[Correlation between nitrogen fruiting efficiency and nitrogen utilization and remobilization in winter wheat at different sowing dates]. / ä¸åŒæ’­æœŸå†¬å°éº¦æ°®ç´ å‡ºç±½æ•ˆçŽ‡ä¸Žæ°®ç´ åˆ©ç”¨åŠè½¬è¿çš„ç›¸å ³æ€§.

To understand the correlation between nitrogen fruiting efficiency and nitrogen utilization and remobilization in winter wheat, the differences and mutual relationships of nitrogen fruiting efficiency, nitrogen utilization and remobilization of winter wheat at different sowing dates (S1:24 September, S2:1 October, S3:8 October, S4:15 October and S5:22 October) were analyzed in two growing seasons from 2014 to 2016. The results showed that there was no significant difference in grain yield and grain number per unit area among different sowing dates. Delayed sowing date decreased nitrogen accumulation in both shoots and spikes, and then reduced nitrogen uptake efficiency and increased nitrogen utilization efficiency and nitrogen fruiting efficiency. Nitrogen fruiting efficiency was positively correlated with nitrogen utilization efficiency, negatively correlated with nitrogen uptake efficiency, but not significantly correlated with nitrogen use efficiency. Nitrogen nutrition index tended to be optimum with delayed sowing dates, showed synchronicity with the improvement of nitrogen fruiting efficiency. Pre-anthesis nitrogen remobilization amount in vegetative organs and post-anthesis nitrogen accumulation amount significantly decreased with postpone of sowing dates, but pre-anthesis nitrogen remobilization efficiency remarkably rise. There was a positive correlation between nitrogen fruiting efficiency and nitrogen remobilization efficiency, indicating that the improvement in nitrogen remobilization efficiency facilitated the increment in nitrogen frui-ting efficiency. Taken together, properly delayed sowing date reduced nitrogen uptake, but increased nitrogen utilization efficiency and nitrogen fruiting efficiency and improved nitrogen supply status, which provided a theoretical basis for the implementation of reducing input and improving nitrogen utilization efficiency in wheat production in this region.

[Stability of a winter wheat population with high yield and high resource use efficiency]. / å†¬å°éº¦é«˜äº§é«˜æ•ˆç¾¤ä½“çš„å¹´é™ é—´ç¨³äº§æ€§èƒ½.

Using the winter wheat cultivar Tainong 18 as the experimental material, we analyzed yield stability from 2012 to 2016 under three different treatments: T1(following typical local field management practices), T2(high-yield: high nitrogen and water were supplied to foster high grain yield), and T3(high-yield, high-efficiency: optimized field management including increasing plant density, reducing nitrogen input and delaying of the sowing date). Yield related phenotypic traits, including the number of ears on the main stem and tillers, leaf area index (LAI), photosynthetically active radiation (PAR) interception, dry matter accumulation and distribution, as well as grain yield, were analyzed over four seasons to determine their relationships with annual radiation, accumulated temperature and precipitation. We then determined grain yield stability for each of the three treatments. The amount and distribution of radiation, accumulated temperature, and precipitation varied greatly within each season. The ears on the main stem represented 38.9%, 58.7%, and 66.9% of the total ears, respectively, for wheat grown in the T1, T2 and T3 treatments, indicating that T1 ears originated mainly from the tillers, T2 ears from both the main stem and the tillers, and T3 ears from the main stem. The T2 and T1 treatments produced the highest and lowest amount of dry matter and grain yield, respectively. Although having relatively lower dry matter accumulation at maturity compared with T2, T3 led to higher grain yield due to high LAI, high PAR interception and utilization, high net canopy photosynthetic rate from booting (especially from 14 days after anthesis) to maturity and a higher harvest index. Among the three treatments, T3 resulted in the lowest annual range, standard deviation, and coefficient of variation for LAI, PAR interception, and dry matter accumulation. Thus, grain yield was most stable in wheat grown in the T3 treatment mainly due to stability in biological production during all four seasons.

[Characteristics of farmland eco-environment at the intercropping stage of maize intercropped with winter wheat and their effects on seedling growth of summer maize].

