Effects of Different Row Spacing and Planting Density on the Main Agronomic Characters and Yield of a Maize Variety Xianyu 335

A field test was conducted to investigate the effects of different row spac- ing and planting density on grain filling rate, yield and other agronomic characters of a maize variety Xianyu 335, thereby determining the optimum planting density for maize in the Huang-Huai-Hai region. The results showed that the grain filling rate of Xianyu 335 was tended to decrease with the increase of planting density, and un- der the same planting density, the grain fill row spacing. Under the planting density of spacing showed little effect on the kernels ng rate decreased with the increased 60 000 plants/hm2, changing the row per spike of Xianyu 335; under the planting density of 75 000 plants/hm2, with the increase of row spacing, the kernels per spike of Xianyu 335 decreased; and under the condition of same row spacing, the yield of Xianyu 335 under the planting density of 75 000 plants/hm2 was higher than that under the planting density of 60 000 plants/hm2. The yield of Xianyu 335 reached the highest level at the row spacing of 50 cm and （40 ＋ 80） cm.

Design and experiment of a Chinese chive harvester

Recognizing the labor intensity of current domestic Chinese chive harvesting and the need for its mechanized harvesting,a self-propelled electric Chinese chive harvester is designed.The machine is composed of a control system,supporting mechanism,cutting parts,conveying and clamping mechanisms,frame,and collection system.It can complete Chinese chive feeding,cutting,transmission,and binning operations at one time.It has a cutting width of 0.25 m and wheelbases of 260 mm and 460 mm.Two 12 V,42 Ah lead-acid batteries were used in series as the power supply.The mechanical properties of Chinese chive were analyzed,and shear and compression tests were carried out to determine that the average value of the maximum shear force on the chives is 129 N.Up to a compressive force of 225 N,Chinese chives are not damaged.According to the physical characteristics of Chinese chives and the requirements of the harvesting operations,design and calculation of the key components of the harvester’s transmission mechanism and the strength of the whole machine frame were completed.An embedded control system and Cortex-M3 microprocessor were used to control the harvester and realize its functions of rolling and harvesting while regulating its speed and protecting its motor.Using the Box-Behnken test design method,the machine’s operating speed,cutter speed,and cutter height were selected as influencing factors,and the lodging rate and loss rate were evaluated as a test.A mathematical regression model of influencing factors and evaluation indexes was established to analyze the influence of these factors and indexes and optimize test parameters.The optimal parameter combination is determined to be:operating speed,1.1 km/h;cutter speed,220 r/min;cutter height 2.0 cm.The parameters were verified from field tests and the results showed that under the optimized parameter combination,the average lodging rate was 3.96% and the average loss rate was 3.23%,indicating that the Chinese chive harvester meets the agronomic requirements of Chinese chive harvesting.This harvester could be modified to harvest other crops such as chrysanthemums and Mongolian Chinese chive.