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.
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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, ...
