Effects of Different Topdressing Conditions on Photosynthetic Characteristics and Yield for Peanuts under Mulched Drip Irrigation

The cropping patterns as drip irrigation under mulch were assumed in the experiment with peanut variety "Fu Hua 17" to study the effects of different topdressing on photosynthetic characteristics and yield for peanuts. Five different treatments were carried out to determine the photosynthetic characteristics, and a comprehensive evaluation was made in combination with the yields. The results showed that the diurnal changes for T1 (PK+Ca) and T2 (N+Ca) in the photosynthetic rate were lower than those in T3 (N+PK) and T4 (N+PK+Ca), a fact illustrating that N, P and K elements have a direct impact on peanut photosynthetic rate, chlorophyll SPAD value of the three treatments continued to decline at the beginning of flowering, which means that leaf chlorosis and fertilizer shortage appeared earlier for peanuts in the middle and late period. The sequence of yield was: T4 (N+PK+Ca) > T3 (N+PK) > T2 (N+Ca) > T1 (PK+Ca) > T5 (CK without topdressing). T4 yield was slightly higher than T3, a result showing with sufficient NPK, increasing Ca fertilizer could increase yield and efficiency. The studied results could offer theoretical basis for revealing the yield increasing mechanism of integrated management of water and fertilizer under mulched drip irrigation. Keywords-peanut; drip irrigation; photosynthetic characteristics; yield The peanuts production mainly depends on photosynthesis, and peanuts photosynthesis capacity is not only related to their own intrinsic factors, but also related to such external factors as illumination intensity, CO2 concentration, temperature, humidity, fertilizer and water[1-3]. According to some researches, nitrogen, as the necessary mineral element of chlorophyll biosynthesis, will have a direct impact on the enzyme content; phosphorus and potassium will stimulate the transfer and transport of photosynthates, thus affecting photosynthesis in an indirect way. Planting mode could improve population structure and soil micro-environment, and shall directly or indirectly affect photosynthesis, and therefore exert impacts on the production. Drip irrigation origins from Israel in the 1960s. In the 1990s, Xinjiang succeeded in the drip irrigation experiment for field cotton[7-9]. In 2011, drip irrigation technology was adopted for peanuts planting in sandy semiarid region in northwest Liaoning province, China. At present, many researchers have already completed a series of studies on drip irrigation planting technology and translocation of water and fertilizer, but they are mostly on cottons and fruit trees. There are few researches on translocation rule and yield-increasing mechanism for peanuts with fertilization under mulched drip irrigation in the local area, especially without intensive studies on photosynthetic physiological characteristics. This article, whose focus is on peanut cultivation in sandy semiarid region under mulched drip irrigation, will prove to be thorough studies about impacts on peanut photosynthesis characteristics and chlorophyll content with the different topdressing under fertilization, while in combination of harvest fluctuation features for further analytic demonstration, all of which shall serve as theoretical reference for more detailed research on drip irrigation for peanut growth and physiological changes impact, most important to the further discovery of peanut yield increase under drip irrigation with fertilization[10-12]. International Conference on Mechatronics, Electronic, Industrial and Control Engineering (MEIC 2015) © 2015. The authors Published by Atlantis Press 977 I. MATERIALS AND METHODS A. General situation of test area The experiment was conducted at Zhanggutai test station of Liaoning Academy of Agricultural Sciences, with the conditions as north latitude 42°42′, east longitude 122°32′, altitude 213.1 m, loam soil for farming, organic matter content of 27.4g/kg, available nitrogen 143 mg/kg, phosphorus 66.0 mg/kg, potassium 108 mg/kg, pH value of 5.6. In this area, frost-free period is 150~155 days, with accumulated temperature (≥ 10°C) as 3468°C, annual average temperature as 6.82°C. The annual average rainfall is 500~520mm, mostly focused in July and August, and the annual average evaporation is 1600~1800mm. Dryness is about 4.0, as that in a semi arid region, where spring drought, summer drought and autumn hanging occurs, or spring drought, summer drought and autumn hanging occurs alternately. B. Research design and methods Cropping patterns as drip irrigation under mulch was adopted for such an experiment, with the detailed description as furrow top width of 65cm, ridge furrow bottom width of 95-100cm, 10cm~12cm high, two rows for furrow planting with row spacing of 35cm, where in the dripping belts were paved, row spacing of 8~10cm for precise sowing of a single seed[13-14] , and the planting density was 14,000 plants per 667m2. The drip fertilization period is the flowering stage (early July) and pod swelling stage (early August) respectively, with irrigation amount as 10m3/667m2 times, drip irrigation fertilizer: urea (N), phosphorus and potassium (PK), Calcium nitrate (Ga) for 5 treatments as specified, of which T5 is as the control without topdressing (see Table 1). Each cell is 25 m long and 4 m wide, three times repeated.. Coated mechanical seeding was conducted in mid May, 2014, with fertilization as organic fertilizer 3000kg/667m2, peanut release fertilizer 50kg/667m2, peanut-specific fertilizer 10kg/667m2, multi-micronutrient fertilizer 1kg / 667m2 before sowing. Tested variety is Fu Hua17. TABLE 1 DIFFERENT FERTILIZER APPLICATION RATES FOR PEANUTS UNDER MULCHED DRIP IRRIGATION The experimental plot number Treatment Fertilizer amount(kg/667m2.times)