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Under the condition of pot cultivation in the field, the intelligent ultra-low temperature light incubator was used to carry out a 4h·d−1 simulation experiment of late spring coldness in the anther differentiation period of two wheat varieties, Yannong 19 (YN19, strong resistance to late spring coldness) and Xinmai 26 (XM26, weak resistance to late spring coldness). Two temperature treatments of 2℃ and −2℃ were set, and the control treatment (CK) was 10℃, in order to clarify the effect of different degrees of late spring coldness on the number of grains and grain weight at different spike positions of wheat main stem. The results showed that: (1) the number of fertile grains and grain weight at different spikelet on the main stem in different treatments were changed as a quadratic curve of first increased and then decreased. (2)Late spring coldness significantly reduced the number of fertile grains at different spikelet and grain positions of wheat main stem, and the reduction amplitude increase with the increase of stress degree. Under 2℃ and −2℃ treatment, the total fertile grains of lower, middle and upper spikelets of YN19 decreased by 40.74%, 18.75%, 35.00% and 70.37%, 32.50% and 15.00% respectively, while XM26 significantly decreased 62.50%, 7.87%, 20.00% and 100%, 42.22%, 100%, respectively. (3)Mild late spring coldness stress (2℃) reduced the grain weight of wheat main stem, while severe late spring coldness stress (−2℃) increased the grain weight due to the sharp reduction of the number of grains per spike. Compared with CK, the grain weight of spikelets of YN19 decreased by 2.93% − 47.53% and XM26 by 19.72% − 49.96% under 2℃ low temperature stress treatment; the grain weight of spikelets of YN19 increased by 20.57% − 60.84% and XM26 by 1.20% − 42.78% under −2℃ low temperature treatment. (4)The dry weight of the total grains at different parts of wheat main stem spike in two varieties was lower than that of CK due to the late spring coldness. Under the stress of 2℃ and −2℃, the dry weight of total grains of the lower and middle spikelets of YN19 significantly decreased by 49.49%, 28.99% and 65.76%, 29.47%, respectively, compared with CK, and the dry weight of total grains of the upper spikelets under −2℃was significantly reduced by 23.09% compared with CK. While under the stress of 2℃ and −2℃, the dry weight of total grains of the lower, middle and upper spikelets of XM26 significantly decreased by 69.76%, 28.61%, 20.02% and 100%, 42.33%, 100%, respectively, compared with CK. To sum up, the late spring coldness had adverse effects on the number of fertile grains and grain weight at different spikelet and grain positions of wheat main stem. The damages to the wheat main stem spike position was shown as follows: the lower spikelet > the upper spikelet > the middle spikelet, and the order of damage to the wheat grain position was shown as follows: G3 (the third grain position) > G1 (the first grain position) > G2 (the second grain position). It was concluded that the effect of late spring coldness on the number of fertile grains was greater than on the grain weight, and the degree of influence increased with the aggravation of late spring coldness stress. Both the number of fertile grains and the weight of grains showed that the lower spikelets were most affected, that is, the inferior spikelets and inferior grains were more affected by the late spring coldness. The late spring coldness during the anther differentiation period mainly reduced the number of grains per spike of the upper spikelet and the lower spikelet of the main stem spike, reduced the weight of inferior grains, and finally leads to the reduction of wheat yield. By comprehensive comparison, the damage degree of YN19 was less than that of XM26, and YN19 had stronger resistance to late spring coldness. Therefore, selecting wheat varieties with strong resistance to late spring coldness is an important measure to reduce the damage of late spring coldness in wheat production. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The dry-hot wind stresses of high temperature resistant wheat variety of Jimai 22 was conducted with a self-developed portable dry-hot wind generation simulator, the air temperature, humidity and wind speed in the simulation box were controlled by the central control system to simulate the intensity and process of dry-hot wind. According to the Meteorological Industry Standards of QX/T 82-2007 of the People's Republic of China, two stress levels, as severe diy-hot wind （S） and mild dry-hot wind （M） were compared, that were based on the air temperature, relative humidity and wind speed. Two stress stages as the middle filling stage （13 days after flowering） and the later filling stage （23 days after flowering） were all condidered M and L. The distribution characteristics of grain weight at different spikelets and grain positions, and the