Journal of Plant Physiology and Breeding
Volume:4 Issue: 1, Winter-Spring 2014

Low temperature (LT) is an important environmental factor that limits the survival, productivity and geographical distribution of plants. Oil seeds are the second global food resources among which Brassica napus L. is the third annual oil seed in the world. In cold stress, some biochemical and physiological reactions occur in response to reactive oxygen species (ROS). Hence, the quantitative changes of proline, malondialdehyde (MDA) and chlorophyll (a, b, total) content were assessed in two spring canola (cv. Zarfam, cold tolerant and cv. Option 500, cold sensitive) seedlings exposed to early spring cold stress. They were first grown in a controlled growth room at 22/16 °C (day/night) and then at the 4th fully expanded leafy stage seedlings weretransferred to a cold environment (10/3 °C) for 7 d, or they were maintained continuously at 22/16 °C (Control). Leaf samples were harvested at days 0 (transferred day), 2, 4 and 7 of cold exposure period. Analysis of variance showed significant differences between the temperature treatments and also cultivars for all physiological traits. The cold tolerant cultivar showed remarkable less LT-induced decrease in chlorophylls (a, b, total) and increase in MDA and accumulation of proline compared to the cold sensitive cultivar. This assay verified the superior response of cold tolerant Zarfam canola to cold temperature.

Bread wheat germplasm tolerant to salinity with high end-use quality is required to maintain grain production in saline lands. Four spring bread wheat cultivars with different tolerance to salinity and their three F3 progenies were evaluated at four levels of salt concentrations; 0, 150, 200 and 250 Mm NaCl. Na+, K+ and Cl- concentrations in the wheat penultimate leaf and some of the biomass and yield related traits were measured. The allelic variations of Glu-1 loci in the crosses were examined. Salinity had a significant positive effect on Na+ and Cl- concentrations and the Na+/K+ ratio. As salinity level increased, yield and 1000 grain weight and K+ concentration were declined. Most of the F3 progenies did not show much improvement in terms of biomass or yield related traits. However, F3 progenies of the Cajema×Lerma Rojo cross showed an improved quality score.

The influences of different ultraviolet (UV-A, UV-B and UV-C) radiation treatments on phenolic compounds (total phenol, anthocyanin and flavonoid), lipid peroxidation content and behavior of the some enzymes such as polyphenoloxidase (PPO), phenylalanin ammonia–lyase (PAL), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT) and glutathione reductase (GR) were studied in okra (Hibiscus esculents L.) seedlings. results showed that UV-B and UV-C treatments increased UV absorbing compounds and lipid peroxidation contents as compared with the control and UV-A treatment plants. UV-A treatment did not significantly affect the activity of antioxidant enzymes (APX, GPX, CAT, GR), but in plants treated with UV-B and UV-C, APX, GPX, CAT and GR activity were significantly increased when compared with the control plants. Also activity level of PPO and PAL in the shoots of okra plants increased significantly in response to UV-B and UV-C treatments. These results suggest that the increased phenolic compounds and antioxidant system activity in the UV-B and UV-C treatments may be considered as biomarkers of intensity of UV radiation stress. However, more research is necessary to elucidate the precise role that the antioxidant system plays under ultraviolet radiation stress.

The objective of this research was to evaluate forage yield and quality of native alfalfa ecotypes. Correlations among the investigated traits were also determined, since data on relationships are of great importance in selection, especially for traits with low genetic variability. Experimental material consisted of 13 alfalfa germplasms. Investigation was carried out during a three-year period. The field trial was arranged as the randomized complete block design with four replications. There was a statistically significant difference among ecotypes for plant height ranging from 74.50 cm (Moapa) to 96.00 (Alhord), number of internodes from 12.75 (Khosrovanagh) to 16.00 (Moapa), leaf size from 0.45 (Ranger) to 1.0125 (Leghlan), leaf fresh weight to stem fresh weight ratio (LFW/SFW) from 0.44 (Leghlan) to 0.54 (Moapa), leaf dry weight to stem dry weight ratio (LFW/SFW) from 0.3725 (Leghlan) to 0.4750 (Moapa), in vitro dry matter digestibility (IVDMD) from 45.42% (Gara-Yonjeh) to 50.67% (Baftan), acid detergent fiber (ADF) from 38.83% (Khaje) to 44.70% (Gara-Yonjeh), crude fiber (CF) from 25.96% (Sivan) to 32.48% (Ranger) and neutral detergent fiber (NDF) from 47.03% (Khaje) to 57.43% (Moapa). There were positive correlations between plant fresh yield, dry yield, number of stems and plant height. LFW/SFW and LDW/SDW didnt show any significant correlation with quality components (IVDMD, CP, ADF, CF and NDF). There was a negative correlation between CP and CF. Sivan, Dizaj-Safarali, Gara-Baba, Khosrovanagh, Khaje, Alhord and Leghlan ecotypes had the best quality. They can be recommended and considered to make synthetic varieties.

The objective of this research was to study the genetic control of germination variables under normal and water deficit conditions in sunflower. A population of 100 recombinant inbred lines obtained from a cross between PAC2 and RHA266 was used in the present study. The experiment was performed as a randomized complete block design with three replications. Germination variables were time to starting germination (TSG), time to maximum germination (TMG), time to 50% germination (T50%G) and percentage of seed germination (PSG). The putative causes of variation in germination, oil content (OC) and 1000 grain weight (1000GW) were also measured. Positive correlations were obtained between different times to germination for normal and stress conditions. Positive correlations were observed between PSG and OC, as well as between 1000 GW and the different times to germination. Several non-specific QTLs to water deficit were detected for germination parameters. “HA1837”, “SSL27“and “ORS671_1” were the SSR markers associated with QTLs detected for germination characters independent of germination environments. The most important specific QTL was associated with “ORS677” SSR marker in the water stress condition, explaining 24% of the phenotypic variance for PSG.

Hand pollination of G. hirsutum (2n= 4x= 52, AA D1D1) with G. arboreum (2n= 2x= 26, A1A1) produced 18.7% hybrid seeds. None of the hybrid seeds germinated in pots and in all likelihood the embryo (A1AD1) and the endosperm (A1AAD1D1) were incompatible. In vitro culture of ovules 5 days after pollination (DAP), failed to support the growth of viable embryos. Hybrid embryos 50 DAP, excised from field pollinated hybrid seeds, successfully germinated in vitro. Triploid hybrid plants were successfully grown to flowering in pots. The frequency of generation of hybrid plants was 2.3% of cultured embryos. Pollen mother cells of the hybrid plant showed the expected A genome ring of 4 and ring of 6 chromosomes. In addition, there were several unpaired chromosomes of the D genome at metaphase I. The unpaired chromosomes grouped randomly at MII and organized spindles around them. The mature pollen grains were sterile due to aneuploidy.