【Objective】 The effects of source reduction on yield, dry matter, and nutrient accumulation and transport of nitrogen, phosphorus, and potassium under different density populations were discussed in this study, in order to provide more effective ways for further improvement of maize yield and nutrient use efficiency and to provide a reference for the selection and breeding of density-resistant varieties.【Method】 The cultivar Xianyu335 was used for experimental material, which was planted most popularly in local production. A split plot design with three replicates was used in the experiment. The main plot was different densities with 60 000 plants/hm 2 (conventional density) and 90 000 plants/hm 2(high density), respectively; The subplot was different sources reduction intensity by cutting the leaves of each plant by 1/2 (T1), 1/3 (T2), 1/4 (T3) and control (without cutting leaves) at silking stage. Dry matter weight and the contents of nitrogen, phosphorus, and potassium were determined, and dry matter and nutrient accumulation and transport were calculated. 【Result】 Under conventional planting density, the number of kernels per ear, 100-kernel weight, and grain yield were all decreased compared to the control under different levels of source reduction. Among them, the average yield of T1, T2 and T3 were 32.1%, 20.3% and 11.9% lower than that of the control in two years, respectively; Under high planting density, T3 treatment significantly increased the number of kernels per ear, which resulted in a significant increase in yield. The average yield in two years in T3 treatment was 7.7% higher than that of control. Compare with the control, the dry matter and the nutrients of nitrogen, phosphorus and potassium transport rate of vegetative organs were increased at different source reduction, the greater the source reduction, the higher the dry matter and nutrient transport rate. Under conventional planting density, the vegetative organs nutrients of nitrogen, phosphorus and potassium transport rate of T1, T2 and T3 were 25.4%, 19.1%, 10.7%, 14.3%, 9.8%, 5.2% and 19.0%, 10.7%, 8.4% higher than the control, respectively. While, under high planting density, the vegetative organs nutrients of nitrogen, phosphorus and potassium transport rate of T1, T2 and T3 were 17.1%, 12.8%, 5.8%, 12.6%, 8.0%, 3.6% and 14.9%, 11.3%, 3.9% higher than the control, respectively. Under conventional planting density, the differences of source reduction reduced the accumulation of nitrogen, phosphorus and potassium nutrients in grains. While, under high planting density, the accumulation of nitrogen, phosphorus and potassium nutrients in grains were increased at an appropriate source reduction level. The accumulation of nitrogen, phosphorus, and potassium were 11.1%, 6.9%, and 6.1% higher, respectively, than the control on average of two years under T3 treatment. But the nutrients of nitrogen, phosphorus and potassium under T1 and T2 treatments were 20.4%, 23.4%, 20.0% and 10.3%, 15.6%, 16.0% lower than the control, respectively.【Conclusion】 Leaf redundancy existed in dense maize population, reduction the amount of leaf sources appropriately (cutting all the leaves by 1/4 of whole plant) promoted the dry matter, nitrogen, phosphorus and potassium nutrients transport rate from vegetative organs to the grain, and increased the accumulation of nitrogen, phosphorus, and potassium nutrients in grains at mature stage. Therefore, increasing the density reasonably should be adopted in maize production. Meanwhile, the appropriate reduction of leaf source volume under high density population should be an effective way to further increase high yield and efficient use of nutrients in spring maize.
