We conducted field experiments since 2006 to determine the effect of tillage practices and rate of nitrogen fertilization on soil properties and crop yield. Four tillage practices and five N rates were used. The results showed that the year-round total yield of wheat and maize under harrow tillage (HT) and rotary tillage (RT) was not significantly different from that of conventional tillage (CT, moldboard tillage) but was higher than that of no-tillage (NT). Reduced tillage (HT and RT) with straw returned and rate of nitrogen (157.5 kg/ha for wheat and 202.5 kg/ha N for maize) were suitable to increase the yield and adjust the soil carbon and nitrogen situation for the winter wheat-summer maize cropping system.

SUMMARYThe relationship between climate, crop growth and crop yield is complicated. This study aimed to determine the ratio of CO2–C emission to grain yield, the field treatments were initiated in 2003, but the measurements for this analysis were collected during the summer maize-growing seasons of 2011 and 2012 in the North China Plain. The experiment showed that conventional tillage with straw application significantly increased grain yield and the ratio of CO2–C emission to grain yield of summer maize. The mean soil CO2–C emission rate with no tillage was significantly lower than that when conventional tillage was used; however, straw application significantly increased the soil CO2–C emission rate, irrespective of whether tillage was performed or not. This was mainly because straw application changed the soil total porosity and organic carbon content. In conclusion, the results of this study support the hypothesis that the ratio of CO2–C emission to grain yield in the North China Plain can be increased by straw application, whereas no tillage decreases this ratio.

Maize (Zea mays L.) is usually planted at high density, so most of its leaves grow in low light. Certain morphological and physiological traits improve leaf photosynthetic capacity under low light, but how light absorption, transmission, and transport respond at the proteomic level remains unclear. Here, we used tandem mass tag (TMT) quantitative proteomics to investigate maize photosynthesis-related proteins under low light due to dense planting, finding increased levels of proteins related to photosystem II (PSII), PSI, and cytochrome b6f. These increases likely promote intersystem electron transport and increased PSI end electron acceptor abundance. OJIP transient curves revealed increases in some fluorescence parameters under low light: quantum yield for electron transport (φEo), probability that an electron moves beyond the primary acceptor QA− (ψo), efficiency/probability of electron transfer from intersystem electron carriers to reduction end electron acceptors at the PSI acceptor side (δRo), quantum yield for reduction of end electron acceptors at the PSI acceptor side (φRo), and overall performance up to the PSI end electron acceptors (PItotal). Thus, densely planted maize shows elevated light utilization through increased electron transport efficiency, which promotes coordination between PSII and PSI, as reflected by higher apparent quantum efficiency (AQE), lower light compensation point (LCP), and lower dark respiration rate (Rd).

A two-year field experiment was conducted to investigate the effects of colored polyethylene (PE) films on weed control, soil temperature and moisture, and pod yield of peanut. By setting a clear PE film (CF) as control, three colored PE films were studied: black-clear-black color-matching film (BCF), silver grey film (SF) and black film (BF). The colored PE films were effective in controlling weeds compared with CF, while BF had the optimal weed control effect. Compared with CF, the colored PE films were not sensitive to air temperature, and had smaller daily temperature variations. Soil moisture at 0-40 cm depth was higher mulched with the colored PE films than those with CF, and the highest moisture occurred in BF. Peanut covered colored PE films remained higher chlorophyll content and net photosynthetic rate in the late growth stage. Compared with CF, the pod yields with BCF, SF and BF were significantly increased by 12, 7, and 5% in 2012, and 14, 10, and 5% in 2013, respectively. The treatments of SF and BCF get higher yields in 2012 and in 2013. Accordingly, SF and BCF may be better field-management options for weed control and high yield in peanut field. Keywords 79Plant Soil Environ. Vol. 61, 2015, No. 2: 79-85 Experimental design. A randomized complete block design with three replications was used with four kinds of PE films mulching including clear PE film (CF) as control, black-clear-black color-matching film with the 25 cm clear band in middle of the film (BCF), silver gray film (SF), and black film (BF), all films are 0.008 mm thick and 90 cm width. Alternating ridges (50 cm wide and 15 cm high) and furrows (50 cm wide) were used with only the ridges mulched with film. Two rows of peanut were sown with two seeds in one hole in each ridge on 1 May 2012 and 4 May 2013 with 25 cm row-spacing and 16 cm seed spacing, and the density is 125 000 holes/ha. The peanut cultivar is Huayu 22. Each plot was 3 × 10 m 2 . The peanut was harvested on 8 September 2012 and 10 September 2013. Before ridging, 500 kg/ha of triple compound fertilizer (15% N-4.3% P-8.3% K) were applied, and there were no irrigation and herbicide during the whole growth period.Soil measurements. Soil temperatures at 5 cm and 10 cm depth were measured with thermometer during the pod setting and filling stage at 8:00, 14:00 and 20:00. At the same time, soil moisture was measured at 20 cm intervals to a depth of 40 cm by gravimetric method (Black 1965).Weed control assessment. The species and density of weeds were collected in 1 m 2 at three random locations per plot when peanut was harvested. All weeds were identified, counted and recorded for the species and density calculation referred to the China's farmland weed color map (Tang 1989). The total weed biomass was determined after drying at 105°C for 30 min initially and then at 75°C for 48 h (Zhang et al. 2011).Growth parameters. Photosynthesis rate was determined by using a portable photosynthesis meter (LI-6400XT, LI-COR, Lincoln, USA) at the four growth stages (flowering, ...

Fluorination vs. chlorination: a case study on high performance organic photovoltaic materials