Flowering Prediction and Regulation of Maize Hybrid Seed Production
In the process of corn hybrid seed production, flowering encounters are the key to ensuring high yield and seed quality. Whether the father and the mother are met at the flowering stage, in addition to being affected by human factors, the influence of natural factors in the growth and development of the parents and the changes in the geographical environment caused by the external parents may lead to the flowering period. The author summarizes the practical experience of corn hybrid seed production that flowering stage prediction and flowering regulation are particularly important for corn hybrid seed production.
First, the method of flowering prediction
In order to make the father's loose powder period meet the maternal silking period, it is necessary to determine the sowing date according to the parental birth period, especially the length of time from emergence to loose powder and silking. The determination of the sowing date adheres to the principle of “taking the father as the main and regulating the motherâ€. It is better to use the maternal silk to be 1-3 days earlier than the father. There is a difference between the sowing date and the emergence of the seedlings according to the soil condition, and the ratio of the difference between the emergence period and the flowering period is 2:1, that is, the emergence period is 4 days, and the flowering period is only 2 days.
In production, although the sowing date is coordinated and the sowing is carried out in a wrong period, it may be affected by conditions such as climate and soil during emergence, growth and development, and it is inevitable that the flowering period will not meet. To this end, it is necessary to timely forecast the flowering period in order to take timely adjustment measures. At present, there are two methods for flowering prediction:
1. The leafless calculation method predicts the flowering period by counting the number of leaves of the parents. In the seeding field, the same combination selects 4-5 of the representative surveys of the parental and maternal births, and marks the 5th, 10th, and 15th leaves in the growth of the plants. In general, the combination of the number of leaves of the parent and the female parent, the number of leaves before the flowering is less than the number of leaves of the male parent is 1.5-2 leaves, which is a good sign of the flowering period. Parents have the same number of leaves in the same group. Before flowering, the undeveloped leaves of the parents are more than 1-2 leaves more than the female parent. At this time, a leaf is usually grown about 3 days, that is, the male parent is 5-6 days later than the female parent. time. The maternal from the tasseling to the loose powder to the silking of the ear, generally 5-6 days, the vitality of the filament is 7-8 days, the pollination ability is the strongest after 3-6 days of silking, and the seed setting rate is the highest. The father's pollen is usually finished in 5 days, and the powder is 3-4 days after the loose powder. This happens to coincide with the parents' flowering period. Otherwise, the flowering period will be poor, and it is necessary to take timely measures to adjust.
2, tassel size comparison method After corn jointing (13-17 leaves), tassels have begun to differentiate. By comparing the differentiation process of both parents' tassels, the flowering period can be accurately predicted. The specific method is to select three representative plants (one male and one female) in the breeding field. After unplugging, the leaves are peeled off from the outside to the leaves. When peeling leaves, they should be particularly careful. Spikes, measuring the length of the tassels, for comparison. The tassels before tasseling are generally divided into three periods, namely, the early, middle and late stages of the tassel. If each period is consistent with the length of the parental tassel of the table below, it indicates that the flowering period meets well. If the size of the tassel is not within this range, it will cause the flowering period to be met, and it should be adjusted in time.
Observed period
(length cm) (length cm)
Early stage (joint period) 1-20-0.5
Medium term (small bell mouth to big bell mouth) 3-61-3
Late stage (before the exit) 7-148-7
Second, flowering regulation and remedial measures
According to the various periods of the flowering period forecast, the corresponding corresponding adjustment measures are taken to ensure that the flowering period meets. The specific method is as follows.
1. It is advisable to regulate the seedling stage in the seedling stage. If the seedling stage is found to be dysfunctional, the parents who are late in growth should be partial to fertilizer and partial water management, increase the number of shovel, increase the ground temperature, promote the growth and development of the seedlings, and grow too fast. The parents should take appropriate night seedlings and seedlings to inhibit their growth.
2. After the jointing and booting stage control enters the jointing stage, the parents with slow growth and development are given more fertilizer and water management, and the external fertilization and plant growth regulators are used together. The specific method is: use 20-30 mg / kg of gibberellin and 1% urea mixture, spray in the big bell mouth period, 667 square meters spray 80-100 kg liquid medicine, spray 1 time can adjust the flowering period 3-4 day. You can also use 20-30 mg / kg of gibberellin and stimulation spray, or use 1% - 2% potassium dihydrogen phosphate plus 1% - 2% urea mixture spray, spray every 7 days or so The number of sprays is determined according to the need, and 667 square meters is sprayed 15-25 kg. However, it should be emphasized that the use of gibberellin can not exceed 3 times, otherwise the pollen will lose its vitality and lose its regulatory significance. Spraying with naphthalene acetic acid aqueous solution at the booting stage, the effect is also very good, the tassel flowering period can be advanced 3-4 days, does not affect the tassel loose powder, the spray volume is 667 square meters 80-100 kg.
In the corn big bell period to 3 days before the tasseling, the external top dressing and plant growth agent are regulated, which can improve the uniformity of the male broth and shorten the male tasseling period, thereby reducing the number of artificial emasculation, saving labor and improving seed production. quality.
In addition, for the parents who develop faster, the root system is cut by deep cultivating, and the cutting length is determined according to the length of the difference between the loose powder and the silking of the parent, and the difference is long and the root is broken, and the root is broken. After the root is broken, the growth center of the plant is destroyed, so that most of the nutrients are transported downwards, and the growth of the aboveground part is controlled, so that the faster-developing parent is delayed for silking or squirting for about 4 days.
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