Section 1 Image of spikelet differentiation

Time flies, and in the blink of an eye, seed rice has entered the booting stage.

The key to hybrid rice seed production is to achieve the flowering period of the parents, only the full flowering period of the parents is completely met, and then the weather is fine, then the seed production will achieve high yield.

In fact, it is impossible to achieve a complete flowering encounter in the production of hybrid rice. Among them, there are many factors that affect the growth and development of rice.

In terms of paternal rice, the two varieties of international 24 and international 661 are determined by their own growth habits, their tillering is relatively concentrated, and neat, and the main stem heading and flowering period is almost synchronous, so the full flowering period is very short, just three or four days.

The growth characteristics of the female Zhenshan 97 sterile line are completely opposite to the characteristics of the male rice, the tillering stage is very long, extremely uneven, the heading is also sparse and pulled, and the full flowering period is not obvious. In order to lengthen the time of the flowering period to meet and overlap, people will divide the paternal parent into three batches of planting, each batch interval of about five days, so that the heading and flowering are three or five days apart, the first period of the male parent is about to end in full flowering, the second period is connected, the second period is about to end, the third period is on top, the full flowering period can overlap up to about two weeks, so as to ensure that the female parent has a sufficient amount of male pollen supply during the heading and flowering.

Theoretically, this is the case, and the seed production in the field is also carried out under the guidance of this theory.

In practical application, the growth and development process will be affected to varying degrees due to factors such as climate, soil, fertilizer, irrigation, diseases and pests. Therefore, once the seedlings enter the spike differentiation stage, it is necessary to observe the progress of the spikelet differentiation and judge whether the flowering period meets.

The so-called practice is the only criterion for testing theories.

The whole growth period of rice is long and short, the long is more than 140 days, and the short is less than 100 days, but no matter what variety, no matter what region it grows in, or altitude, latitude, the time of young panicle differentiation is roughly the same, that is, from the beginning of young panicle differentiation to heading and flowering, it is basically about 30 days. In addition, although rice is relatively stable in the stage of panicle differentiation and development, it is particularly sensitive to microclimates such as external environment such as water, fertilizer, and temperature, and its development progress can be artificially adjusted by using this growth characteristic.

The methods of regulating the flowering period include irrigation, fertilization, and spraying 920 growth hormone. All these measures can promote its development and speed up heading. On the contrary, if the water in the paddy field is drained and the root system is shelved, the root system is cut off, and the root system is broken, the heading progress can be delayed.

When flowering, tap the rice plant with a bamboo pole or pull and scrape it from the rice ear with a long plastic rope to increase its elastic shaking amplitude, which can make the pollen fully flutter and spread more widely, farther and more evenly.

The head of the female parent has the habit of not being able to completely extract the bract of the arrow leaf, that is, one-third of the rice ear cannot be pulled out normally, and this part cannot receive the pollen of the male parent and cannot bear fruit. Take measures such as tapping the bamboo pole, or cutting off the upper leaves, spraying 920, and manually peeling off the bract leaves, etc., which can expose the part originally wrapped in the stem, thereby increasing its pollination surface and improving the seed setting rate. But all of this is based on the premise that the flowering period meets, and the area is large.

In order to predict the flowering period, accurately observe the development progress of rice panicles, and improve the prediction accuracy, according to the biological characteristics, rice breeding research institutions have summarized the standards of appearance characteristics, which is convenient for people to directly judge the progress of young panicle development from the appearance.

Specifically, the differentiation time of the young spike is vividly divided into eight periods.

The first issue is invisible. When the differentiation of young rice panicles begins, if the main stem of the rice is peeled off, the young panicles at the top of the growth point are invisible to the naked eye, and if they are observed under a microscope, they are slightly raised like nipples. The time experienced during this period is about three days.

The second spike is convex. Under the microscope, the milk-peak of the young spike is more obvious, and the crystal bulge can also be seen with the naked eye, and the experience time is about three days.

Phase 3 plush. The naked eye can clearly see that the young spike is fluffy, like a white pen tip, and under the microscope, the observation is even clearer, and the experience time is about four days.

Four phases of one centimeter. Peeling off the main stem, the young panicle of rice is about one centimeter long, and it can be seen more clearly, and the experience time is about four days.

The fifth phase is one inch long. At this time, the spikes have grown to about an inch long, and the experience time is about three days.

The six grains are present. The shell of the young spike can be seen clearly with the naked eye, and the experience time is about four or five days.

Seven spike buds. At this time, the ears of grain, like a woman who was pregnant in October, had a large belly and a round waist, and were very plump, and the experience lasted about four days.

Eight spikes will come out. Pregnant in October, once delivered, the ears of grain have swelled and opened their leaf sheaths, and they are about to be tasseled and flowered.

Obviously, the most difficult stage to predict is the first and second stages of spike differentiation, and the development of young spikes in these five to seven days is invisible to the naked eye. If examined with a microscope, there is no such condition here. Therefore, the prediction of these two periods is the most critical, the growth period is nearly a week, if you find that the flowering period is not met, you can take measures to adjust it as soon as possible.

In the practice of seed production, the earlier the measures are taken to adjust the flowering period, the greater the room for maneuver and the better the effect. During this period, it is often predicted empirically or estimated using the sowing date.

The third and fourth phases are the most critical, they can be seen directly with the naked eye, and the judgment is not easy to make mistakes, which is convenient for prescribing the right medicine.

Flowering prediction and flowering adjustment are the core technologies of hybrid rice seed production, and they are also the ability to take care of the family. Only when you really grasp it, can you grasp the initiative to adjust the flowering period. Otherwise, the flowering period will not meet, no matter how well the seedlings grow, they will not be able to produce hybrid rice seeds, and all the efforts can only be wasted.