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High salinity interferes in sugarcane growth and development, affecting not only crop yield but also reducing sucrose concentration in culms. Sugarcane plants submitted to salt stress can accumulate compatible solutes, such as proline, which may counteract the effects of salt accumulation in the vacuole and scavenge reactive oxygen species. The objective of this study was to evaluate the response to salt stress of sugarcane plants transformed with the Vigna aconitifolia P5CS gene, which encodes Δ1- pyrroline-5-carboxylate synthetase, under the control of a stress-induced promoter AIPC (ABA-inducible promoter complex). For this, 4-month-old clonally multiplied sugarcane plants from two transformation events were irrigated every 2 days with 1/10 Hoagland’s solution supplemented with 100, 150 and 200 NaCl, progressively, during 28 days. Transgenic lines showed increased transgene expression in 3.75-fold when compared with the control plants after 9 days of irrigation with saline water, which can explain the higher proline concentration found in these plants. At the end of the experiment (day 28), the transgenic lines accumulated up to 25 % higher amounts of proline when compared with non-transformed control plants. Stress response in transgenic plants was also accompanied by a reduction of malondialdehyde (MDA) derived from cellular lipid peroxidation in leaves, lower Na⁺ accumulation in leaves and maintenance of photochemical efficiency of PSII. Thus, proline contributed to the protection of the photosynthetic apparatus and the prevention of oxidative damage in transgenic sugarcane under salt stress.
Allene oxide synthase (AOS, EC 4.2.1.92) is the first specific jasmonate biosynthetic pathway gene. In this study, a full-length cDNA of AOS gene was cloned from common wheat nannong 9918. The gene contains an open reading frame (1,446 bp) encoding 418 amino acids. Comparative and bioinformatic analysis revealed that the deduced protein of TaAOS was highly homologous to AOSs from other plant species. The transcript of TaAOS was found to be abundantly expressed in the flag leaves, and was up-regulated by the inoculation of B. Graminis (DC.) E.O. Speer f. sp. Tritici (Bgt) in wheat leaves. In addition, it was also induced by high concentration of NaCl and ZnCl₂. When TaAOS was overexpressed in tobacco leaves via Agrobacterium tumefaciens infection, the transgenic tobacco plants displayed stronger tolerance to ZnCl₂ stress compared to transgenic GFP plants. Taken together, the above facts demonstrated that TaAOS may play a role in response to diverse stresses in plants.
Valerian (Valeriana officinalis L.) is a medicinal plant, but its cultivation is restricted by weed competition. Therefore, three rates (0.75X, 1X, and 1.25X, where X is equal to the recommended dose of haloxyfop-R (methyl ester), sethoxydim, oxadiargyl, bentazon, oxadiazon, and oxyfluorfen) were applied at the 3–4 leaf stages to valerian plants. This application was done to select the herbicide type and rate for post-controlling broadleaf and grasses weeds in this species. Herbicide injury, Soil-Plant Analyses Development (SPAD) reading, number of leaves per plant, stem diameter, and fresh and dry weights were determined 10, 20, and 30 days after herbicide application. Oxyfluorfen application caused the most herbicide injury followed by bentazon. Injury increased as the rate and the days after application increased. Oxadiazon only caused significant damage 30 days after application under all three rates. Other treatments showed no marked injuries under any rate or date after application, as compared with the control. Effects on other measured traits depended on the trait, herbicide, and herbicide rate. The highest SPAD, leaf number, shoot diameter, fresh weight and dry weight, was recorded under application of 30 mg a.i. ∙ kg–1 soil oxadiargyl and 90 mg a.i. ∙ kg–1 soil oxadiazon, 81 mg a.i. ∙ kg–1 soil haloxyfop-R, 37.5 mg a.i. ∙ kg–1 soil oxadiargyl, 22.5 mg a.i. ∙ kg–1 soil oxadiargyl, 81 mg a.i. ∙ kg–1 soil haloxyfop-R, and 81 mg a.i. ∙ kg–1 soil haloxyfop-R, respectively. To sum up, the results showed that sethoxydim, oxadiargyl, and haloxyfop-R produced no significant symptoms of phytotoxicity or reduction of measured traits. This means that oxadiargyl, haloxyfop-R, and sethoxydim may be used safely for weed control of valerian at the rates used in this experiment under similar conditions.