relations to the stress degrees were all researched under different stages and levels of dry-hot wind stresses, to provide theoretical basis for the prevention and control of dry-hot wind disasters. The results showed that the grain weights at spikelet and grain positions on main stem and tiller in different treatments were changed as a quadratic curve of first rising and then decreasing. A significant decreases were observed under different dry-hot wind stresses. The total grain weights of the lower and upper parts of the spikes were sharply reduced during the middle filling stage, the damages to grain weights were showed as follows: G3 (the third grain position)〉G1 (the first grain position)>G2 (the second grain position). The grain position of G3, G1 and G2 indicated that the grains were developed from florets of the third, first and second positions respectively. While the grain weights of the lower and middle parts of wheat ear were severely reduced at the later stage stress, and the damage in G3 position was greater than that of the G2 and Gl. It was concluded that under such simulation condition, the more significant decrease was observed in the grain weight of the tiller ear in the middle filling stage of dry-hot wind, while the damage to the grain weight of the main stem spike was more serious in the later filling stage. The decrease of the grain weight at the G3 grain position was the most prominent under the middle and later stage stress. The effects of dry-hot wind on grain weights in the middle stage of grain filling were greater than those in the later stage, and the effects of severe dry-hot wind stress were also larger than those of mild stress. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

By using FACE (Free-Air Controlled Environment)-ozone system, a field plot experiment was conducted in 2008-2009 to study the effects of elevated ozone (O3) concentration on the flag leaf microscopic structure, chlorophyll content, and grain weight of wheat. Two treatments were installed, i. e. , ambient O3 and 150% of ambient O3, and four winter varieties, i. e. , Yannong 19, Yangmai 16, Jiaxin 002, and Yangfumai 2, were taken as the test materials. At anthesis, elevated O3 concentration had a slight damage to the flag leaf microscopic structure. The mesophyll cell and chloroplast structure began destroying, and the grana lamellae started breaking and loosing. Twenty-one days after anthesis, the differences in the leaf microscopic structure between the two treatments became significant. Under elevated O3, the flag leaf senescence was accelerated, with the endomembrane system disintegrated, grana lamella disappeared, and corpus adiposum inside chloroplast broken down, resulting in a significant decrease of the chlorophyll content, photosynthesis rate, and grain weight at maturing stage. Significant difference was observed among the test varieties in their responses to elevated O3. Jiaxin 002 was tolerant, while Yangfumai 2 was sensitive to the ozone stress. [ABSTRACT FROM AUTHOR]

By the method of yield component, a simulation model on barley yield formation was established, which could be available for different barley cultivars in different areas. The establishment process of the model was as the following. With the yield components of different cultivars under optimal conditions in Wuhan, Yangzhou, and Kunming as the bases, the regression equations of the relative values of ears per plant, kernels per ears, and thousand-grain weight with the accumulated photosynthetic effective radiation (ΣPAR) were established, and the functional relations between the ears per plant, kernels per ears, and thousand-grain weight under actual conditions as well as their potential values under optimal conditions and the variables soil moisture regime and nutrient contents under actual conditions were formed. The model more comprehensively considered the internal and external factors of barley growth and development. The internal factors reflecting the genetic properties of cultivar included potential ears per plant, potential kernels per ear, potential thousand grain weight, and grain-filling duration; while the external factors included ΣPAR and soil moisture regime and nutrient contents. Field experiments with different barley cultivars at different sowing dates were conducted in Wuhan, Kunming, and Yangzhou, and the data obtained were used to calibrate and validate the model. The results showed that the model better simulated the yield components and theoretical yield, with the average absolute values of relative error (RE) of ears per plant, kernels per ear, and thousand-grain weight being 196%, 188% and 167%, respectively. The correlation coefficient from y=x regression analysis on the simulated and observed values of the three yield components and theoretical yield was between 09464 and 09987, indicating that this model was more predictable and applicable. [ABSTRACT FROM AUTHOR]