【Objective】 This research aimed to investigate the characteristics of grain yield, nutrient accumulation and transport of spring maize before and after flowering under different agronomic management practices, so as to provide theoretical and technical support for high yield and efficient production of spring maize. 【Method】 The field experiment was conducted from 2009 to 2012 in Gongzhuling of Jilin province. The hybrid “Xianyu335” was used as research material. During three consecutive years, five different agronomic management practices (CK, FP, Opt-1, Opt-2, and Opt-3) were set under the field conditions. The characteristics of dry matter accumulation, nutrient absorbing and transport were monitored before and after flowering of spring maize. The influence of grain yield was studied under different agronomic management practices. 【Result】 Reasonable densification, nutrient management and deep scarification were the key measures for high yield of spring maize. The result indicated Opt-3 was optimal under five different agronomic management practices. Compared with FP, the grain yield and dry matter accumulation of Opt-3 increased 13.9% and 22.4%, respectively. The number of maize ears in harvest stage contributed yield mostly, and the yield under Opt-3 was 34.3% higher than that under FP. Under the condition of same amount of fertilizer input between Opt-3 and FP, N, P and K accumulation of Opt-3 increased by 9.5%, 28.1% and 23.9% than that of FP, respectively. N, P and K translocation rate of Opt-3 increased by 47.7%, 21.7% and 45.0%, respectively. Partial productivity of N, P fertilizer increased by 14.0% and 4.4%, respectively. Compared with Opt-1, the grain yield of Opt-3 was further augmented by increasing planting density. When planting density was increased by 10 000 plant/hm 2, the grain yield increased 56-346 kg·hm -2. Compared with Opt-2, the efficiency of Opt-3 was improved through further optimization of fertilizer, and ANUE of Opt-3 increased 29.5%. Through fertilizer cost accounting, compared with FP, Opt-3 increased income by 2 218 yuan/hm 2. Compared with Opt-1, Opt-3 increased income by 290 yuan/hm 2. Compared with Opt-2, Opt-3 saved 367 yuan/hm 2.【Conclusion】 By reasonable densification to 70 000 plant/hm 2, optimized fertilizer (N 225 kg·hm -2-P2O5 90 kg·hm -2-K2O 90 kg·hm -2) and application period, organic fertilizer (1 500 kg·hm -2), added microelement fertilizer (150 kg·hm -2), combined with soil deep tillage, it was a relatively optimized integrated agronomic management mode, which could realize the synergistic improvement of spring maize yield and efficiency in the middle of northeast China.
【Objective】 Aiming at the accumulation dynamics and translocation and distribution characteristics of dry matter and nutrient of maize population among different cultivation modes under drip irrigation and fertilization conditions in semi-arid region of Northeastern China, this research provided the theoretical basis on high-yielding cultivation technique of spring maize under drip irrigation and fertilization conditions in the area.【Method】 The location experiment was conducted in Qian'an county in the western semi-arid region of Jilin province from 2014 to 2016 with three cultivation modes, including farmers' practice cultivation (FP), high-yielding cultivation (HY) and super high-yielding cultivation (SHY) under drip irrigation and fertilization conditions. Nonghua101 was chosen as experimental material. The characteristics of accumulation, translocation and distribution of dry matter and nutrient of maize population and the yield construction were studied among different cultivation modes under drip irrigation and fertilization conditions. 【Result】 The maize yield under HY and SHY modes were significantly higher than that under FP mode, with the average increment by 16.0% and 37.4%, respectively. The spike kernels and 100-kernels weight of HY and SHY modes were decreased than that of FP mode, but the spike numbers per unit area were significantly increased. Compared with FP mode, dry matter and N, P and K accumulations of maize population were significantly increased under HY and SHY modes from flowering stage to maturing stage, and the accumulation proportion of dry matter and N, P and K accumulations were increased in total growth period after flowering stage (the accumulation proportion of dry matter and N, P and K accumulations in total growth period after flowering stage were increased by 8.0%, 23.3%, 10.0%, 33.9% and 13.8%, 42.6%, 21.6%, 44.6%, respectively). Logistic equation analysis showed that the maximum and average increase rates of HY and SHY modes were 6.9%, 4.2% and 23.8%, 10.9% higher than that under FP mode, respectively, and the occurrence time of maximum rate was later. Compare with FP mode, HY and SHY modes reduced significantly nutrient translocation rate and contribution rate of translocation nutrients to kernels before flowering stage, and improved significantly contribution rate of accumulation nutrients to kernels after flowering stage of spring maize. Correlation analysis showed that the grain yield was significant or extremely significant correlated positively (r=0.7513-0.9840) with the dry matter and N, P and K accumulations around flowering stage of maize population, and the correlation coefficients after flowering stage were higher than them before flowering stage. 【Conclusion】 Compared with FP mode, HY and SHY modes improved the maximum and average increase rates of the dry matter in maize population, and postponed the occurrence time of the maximum increase rate of the dry matter. HY and SHY modes increased the dry matter and nutrient accumulations from flowering stage to maturing stage of maize, and enhanced significantly the contribution rate of accumulation nutrients to kernels after flowering stage. Therefore, the managing measures of increasing the planting density, controlling the total amount of N, P and K fertilizers and regulating fertilizer application during different stages could ensure the demand of N, P and K in the whole growth period of maize. This article provided an advantageous way for further promoting maize yield under drip irrigation and fertilization conditions in the semi-arid region of Northeastern China.
