不同保墒措施的综合评价

保墒措施是节水研究的重要内客。通过对三种不同保墒措施的比较表明:冬小麦以覆膜种植的产量和水分利用率最高,但美中不足是费用较高;玉米整株秸秆覆盖保墒效果明显,且材科来源广、费用低,两垅间以2株玉米秸秆覆盖为宜;喷洒蒸发抑制与对照比较效果不明显。

Effects of DPC on Agronomic Traits and Economic Characters of Machine-Harvested Cotton in the Yellow River Valley of China and Chemical Control Techniques

[Objective] The aim was to investigate the effects of DPC chemical controlling technique on agronomic traits, yield and quality of machine-harvested cotton in the Yellow River Valley of China, and clarify the reasonable control period and the application amount of DPC. [Method] The new machine-harvested cotton variety Hengmian HD008 was used as the test material, and 3 different DPC treatments were set. [Result] DPC significantly reduced plant height and branch length, reduced branch angle and leaf area, so the rational control can effectively shape the ideal plant type of machine-harvested cotton. DPC had significant effects on yield and yield components, and the proper amount of DPC could increase the number of bolls during hot days, the number bolls in autumn and the total number of bolls. It increased the boll weight and seed index, but decreased lint percentage decreased, and proper amount of DPC could increase the yield. DPC significantly increased the specific breaking strength of fibers, and proper control could improve the uniformity of fibers, but other indexes had no significant influence. [Conclusion] According to the requirements of machine harvest to the agronomic traits of cotton and the growth characteristics of cotton plant, chemical control could begin after floral bud emergence in cotton about every 10 d, and the spraying amount can be controlled according to the growth amount of the main stem. The daily growth amount of plant height should be controlled at 1.5-1.8 cm, and the plant height should be within 75-90 cm.

Breeding of Good-quality High-yield Salt-tolerant and Drought-resistant Hybrid Cotton Variety Hengyou 12

Salt and drought tolerance, high yield and quality, disease and pest resistance of cotton varieties are new requirements for the current situation in cotton production. Hengyou 12 is a transgenic Bt cotton variety bred by hybridizing JD 28 （interspeciflc progeny of upland cotton, sea-island cotton, wild cotton species） as female parent with GK55 （transgenic Bt cotton variety） as male parent. The combining of parents was based on the complementary principle of parental traits. Hengyou 12 with strong heterosis was selected under disease stress, pest stress, salt stress and drought stress. This variety has many excellent characteristics, such as good resis- tance to diseases and pests, high yield, excellent quality, strong drought resistance and salt tolerance. ＇Hengyou12＇ was approved by Hebei Province in 2015, and is suitable for planting in middle and south areas of Hebei and similar ecological areas in the Yellow River basin.

Comparative Study of Grain Filling Characteristics in Maize

Abstract This study was conducted to illustrate the differences in grain filling characteristics between different maize materials in the Northern area of Huanghuaihai Plain, to provide a theoretical basis for the breeding of maize varieties with suitable maturation stage. The new maize hybrid Hengzao 8 was selected as an experimental material, and varieties Huamei 1 and Zhengdan 958 were selected as CK. The changes in grain size, water content, dry weight and grain filling characteristics during grain filling process were studied, and the yield components were analyzed. The grain sizes of the 3 maize materials increased rapidly within 20 d after pollination and reached their peak values on the 45^th d after pollination. Hengzao 8 had the biggest grains, while Zhengdan 958 showed the smallest grains. The 3 maize materials showed high growth speeds of dry matter from the 15^th to the 55^th d after pollination, Hengzao 8 being the fastest and Zhengdan 958 being the slowest. The growth speeds of grain dry matter dropped afterwards. The grain filling rates of the 3 materials fit the unimodal distribution; and Hengzao 8 presented the highest peak value, while Zhengdan 958 exhibited the lowest peak value. Grain size was positively correlated with water amount and negatively correlated with water content, and the grain filling rate was positively correlated with water amount. Regression analysis revealed that when the water contents of the 3 materials reached 57%, grain filling rates reached their peak values. The Logistic model showed that the maximum grain filling rate （Gmax） and the mean filling rate （Gmean） were higher in Hengzao 8 whose active grain filling stage, early stage （T1） , middle stage （T2） and late stage （T3） were shorter than other 2 varieties. The differences in 1 000-grain weight between the 3 materials were responsible for the differences in the yield. The grain filling characteristics of Hengzao 8 are decisive for achieving early maturation and high yield.