Photosynthetic traits are affected by many environmental factors, of which the most important ones are microclimate of crop stand and meteorological conditions. A 2-year field study was conducted to determine the photosynthetic rate (P) and chlorophyll index (SPAD) alteration in various spring barley cultivars throughout development stages under field conditions. The tests involved three seed rates (SR) [200 (SR I), 400 (SR II), and 600 (SR III) viable seeds per m2] and three cultivars (Aura DS, Barke, and Gustav). The measurements were made four times during the growing season. In 2008, the P values were the greatest at BBCH 45 under warm conditions coupled with a lack of rainfall. The spring barley cultivars differed in tolerance of the weather conditions between the experimental years. The P of Barke was the greatest in warm and dry conditions (2008), and that of Gustav was greatest mainly in wet conditions. The P of Aura DS was lower than the trial mean in both years. The SRs effect on P and SPAD was significant only in sporadic cases. The variation of P and SPAD depended significantly (P ≤ 0.05, P ≤ 0.01) on the weather factors and their interaction. 相似文献
Abstract From a field experiment in which wheat was supplied with nitrogen fertilizer at 0, 20, 40, 60, 80, 100, 150, 200, or 400 kg ha‐1N, a correlation existed between nitrate concentration in wheat stems at tillering and subsequent grain yield. At early tillering, NO3‐N concentrations around 8,000 μg g‐1 were indicative of sufficient nitrogen in the crop‐soil system for maximum grain yield. Averaging the results of this experiment with those from another seven field experiments, it was concluded that at tillering, the prognostic levels of NO3‐N concentration in stems were: below 4000 μg g‐1 deficient, between 4000 and 6000 μg g‐1 intermediate, between 6000 and 10000 μg g‐1 sufficient and above 10000 excessive for maximum grain yield. These values are applicable in a wide range of water supply conditions and to a number of cereal genotypes. 相似文献
Nitrate reductase activity (NRA) was studied in pea, a C3 plant, and sorghum, a C4 plant, at various stages of growth and development. Influence of moisture stress and nitrogen application was also observed since these factors have profound influence on growth and development.
In pea, NRA was maximum at pod maturity stage and minimum at flowering stage. In sorghum plant there was gradual increase in NRA upto grain formation followed by a fall in activity at maturity.
Nitrogen treatment as nitrate and ammonia significantly increased nitrate reductase activity over control in both pea and sorghum. Treatment with potassium nitrate was found to stimulate more NRA in pea than with ammonium sulphate. In sorghum, both forms of nitrogen did not differ much in their influence on NRA.
Influence of moisture stress in reducing NRA was more clear in sorghum, a C4 plant than in pea, a C3 plant. In general, control plants recorded low NRA in both the crops when compared to nitrogen treated plants except at pod formation stage in pea. 相似文献
The excretion of phytosiderophores by barley (Hordeum vulgare L.) has recently been documented and a major difference in the Fe‐stress response of gramineous species and dicotyledonous species proposed. However, currently used methods of quantifying and measuring phytosiderophore are tedious or require specialized equipment and a cultivar easily accessible to U.S. scientists is needed. The objectives of this study were (a) to determine if “Steptoe”; and “Europa”; (used as a control cultivar) barleys would release Fe3+ solubilizing compounds in response to Fe‐deficiency stress and (b) to develop a technique to determine the efficiency of solubilization of Fe(OH)3 by the released chelating substances. Two cultivars of barley were place under Fe‐stressed (‐Fe) and nonstressed (+Fe) conditions in modified Hoagland solutions (14 L). The solutions were periodically monitored for H+ and reductant release from the roots and plants were rated daily for chlorosis development. Periodic (6 or 7 harvests) evaluation of the release of Fe3+ solubilizing substances was performed as herein described. Neither H+ nor reductant extrusion occurred with either cultivar during Fe stress. However, Fe3+ solubilizing substances were released by both cultivars at relatively high levels under Fe‐stress conditions compared to the nonstressed plants. A convenient technique was developed to measure the release of Fe solubilizing substances released by barley roots. 相似文献
Low phosphorus (LP) limits crop growth and productivity in the majority of arable lands worldwide. Here, we investigated the changes in physiological and biochemical traits of Tibetan wild barleys (Hordeum vulgare L. ssp. spontaneum) XZ99 (LP tolerant), XZ100 (LP sensitive), and cultivated barley ZD9 (moderately LP tolerant) under two phosphorus (P) levels during vegetative stage. These genotypes showed considerable differences in the change of biomass accumulation, root/shoot dry weight ratio, root morphology, organic acid secretion, carbohydrate metabolism, ATPase (Adenosine triphosphatase) activity, P concentration and accumulation under LP in comparison with CK (control) condition. The higher LP tolerance of XZ99 is associated with more developed roots, enhanced sucrose biosynthesis and hydrolysis of carbohydrate metabolism pathway, higher APase (Acid phosphatase) and ATPase activity, and more secretion of citrate and succinate in roots when plants are exposed to LP stress. The results prove the potential of Tibetan wild barley in developing barley cultivars with high tolerance to LP stress and understanding the mechanisms of LP tolerance in plants. 相似文献
We conducted a five-year survey (2011–2015) of barley and wheat fields in Paraná state, Brazil, obtaining 754 Fusarium isolates from spikes with fusarium head blight (FHB)-symptoms. Multilocus genotyping and TEF-1α gene sequence analyses confirmed the dominance of the F. graminearum species complex (FGSC, 75.7%), but F. poae (11.5%), as well as F. avenaceum and related members of the F. tricinctum species complex (FTSC, 8.1%) appeared as substantial contributors to FHB. Within the FGSC, F. graminearum of the 15-ADON genotype was dominant (63%), followed by F. meridionale of the NIV genotype (23.1%), F. cortaderiae of the NIV (7%) or 3-ADON (2.6%) genotypes, and F. austroamericanum (3.8%) of the 3-ADON genotype. Substantial variation in pathogen composition was observed across years, with F. poae and F. meridionale frequencies significantly elevated in some years. Most F. poae strains produced DAS, diANIV, and butenolide, but not neosolaniol, T-2, or HT-2. All FTSC species produced moniliformin. Enniatin production was widespread among FTSC species, with the single F. acuminatum strain found to be the strongest producer of enniatins. Our findings confirm FGSC as a major contributor to FHB and expand considerably our knowledge of the presence, frequency, and conditions under which other pathogens may emerge, altering the spectrum of toxins that may accumulate in grain. 相似文献