horizontal and vertical factors respectively. Stress conditions was applied with line source sprinkler to irrigate cultivars, so amount of water used for each treatments were:(a1=5700 cubic meters, a2=4500cubic meters, a3=3000cubic meters, a4=2100 cubic meters). After harvest, traits including: Grain yield, 1000 kernel weight ,number of spike per plant, spike length, spikelet number per spike, main spike weight, number of kernel per spike, sterile spikelet number and grain yield in main spike were recorded. Analysis of variance showed that there were significant differences among all cultivars and irrigation levels and droughut, stress reduced all traits. Compa, risons of means showed that Sardari and Azadr2 cultivais were significantly (a=5%) better in Grain yield, 1000 kernel weight, number of spike per plant and spike weight than others. Also optimum irrigation level was better than other treatments. Finally between yield and yield components, positive and significant correlation observed?

In order to Study the base nitrogen Stress on roset stage plant weight and final plant weight of Rapeseed (Brassica napus L.) Cultivars, an experiment carried out in factorial design on the basis of randomized complete blocks with 4 replications over 2003 -2005 that base nitrogen fertilizer in 3 levels (0 ,50 and 100 Kg/ha pure nitrogen) and Rapeseed cultivars in 6 levels Talaye , SLM046, Okapi, (Zarfam) Regent*Cobra, Licord and Orient considered.The effect of base nitrogen on roset did not have significant difference but the effect of this factor on final plant weight had significant difference at 1% level.The results of mean compaison showed that after increase in base nitrogen to 100Kh/ha, average amount of roset stage plant weight and final plant weight increased to 342 and 1551 g/m2 alternatively.The effect of cultivar on roset stage plant weight and final plant weight had significant difference at %1 level. In this condition maximum amount of roset stage plant weight with 396 g/m2 and final plant weight with 1521 g/m2 belonged to Orient cultivar alternatively.The interaction Effect of Base nitrogen and cultivar on roset stage plant weight and final plant weight had significant difference at %1 level. In this condition application of 100Kg/ha base nitrogen in Zarfam with 586 g/m2 and the same application in Licord with 1761 g/m2 gained to maximum roset stage plant weight and final plant weight .

Variation of chlorophyll fluorescence can use as an index in evaluation of plant tolerance to physiological and environmental stress. In this order an experiment was conducted at Karaj in 1999. Research was carried out in factorial based on RCBD with 3 replications. Drought and non-drought stress treatments with 9 sugar beet genotypes were randomized. Results showed that Fo was higher in stress than non-stress condition (P<0.05). Fm was higher in stress than non-stress condition (P<0.05). Fv was lower in stress condition and genotypes had not significant difference (P<0.05). Photosynthetic efficiency (Fv/Fm) was significantly reduced in stress condition (P<0.05). Genotypes had significant difference in Fv/Fm (P<0.01). Fv/Fm reduced in stress and genotypes means showed lower Fv/Fm in stress. As FyZ,Fm has a high correlation with photosynthetic quantum yield therefore in genotypes / with lower Fv/Fm, there was more sensitive photosynthetic system under drought stress. There was positive correlation between Fv/Fm and root yield but it was not significant at 5% level of probability. Results showed that there was positive correlation between Fv/Fm and stomata conductivity but it did not significant for leaf adaxial surface with 0.158 and leaf abaxial surface with 0.257 at the 5% level of p-f-obability.It found that as stomata conductivity reduced in stress condition.