Study on the efficiency of Cotton Light Table in different planting patterns

In order to further increase the cotton yield, it is difficult to increase the number of plants per unit area. In production, it is necessary to increase the density, improve the poor ventilation and light transmittance in the middle and lower part of the cotton population, and improve the light transmittance and photosynthetic efficiency in the middle and lower part of the cotton population. In this paper, through the study of cotton population photosynthetic efficiency and light transmittance of different planting patterns, in order to determine the reasonable cotton population structure in specific areas, and to provide a basis for high-yield and high-quality cotton cultivation.

I. Materials and methods

1. General situation of test

The experiment was carried out in the Agricultural Experimental Station of Shihezi University from 2002 to 2003. The fertility of the experimental land is medium, the previous crop cotton, the tested cotton variety is Zhongmiansuo 36, and the sowing date is April 29.

two。 Test setup

Cotton planting density: 10000 plants / 667m2, 15000 plants / 667m2, 20000 plants / 667m2. The row spacing is 60cm wide and narrow.

Topping treatment: each density was divided into three treatments: 1 topping (July 10), 2 topping (July 10, 25) and 3 topping (June 25, July 10, 25) (the following topping methods were all expressed by 1 time, 2 times and 3 times). Random block arrangement, 3 repeats. The area of the community is 30 square meters, 5 meters wide from north to south and 6 meters from east to west. Plastic film mulching cultivation adopts the planting method of covering plastic film first and then sowing on demand. During the growth period, there are no weeds in the field, and other management is the same as in the field.

Topping order: one topping treatment means that all cotton plants are knocked off the top at once on July 10. The two-time topping treatment refers to the top of the two rows of cotton plants in the middle on July 10 and the tops on both sides on July 25. Three times topping treatment means that the tops of any one row of cotton plants in the middle two rows were knocked out on June 25, the tops of cotton plants in the other row in the middle row on July 10, and the tops of cotton plants on both sides on July 25.

3. Test project

The photosynthetic rate of cotton was measured by infrared carbon dioxide analyzer at the initial flowering stage, full boll stage and boll opening stage, and three representative samples were selected for each treatment. Cotton population photosynthetic rate was measured at 12:00 in the morning on a sunny day.

The light transmittance was measured by illuminance meter during the full boll stage of cotton, 80 × 90 cm representative sample points were selected for each treatment, and 9 treatments were measured at 12:00 in the morning on a sunny day. Each sample point was measured by vertical bar cable (one level per 10 cm), and 17 points in each level were measured from bottom to top and from outside to in. the data were processed by computer.

II. Results and analysis

1. Changes of photosynthetic rate in different planting patterns at different growth stages

The population photosynthetic rate of cotton with different planting patterns was the highest in the early flowering stage with the density of 20,000 plants / 667 square meters. In addition, compared with the other two topping methods under the same density, the population photosynthetic rate of two topping treatments with a density of 20,000 plants / 667 square meters was the highest, followed by the population photosynthetic rate of one topping treatment, and the third was the population photosynthetic rate of three topping treatments. This is mainly due to the unreasonable distribution of cotton population leaves formed by one topping and three topping, resulting in the difference of cotton population photosynthetic rate. It can be seen that the population photosynthetic rate of 20,000 plants / 667 square meters in the early flowering stage is the highest.

The population photosynthetic rate of cotton with different planting patterns was higher than that of the other two topping methods at the full boll stage, and the population photosynthetic rate of the two topping methods with the density of 10,000 plants / 667 square meters was significantly higher than that of the other two topping methods under the same density. On the whole, the method of topping twice at the density of 20,000 plants / 667 square meters at full boll stage was more reasonable, and the population photosynthetic rate reached an ideal state.

During the boll opening stage, the population photosynthetic rate of cotton with different planting patterns was significantly higher than that of the other two topping methods at the same density.

At the initial flowering stage, full boll stage and boll opening stage, the cumulative photosynthetic rate of cotton with the density of 20,000 plants / 667 square meters was the highest, and the lowest density was 10,000 plants / 667 square meters. This is mainly because the competition among 10, 000 plants / 667 square meters is relatively small, among which the middle row topped on June 25 is short, the edge disadvantage reaches a large value, and the photosynthetic efficiency is very low. As a result, the population photosynthetic rate decreased.

two。 Effects of different planting patterns on light transmittance of population

The canopy light transmittance of cotton in different planting patterns showed that the canopy light transmittance decreased with the decrease of canopy height, and the light transmittance of cotton plants above 40 cm decreased relatively slowly. Among the three densities, the light transmittance of the canopy varies greatly from 40 cm to 70 cm, the light transmittance is concentrated, and the canopy transmittance changes slowly below 40 cm. In particular, the change of cotton population transmittance is more consistent with this law, especially under the density of 20,000 plants / 667 square meters, which shows that the canopy transmittance of cotton under the density of 20,000 plants / 667 square meters is more reasonable.

3. Effects of different planting patterns on lint yield

The cotton yield determines the utilization of light energy by the cotton plant population. A reasonable group can not only give full play to the best productivity of the individual, but also give full play to the potential of increasing production. The density had a significant effect on the number of fruit branches and boll weight per plant, while the different topping methods changed the cotton canopy and affected the light transmittance of cotton plants. the comprehensive effect of the two treatments directly affected the final yield of cotton.

Through the determination of cotton yield under the same density and different topping methods and the lint yield of cotton plots with different planting patterns, the results showed that the lint yield of cotton with different topping methods under three densities was the highest with a density of 20 000 plants / 667m2, which was 136.732 kg / 667m2. In addition, the yield increased obviously with the increase of density from 10,000 plants / 667 square meters to 20,000 plants / 667 square meters. The results showed that through the treatment of different planting methods, the population structure of Zhongmiansuo 36 was reasonable at the density of 20,000 plants / 667 square meters.

III. Summary

1. The photosynthetic rate of cotton population with different planting patterns was the highest when the density of 20000 plants / 667 square meters was topped twice at the initial flowering stage, full boll stage and boll opening stage. it can be seen that the cotton population with the density of 20,000 plants / 667 square meters has greater photosynthetic potential.

two。 The light transmittance of cotton in different planting patterns decreased with the decrease of plant height. under the density of 20,000 plants / 667 square meters, the light transmittance was concentrated in the canopy of 40 cm to 70 cm, and changed gently below 40 cm. In production, concentrate fruit branches above 40 cm as far as possible.

3. The lint yield of cotton with different planting patterns was the highest under the density of 20,000 plants / 667 square meters.