| Broomcorn millet is the main food crops and cash crops on dryland in north China. Millet Growth and yield strength level in addition affected by species genes, the cultural practices sowing and density are also the important factors influencing yields,suitable sowing could to ensure full use the local light, temperature, water, gas and other natural resources, reasonable groups to coordinate the conflict between the individual and the population in growth process of Millet, thus by the regulation of sowing date and density in produced in some extent is the important way to achieve high yield and quality of Millet.Yu Mi 2 as the study materials, split plot design, set five sowing date, four planting density to study the influence to broomcorn millet plant agronomic traits, yield, dry matter accumulation and translocation, photosynthetic characteristics and canopy structure. The main conclusions of the study are as follows:1. Sowing date and density impact the agronomic characters and yield of millet,effective tiller number was greatly decreased with the sowing date postponed, with the increase of planting density decreased. the influencing degree of sowing date is greater than the density on strains high, with the delay of sowing date, plant high overall was first increased and then decreased; stem diameter first increased and then slightly decreased with the sowing date delayed, decreased with increasing density showed M1>M2>M3>M4. Single plant panicle weight, grain weight and single-ear particle weight, grain weight were with the increase of planting density decreased, 1000 grain weight increased first and then decreased with delayed sowing date, decrease with the increase of the density, B3M3 1000 grain weight reached the highest 4.99 g, grain yield is the largest 4194.1kg/hm2 under effect of sowing date and density interaction.Studies have shown that millet’s suitable planting date is mid-June, suitable density is50000/667m2 in northern Shaanxi, increase the sowing density on late sowing, reduce the density on early sowing to effectively coordinate the growth of plants and groups of individuals in order to achieve productive.2. From heading to maturity of millet, the single plant dry matter accumulation increased, the growth rate slowed in later stage, showed "S" curve. M1 have the highest dry matter accumulation of individual plant, and gradually decreased with the increase of the density. The amount of dry matter accumulation in B5 was far lower than that in other sowing dates. From heading to maturity, the leaves on the main stem, leaf sheath and stem dry matter accumulation with extension of the growth period increased first and then decreased, at heading after 14 d reached the maximum value. The dry matter accumulation decreased with the increase of the density of leaf, leaf sheath and stem, changes had no obvious regularity with different sowing date. The accumulation of dry matter in the top leaves decreased with the increase of the density, and the effect of sowing time was small. The dry matter of flag leaf decreased at heading after 28 d, the date was later than that of the second top leaf and third top leaf. From heading to maturity, the dry matter accumulation of B1, B2 and B5 had significant difference.Research has shown that grain yield formation process of broomcorn millet is the process plant dry matter accumulation and distribution, in a certain period of time, the more dry matter allocated to reproductive organs the higher yield. Millet stalk, leaf, leaf sheaths is source of assimilates to grain ", when these" source "of the dry matter accumulation reached maximum value, accumulate in different periods will transfer to sink organs-- grain. The leaf dry matter translocation was gradually decreased with the delay of sowing date. B3M3 moving rate is the highest.3. The chlorophyll content of flag leaf millet in heading to maturity period in different sowing first increased then decreased. With the growth process advance,B1 the chlorophyll content in flag leaf rapid increase in the early, at heading after 21 d reaching the peak and then slowly decline. The chlorophyll content of different density was M1>M2>M3>M4 after heading 21 d. The change of B5 flag leaf chlorophyll content at the overall heading is not obvious. Top three leaf chlorophyll content showed a single peak curve, after heading 14 d reaching a maximum value, the second leaf > third leaf> flag leaf. Under different sowing period, the green leaf area of flag leaves, third leaf showed increased first and then decreased, and B1, B2, B3, B5 are peaked at 14 days after heading, B4 peaked in heading after 21 days. Leaf area index showed a unimodal curve first increased and then decreased in the heading stage to mature stage, and increased with increase of the density.Studies have shown that broomcorn millet stem top leaf functional period maintain longer, the chlorophyll content higher, green leaf area was greater, more dry matter transfer to grain, more conducive to the grain formation and grain filling. Therefore, should through regulate sowing date and density, and proper fertilization to maintain the functional period ofleaves, in order to improve the grain yield of millet in production.4. The same sowing period under different density, canopy temperature was M4>M3>M2>M1. Transmittance increases with the growth of millet population gradually.Millet population light transmission rate decreased with the increase of the density, increased with the delay of sowing date. Millet canopy photosynthetic active radiation interception performance for the middle filling stage> late filling stage>early filling stage. B1 in the near infrared range 750-1350 nm and 1450-1800 nm, the millet spectra response under different planting densities performance M4>M1>M2>M3. B3 group spectrum is reflected as the density is bigger, the reflectivity is higher, the density is too high, and the reflectivity is reduced.Comprehensive analysis shows that, broomcorn millet production should according to the local climate conditions to determine the suitable sowing time and according to the variety characteristics to determine the appropriate density, both to ensure that broomcorn millet individual healthy growth and form a reasonable population structure, make full use of when the light, heat, water and other natural resources to achieve high yield and good quality. |
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