Six-week old sunflower seedlings, cv. Ogrodowy, were treated with 0, 15, 45 and 60 mg Pb dm-3, and then the content of lead and selected physiological and biochemical parameters were measured. Photosynthesis efficiency, water relations (intensity of transpiration, relative water content (RWC)) and gene-encoding metallothionein were measured three times after 24, 48 and 72 hours of exposure to Pb. The content of glutathione and lead was analysed after 72 hours’ exposure to Pb. Most of the lead uptake was accumulated in the roots, then in the stems and leaves, but when re-calculated per plant dry weight, the uptake of the metal did not depend on the lead dose applied. The highest 60 mg Pb dm-3 treatment was accompanied by a significant decrease in dry weight content. Moreover, most of the lead taken up in these plants was transported to the stems and leaves (23.6% of total lead uptake). The lead doses used in this study did not affect the intensity of photosynthesis, but a decrease in transpiration and relative water content was observed. The glutathione level in the plants varied depending on the organ examined and the Pb concentration in the treatment. The expression of the metallothionein gene HaMT1 was observed in the stems only. These results indicate that the sunflower cultivar Ogrodowy is a promising plant for phytoremediation of lead-polluted soils.
A pot study was conducted in net house to determine the influence of hormonal priming kinetin (50 mg·dm-3), salicylic acid (50 mg·dm-3), spermine (50 mg·dm-3) and spermidine (50 mg·dm-3) on emergence, yield, antioxidants and ionic content of two wheat (Triticum aestivum L.) cultivars SARC-1 (salt tolerant) and MH-97 (salt sensitive) under normal and saline conditions. The growth of wheat plants was severely affected by salinity stress. But the most of hormonal priming strategies were effective in alleviating the adverse effects of salt stress on wheat plants, however, hormonal priming with salicylic acid (SA) followed by priming with kinetin successfully enhanced seedling vigor by increasing emergence index, decreasing the uptake of Na+ and finally increasing grain yield of both cultivars under normal as well as saline conditions. Activities of SOD and CAT in both cultivars were significantly affected by priming in stressful environment. On the other hand, SARC-1 performed better as compared to MH-97 due to the increased antioxidant activities under salt stress. It can be concluded that priming with 50 mg·dm-3 SA followed by 50 mg·dm-3 kinetin for 12 h maximally improved salt tolerance in both wheat cultivars.
Chilling stress is of major limiting factors influencing the growth and development of warm-season crops like cucumber. In this research, the possibility of chilling tolerance of cucumber seedlings was investigated through employing the drought and low-temperature pretreatments. The factorial experiment consisted of two factors including cucumber cultivars (i.e. ‘Super Dominos’ and ‘Super Star’) and hardening treatments (control, low temperatures at 10°C, and 15°C and drought simulated by 10% and 20% PEG) based on completely randomized design (CRD) in 3 replications. After applying treatments and providing them 48 h opportunity to be recovered, the seedlings were subjected to 3°C for a six-day period and 6 h for each day. All hardening treatments improved seedlings’ growth, chlorophyll content, total phenol (TP) and antioxidant enzyme activities, while reducing chilling injury index and malondialdehyde (MDA) content. Comparing to temperature hardening, the drought pretreatment showed to have a better effect on inducing the chilling tolerance into cultivars. Overall, the results of this experiment showed that employing drought and low-temperature pretreatments enabled cucumber seedlings to mitigate the harmful effects of chilling.
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Badania dotyczące fitotoksyczności chlomazonu w postaci dwóch formulacji: herbicydu Command 480 EC i chlomazonu immobilizowanego w alginianowych kapsułkach w stosunku do roślin rzepaku przeprowadzono w kontrolowanych warunkach. Stwierdzono, że rośliny rzepaku, odmiany Bellevue, wykazują większą tolerancję w stosunku do chlomazonu immobilizowanego w hydrożelowej matrycy alginianowej niż do standardowej formy użytkowej tego herbicydu. Chlomazon w formie herbicydu Command 480 EC istotnie zmniejszył zawartość chlorofilu a, b, a+b oraz całkowitą zawartość karotenoidów. Zaobserwowano również istotnie ujemny wpływ chlomazonu, w formie środka Command 480 EC, na efektywność aparatu fotosyntetycznego rzepaku.
This study was conducted to determine the correlation between of salinity stress on growth and phenolic compounds in rice. It was observed that salinity stress caused a significant decrease in shoot lengths, fresh and dry weights of all rice varieties. Under salinity stress, changes of chemical contents also differed among phenolic compounds and rice cultivars. Total phenolics and flavonoids, and contents of vanillin and protocatechuic acid in tolerant varieties were strongly increased, whereas in contrast, they were markedly reduced in the susceptible cultivar. Ferulic acid and p-coumaric acid were detected only in tolerance rice. Vanillin and protocatechuic acid may play a role, but ferulic acid and p-coumaric acid may be much involved in the tolerant mechanism against salinity stress. Ferulic acid and p-coumaric acid and their derivatives are potent to be exploited as promising agents to reduce detrimental effects of salinity stress on rice production.
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