Effects of sowing parameters of millet precision seeder on growth characteristics and yield of Jingu 21

Millet (Setaria italic L.) is an important food crop in arid and semi-arid areas in northern China. Jingu 21 has a long planting history and good quality. Effects of different seeding distance and seeding rate of self-propelled millet precision seeder on Jingu 21 emergence quality, photosynthetic characteristics and yield were explored to provide some theoretical bases and technological approaches for mechanized precision seeding of grain in hilly areas in this paper. Taken Shanxi Province as the research area, the tests were carried out in Taigu County and Zezhou County from 2013 to 2014. In Taigu County, Jinzhong City, the row spacing of the precision seeder was 33.3 cm, and the seeding depth was 3 cm in 2013. The emergency tests adopted the split-split plots design, the main plots were two treatments of suppression and non-suppression, the split plots were set to three seeding distance of 7, 10, and 13 cm, and the split-split plots were the three seeding wheels F, X and YJ (the groove diameter of F seeder is 5 mm, the depth is 2.5 mm, round, and the seeding rate is 3-4 seeds per hole; the groove diameter of X seeding wheel is 4 mm, the depth is 2 mm, round, and the seeding rate is 2-3 seeds per hole; the groove diameter of YJ seeding wheels is 5 mm, the depth is 1.8 mm, V-shaped, and the seeding rate is 1-2 seeds per hole). Emergency number and emergency uniformity were measured. The other experiments used a random complete block design without repression. Chlorophyll a content (Chl-a), Chlorophyll b content (Chl-b), Chlorophyll a+b content (Chl-a+b), Carotenoid content (Car), net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), the PSII actual photochemical efficiency (ΦPSII), apparent photosynthetic Electron Transport Rate (ETR), photochemical quenching coefficient (qP), the non-photochemical quenching coefficient (NPQ) in the 2nd leaf from top of Jingu 21 at filling stage, yield and yield components at maturity were measured respectively. In 2014, the yield verification tests in Zezhou County, Jincheng City were carried out, the test treatments were that the seeding rate was 2-3 grains and the seeding distance was 7 cm (X-7), the seeding rate was 2-3 grains and the seeding distance was 10 cm (X-10), the seeding rate was 1-2 grains and the seeding distance was 7 cm (YJ-7), the seeding rate was 3-4 grains and the seeding distance was 13 cm (F-13), the seeding rate was 3-4 grains and the seeding distance was 10 cm (F-10) for. The results in Taigu County showed that for the same seeding distance, the order of emergency number from large to small of different seeding wheels was F seeding wheel, X seeding wheel, YJ seeding wheel, the standard deviation of plant distance was F seeding wheel, X seeding wheel, YJ seeding wheel; for the same seeding wheels, the order of emergency number of different seeding distance from large to small was 7 cm, 10 cm, 13 cm, the order of standard deviation of plant distance was 7 cm, 10 cm, 13 cm. The emergency number with repression was higher, the plant distance and the standard deviation of plant distance was smaller, and the emergency was more uniform. With the increase of seeding rate and the deacrese of seeding distance, carotenoid content showed a downward trend in the 2nd leaf from top of Jingu 21 at filling stage, and Chl-(a+b) increased first and then decreased; Pn and Gs decreased, and Ci increased; ΦPSII, ETR, NPQ and qP has no significant difference; the number of spikes per 667 m2 showed an upward trend, and weight of grains per spike showed a downward trend, and the yield increased first and then decreased. With the decrease of seeding rate and the deacrese of seeding distance, other indicators showed opposite trends. The results of Zezhou County was similar to that of Taigu County. Analysis showed that under the condition of the row spacing with 33.3 cm, seeding rate of precision seeder with 2-3 grains, and the seeding distance with 10 cm (X-10), the yield of Jingu 21 was relatively higher. The theoretical yield of Taigu county was 290.04 kg/667 m2, the actual yield of Zezhou countywas 242 kg/667 m2, and the uniformity of emergency was high, which could achieve the effects of less or no seedling thinning. When the soil moisture is poor, the seeding rate and earth covering and suppression should be increased appropriately, and reducing the seeding distance to ensure the emergency quality.