Matters needing attention in Regional Test of Cotton varieties (Lines)

The regional comparison test of cotton varieties (lines) is to compare the newly introduced local varieties (lines) with the main local varieties to identify their characteristics of early maturity (growth period), high quality, high yield and resistance to diseases and insect pests, as well as economic characters and fiber quality. The main purpose of this paper is to identify the performance of the tested varieties (lines) in each cotton area, so as to provide a scientific basis for the selection of excellent varieties in each cotton area.

I. selection of experimental sites

The selected experimental site should be representative and consistent. It is required that the land is flat, the fertility is medium and uniform, the previous crop is consistent, the irrigation and drainage is convenient, the location of the experimental plot is appropriate, the light is sufficient, and it is not affected by microclimate factors.

II. Design requirements of residential area

The field planting map and the arrangement diagram of the tested varieties in the experimental plot were drawn before sowing in the experimental site. Under plastic film cultivation, the tested varieties were randomly arranged and repeated 4 times. The net area of each district is 20 square meters, there is no walkway between the same repeated plots, there are protective rows at the side of each repetition, and the walkways are 50 cm wide and 100 cm wide between repeats, and the rows are planted in wide and narrow rows, and the row spacing is determined according to the local field cultivation model and experimental requirements. 2-3 cotton seeds were sown artificially in each hole.

III. Test methods and requirements

The field observation of the experiment must be carried out by a special person and kept stable, and the records must be timely and accurate to ensure that comprehensive and reliable data are obtained. The record book should be in duplicate, the original should be used in the field, and the copy should be kept indoors. Records should be sorted out in time. The records of the investigation project shall be carried out in accordance with the uniformly prescribed methods and standards, and shall be filled in with a unified form.

After the seedling was fixed, in the middle section of the middle two rows of each plot, 10 disease-free plants with normal growth were selected as special plants for growth and character observation in each plot.

The investigation records of the characters in the growing period are mainly as follows: five major growth periods; seedling protection plant number, seedling preservation rate, headless plant rate, dead seedling rate, growth potential, uniformity, cold tolerance, seedling diseases and insect pests at seedling stage; observation of growth potential, uniformity and agronomic characters, leaf color and plant type before topping at flower and boll stage Growth potential, uniformity, first fruit branch position and initial node height, fruit branch number per plant, effective boll number, fruit node number, boll setting rate, boll number before frost, etc.

IV. Requirements for recording agricultural operations

Recording the date, quantity and method of each agricultural operation is helpful to correctly analyze the test results.

The treatment of the experimental land must be timely to ensure that the moisture content is sufficient and the land is flat. After the seeder has laid the film, the plot should be divided in time to avoid the delay of manual on-demand. Manual on-demand must be completed in the same day, with appropriate depth (3-4 cm) and 2-3 seeds per hole. The soil cover is not easy to be too thick, so it should be covered with broken and wet fine soil, and then pressed manually to ensure that the soil moisture is good and the seedlings emerge neatly and consistently.

The agricultural operation activities and the response of varieties to adverse environment should be recorded in a series of experiments, such as soil properties and pre-cropping stubble, cultivated land and soil preparation, inter-seedling, fixed seedling date, weeding, fertilization (including foliar fertilizer), irrigation, chemical regulation, topping and pruning, disease and pest control and so on.

V. Major climatic observations and records

Any change in environmental conditions will cause corresponding changes in crops, which will finally be reflected by the yield. Due to the lack of climate records, it is often impossible to clarify the reasons for the high and low yields of some varieties. The variety comparison test requires recording the average air temperature from March to October, the maximum and minimum temperature of each month, the active accumulated temperature of ≥ 10 ℃, the date of the first and last frost, the days of frost-free period, the total precipitation from March to October, and the main weather changes.

VI. Flower harvesting and indoor seed testing requirements

In order to make the observation records and measurements really help to draw a more comprehensive and correct conclusion about the experiment, the technicians must do it carefully and accurately. First of all, the samples observed must be representative. Secondly, the recorded and measured items must have unified standards and methods, and each observation item of the test must be judged and recorded by the same person to ensure the accuracy of the test. In the middle 2 rows of each plot, 30 normal boll-opening and complete cotton flowers were randomly selected from the first fruit node of the 3rd-5th fruit branches. Indoor seed testing items include single boll weight, cashmere length, cashmere length uniformity, lint percentage, lint index, seed index and infertile seeds.

VII. Yield analysis

Harvest should be timely, meticulous and accurate. The picking time should be flexibly determined according to the morning and evening of each district and the amount of boll opening. When picking, each community should finish it on the same day. All the four communities plan production, pre-frost flower and post-frost flower respectively, peach blossom does not plan production.

The output of seed cotton and lint cotton before frost, the total yield of seed cotton, lint cotton and seed cotton after frost, and the total yield of lint cotton after frost should be counted respectively, and then converted into per unit yield of 667 square meters, flowers before frost, and picked again with 2 days after frosting as the boundary. Lint yield in plot = seed cotton yield in plot × lint percentage of flowers tested in plot. After harvest, the number of harvested plants in each community should be investigated, then converted into the number of harvested plants per 667 square meters, and finally the missing plant rate should be calculated according to the theoretical number of 667 square meters.

In the plot yield analysis, the lint yield before frost was analyzed by variable analysis, and then the significant difference of each variety was determined by the new compound difference method.