To study the farmland eco-environment of intercropping maize with wheat at the intercropping stage and its influence on maize seedling growth, two summer maize cultivars, Zhengdan 958 and Denghai 661, were either intercropped with wheat or directly seeded. The result demonstrated that there was little difference for the soil water content of the farmland between the two cultivation methods. The highest soil temperature of intercropped maize was 4.8-5.2 °C lower than the soil temperature of directly-seeded maize, and the lowest temperature of the intercropped maize was 1.4-1.7 °C lower. But, the temperatures for both planting methods met the requirement for seed germination. Light intensity on the ground surface of the intercropped maize was 4.4%-10.6% less than natural light, and insufficient light was the main reason for the weak and late seedling. Compared to the directly-seeded maize, the speeds of seed germination and accumulation of dry matters of the intercropped maize were relatively slow. On the whole, the seedling of intercropped maize was not strong, which presented small leaves, short height and low chlorophyll content. The restraint on the growth of intercropped maize was enhanced with the extension of intercropping period. For farm planting, direct-seeding could improve the seed germination and seedling growth of summer maize.

[Effect of plant density on population yield and economic output value in maize-soybean intercropping].

The effects of plant density on population yield and economic output value in maize and soybean intercropping were studied with the design of the double saturated D-optimal regression. A mathematical model was developed, in which the densities of maize and soybean were independent variables, and population grain yield, dry matter accumulation and economic output value were dependent variables, respectively. The result showed that the plant density significantly affected the population grain yield, dry matter accumulation and economic output value, and the effects of density of maize on population indices were greater than those of density of soybean. Under the low level conditions of density, the population grain yield, dry matter accumulation and economic output value increased with the density of maize and soybean. The maximum population grain yield was 8101.31 kg · hm(-2) the optimized combination of 72023 plant maize · hm(-2) and 99924 plant soybean · hm(-2), while the maximum population dry matter accumulation was 15282.45 kg · hm(-2) with the optimized combination of 75000 plant maize · hm(-2) and 93372 plant soybean · hm(-2), and the maximum population economic output value was 23494.50 Yuan · hm(-2) with the optimized combination of 73758 plant maize · hm(-2) and 87597 plant soybean · hm(-2). The optimum combination of densities of maize and soybean calculated by computer were 58554-71547 plant · hm(-2) for maize and 82217-100303 plant · hm(-2) for soybean in order to obtain grain yield greater than 7500 kg · hm(-2), dry matter accumulation greater than 14250 kg · hm(-2) and economic output value greater 22500 yuan · hm(-2) under the condition of this experiment.

[Effects of cropping patterns on photosynthesis characteristics of summer maize and its utilization of solar and heat resources].

In order to investigate the effects of interplanting and direct seeding on the photosynthesis characteristics of summer maize and its utilization of solar and heat resources, two summer maize cultivars (Zhengdan 958 and Denghai 661) were planted in the farmlands of Denghai Seed Co. Ltd in Laizhou City of Shandong Province, with 67500 plants x hm(-2) and three sowing dates. The above-ground biomass, plant growth rate, leaf area index, and net photosynthetic rate per ear leaf were measured to reveal the photosynthesis characteristics of test cultivars. In the meantime, the characters of grain-filling were simulated by Richards' model, and the solar resource utilization efficiency of the cultivars was calculated, in combining with meteorological data. Comparing with interplanting, direct seeding increased the grain yield by 1.17%-3.33%, but decreased the thousand-grain weight significantly. Growth stages were extended under earlier sowing. The leaf area index and net photosynthetic rate from flowering to 30 d after anthesis were significantly higher under direct seeding than under interplanting, but after then, they decreased faster. Direct seeding induced a higher accumulation of dry matter and a faster plant growth rate before and after flowering. Under direct seeding, the maximum grain-filling rate reached earlier, the starting potential was higher, but the grain-filling period, active grain-filling period, and W(max) were lower, compared with those under interplanting. Also under direct seeding, the total accumulative temperature and solar radiation during growth period decreased by 150-350 degrees C x d and 200-400 MJ x m(-2), respectively, but the solar resource utilization efficiency of grain increased by 10.5%-24.7%. All the results suggested that direct seeding was superior to interplanting for the summer maize production under field condition. In order to enhance solar and heat utilization efficiency and excavate yield potential, it would be essential to improve the leaf photosynthesis efficiency and postpone leaf aging.