Wu Jun, Zhang et al. of Haibin No.2 Middle School in Baoshan District, Shanghai.

With the improvement of people's living standards, people's demand for flowers is increasing. The flowers are colorful and fragrant, but they all have the defect of short flowering period. Many reagents, such as aspirin, are used to prolong the fresh-keeping period of flowers. We tried to extend the flowering period of plants with rare earths.

Rare earth is a rare element. Agricultural rare earths are mainly compounds of lanthanum and cerium. It can promote the growth of plants to a certain extent. In order to know whether it affects the flowering period and the size of flowers, we did the following experiments.

I. Experimental materials

Nongle powder (a rare earth fertilizer), calendula, beaker.

2. Experimental process and records: Nongle was prepared into five solutions with different concentrations, inserted into calendula, and a control group was established. The list is as follows: the flower diameter is 3-4 cm.

Nongle solution

Situation record

contrast

50 mg/100 ml

1 Flowers bloom and fall in a few weeks.

Thank you in six days.

100 mg/100 ml

The flowers just opened and died two weeks later, and the flowers were in full bloom.

Slightly larger than the control group.

Thank you in six days.

150mg/100ml

Flowers are in full bloom, wither more than 1 week, and the leaf color is good.

Six days after flowering, the leaves on the branches are worse than before.

200mg/100ml

Flowers are in full bloom, wither more than 1 week, and the leaf color is good.

Six days after flowering, the leaves on the branches are worse than before.

300 mg/100 ml

Flowers are in full bloom, wither more than 1 week, and the leaf color is good.

Six days after flowering, the leaves on the branches are worse than before.

Three. Analysis and discussion

From the above experimental records, it can be considered that rare earth can prolong the opening time of flowers to a certain extent. From 50mg/ 100ml rare earth solution to 3 oomg/ 100 ml rare earth solution, the flowering period can be prolonged and the diameter of the flower is slightly increased. The application of rare earth to marigold can generally prolong the flowering period by 2-4 days. We think this is related to the fact that rare earth can promote plant life activities, promote chlorophyll formation and increase organic matter synthesis (the leaves of plants containing rare earth solution are darker in color). Rare earth can promote the absorption of organic nutrients by plant reproductive organs. We also found that the higher the concentration of rare earth (below 300 mg/l00 ml), the longer the flowering time of the extended flower. As for how high the concentration will be, it needs further study in the future.

Rare earth is a compound containing trace elements, which can promote plant growth to a certain extent. Two students, Zhang and Wu, used agricultural rare earth-Nongle as an experiment to prolong the flowering period of flowers, which is of great practical value. Judging from the article, these two students have really done a lot of work and achieved gratifying results, which is commendable.

Of course, like most students who have independently conducted scientific experiments for the first time, they are not mature enough in experimental methods and report expression. But it doesn't matter. In the future, they will do better by carrying out more such activities and reading more extracurricular books. Compared with many of their peers, they are already one step ahead.

First of all, judging from the contents of the report, the author only conducted experiments on the flowering period of marigold, so the title of the report seems to be changed to "the influence of rare earths on the flowering period of marigold". You know, plant is a concept with great extension, and it can't be used indiscriminately in scientific research reports. If rare earth has an effect on one plant, it is unacceptable to assume that it has the same effect on all plants. This is the so-called generalization, which often leads to a big mistake.

Secondly, the concentration of extremely dilute solution should be expressed in ppm (one millionth), such as "50m g/ 100ml" in this paper can be expressed as 500ppm.

Third, the number of experiments with marigold should be clearly recorded in the report (at least 10 marigold, repeated many times).

Fourth, there are early flowering period, full flowering period and withering period, and the specific dates should be recorded clearly and completely. Note that the data in the experimental record must be clear, such as "6 days" and "23 hours", and there should be no vague data such as "over 1 week" and "over 10 days". Otherwise, what is the basis of "the thicker the rare earth, the longer the flowering period"?

(Selected from Science and Technology for Middle Schools, No.4, 1994)

Second, the whole composition

Choose your own topic, and try to use your recent free time (half a month or a month) to write a short article on natural science.

Choosing a topic is very important. You can combine your own study and research on a subject that you are particularly interested in, or combine the research activities of extracurricular interest groups in this subject, or choose a topic whose research scope and depth are suitable for your own level and conditions according to your usual observation and research on a natural phenomenon. Then refer to some requirements and matters needing attention put forward in this paper, carefully collect and analyze materials, extract some valuable opinions, arrange appropriate structures, draft and revise them quickly, and finally copy them carefully. At the end of the paper, examples are attached for reference; You can also read some newly published scientific papers in newspapers and periodicals in combination with extracurricular reading.

The following topics are for reference:

1. Causes and prevention of sandstorms

2. Discussion on the pollution problem of ×× River

3. How to prevent land desertification

4. Also talk about reverence for life

5. Analyze the biological chain