Effects Of Black Plastic Film Mulching On Growth And Yield In Peanut (Arachis Hypogaea L.)

Through shading treatment in pot-cultivation experiments and mulching black plastic film treatment in field experiments, this article studied the role of light in hypocotyl elongation and the effects of black film on the growth and yield in peanut. The main results were as follows:1. Black plastic film mulch improved the ecological environment of cultivation layer (0-20cm) in peanut field. It increased soil temperature and reducing water evaporation. The raise function of plastic film to soil temperature was less and less along with the depth of soil in the range of 0-20cm and along with the growth and development of peanut. Among the three film-covering treatments, white transparent film could increase the soil temperature the most and two layers of black films increased it the least.2. In the pot-cultivation experiments, it was found that peanut's hypocotyl was elongated obviously by shading during its germination stage. Moreover, the worse it was shaded, the more its hypocotyl was lengthened. Shading enhanced the content of IAA and ZR, reduced that of GA3 and ABA in hypocotyls, and then destroyed the balance of hormones in peanut plant. In detail, IAA/ABA and ZR/ABA were increased, while GA3/ABA was decreased. It was found after analysis that the length of hypocotyls had a positive correlation with the content of IAA and ZR, IAA/ABA, ZR/ABA, and GA3/ABA in hypocotyls, a negative correlation with the content of GA3 and ABA, and a significant positive correlation with ZR/ABA.3. Black film mulch postponed the exposure of hypocotyls and cotyledon to light, elongated hypocotyls length, unearthed more cotyledons, and accelerated the growth of lateral branch. The rate of cotyledons unearthing is 56.40% in no mulch treatment. This rate was increased 17.12% and 30.66% respectively in the mulch treatments of one layer black film and two layers black films.4. Black plastic film mulch accelerated the growth of peanut, prolonged the yield forming phase, especially pot mature phase. The pot mature phase in no mulch treatment was 17.84 days, and it was increased 9.25, 7.23 and 5.81 days in thetreatments of two layer black films, one layer black film, and white transparent film respectively.5. Mulch decreased the height of main branch and the length of the first pair of lateral branches, increased their diameters, added total blossom per plant and peanut pins, but induced the number of pins that entered into the soil. The dry matter accumulation of the upper plant was accelerated and increased, which was propitious to the development of peanut pods. Root dry matter accumulation was enlarged by mulch in the late growth stage, and therefore, the senescence of leaves was delayed and the leaves area index was enhance. The swelling rate of peanut pods was increased by mulching film, especially black film.6. Mulch influenced greatly the diurnal changes of photosynthesis rate and fluorescence parameters in the late growth stage of peanut. Pn, Fv/Fm, OPS II, qP and NPQ was always higher in mulch treatments than in no mulch treatment. In mulch treatments Pn showed a two-peak diurnal changes curve, falling at noon, and the two peaks appeared at 11h and 15h respectively; while it showed a one-peak diurnal changes curve, never climbing up after the peak, and the peak appeared at 11h.7. The yield of peanut was increased by mulch treatment. The order of yield was: one layer black film > two layers black film > transparent film > no mulch treatment. There was a significant correlation between mulch treatments and no mulch treatment, one layer black film and transparent film.