【Objective】 In order to improve phosphorus efficiency and reduce environmental risk due to a large number of phosphorus application under mulched drip irrigation in northeast semi-arid region for maize production, a 3-year field experiment was conducted to investigate the effects of different phosphorus application rates on maize yield, phosphorus utilization efficiency and soil phosphorus supply ability, so as to provide scientific references for rational phosphorus fertilizer application in this region. 【Method】 The field experiment was conducted in semi-arid maize production region of Jilin province (Qian'an county) from 2015 to 2017. Six treatments of phosphorus application rate (P2O) were designed in the field experiments, including 0 (P0), 40 kg·hm -2 (P40), 70 kg·hm -2 (P70), 100 kg·hm -2 (P100), 130 kg·hm -2 (P130) and 160 kg·hm -2 (P160), which were used for the calculation of phosphorus uptake, phosphorus utilization efficiencies and apparent phosphorus balance in the soil-crop system. The measurement indexes contained maize yield and its components, phosphorus content of plant at mature stage and soil available phosphorus concentration. 【Result】 The result showed that the maize yield with phosphorus application were significantly increased by 6.2%-21.2% (2015), 9.0%-20.6% (2016) and 12.9%-30.3% (2017) respectively, and increment by 9.2%-23.9% in average three years. The yield was enhanced by increasing grains per ear, 100-kernel weight and harvest index by applying phosphorus fertilizer. Maize yield increased at first and decreased later with increasing of phosphorus application rate, and the highest yield value was found under P100 treatment. Phosphorus recovery efficiency and partial productivity declined, however, phosphorus agronomic efficiency increased at first and decreased later with increasing of phosphorus application rate. Available phosphorus content in soil layer (0-40 cm) was improved with the increasing of phosphorus application rate and period compared with P0 treatment, and the content under P100 treatment was very close to its initialization value. The apparent phosphorus balance in soil was negative in the P0, P40 and P70 treatments after a three-year continuous maize-cropping, and the phosphorus deficient amount was decreased with the increment of phosphorus application rate. While the apparent phosphorus balance in soil was positive under the P100, P130 and P160 treatments, and phosphorus surplus amount was increasing with the increment of phosphorus application rate. When surplus rate was 0, phosphorus application rate, maize yield, available phosphorus content in 0-20 cm and 20-40 cm soil, phosphorus recovery efficiency, agronomic efficiency and partial productivity were 92.4 kg·hm -2, 12 497 kg·hm -2, 34.6 mg·kg -1, 28.4 mg·kg -1, 24.1%, 21.9 kg·kg -1 and 146.1 kg·kg -1, respectively, by simulating between phosphorus application rate (y1), soil available phosphorus content (y2), phosphorus utilization efficiency (y3) and surplus rate (x), respectively. These results were similar to maize yield, soil available phosphorus content and phosphorus utilization efficiency under the maximum yield under the P100 treatment. The optimum phosphorus application rate was at the range of 88-97 kg·hm -2 under 95% confidence levels, when theoretical surplus rate was 0. 【Conclusion】 The results suggested that the recommended phosphorus application rate was at the range of 88-97 kg·hm -2, which could not only ensure higher maize yield, but also keep soil phosphorus balance under this experimental conditions. The research provided phosphorus fertilizer management for both high-yielding maize production and friendly environment under mulched drip irrigation conditions in northeast semi-arid region of Jilin province.
