Effects of Soil Temperature and Soil Moisture on Various Growth Traits of Seedlings in Nursery Stage

Recently, a soil moisture temperature recorder was used to record the effects of composite conditions of soil temperature and soil moisture on the growth and various characteristics of seedlings. At the same time, these seedlings were also studied for their low temperature activity after transplanting at low water temperature.

In 1968 and 1969, tests were carried out according to the same design. The treatments were listed in the following table: six treatments for temperature conditions, four treatments for soil moisture conditions, and a total of 24 treatments. The test cultivar was a rice variety named Nonglin 25, which was planted in a test basin with an area of ​​1/5Q00 acres (100 meters per acre). Each pot was filled with the same amount of air-dried fine soil (wet field submergence Clay soil type, liquid limit moisture content of about 72%, plastic limit about JS / p, full-layer fertilization sulfuric acid by 2 grams, superphosphate 4 grams, potassium chloride 2 grams, with germination seeds to 2 X 2 cm In order to promote germination, it was initially cultivated in a glass room, and when it reached about 2,5 leaf ages, it was moved to an artificial climate chamber for different temperature treatments. The test pots were placed in a constant temperature water bath and the soil temperature in the pots was controlled by adjusting the water temperature in the pots to maintain the temperature of each treatment. From the age of the leaves up to about 1,5, different soil moisture treatments were started, according to the soils treated Moisture content is adjusted according to the gravimetric method, in principle, once a day. Before the different temperature treatments are started, the soil surface is covered with styrofoam particles, so that the temperature and the ground temperature are isolated from each other, and the soil surface moisture is controlled to maintain the ground temperature. The soil moisture distribution is stable and reaches 6,5p-r age The end of treatment, investigation of various characteristics of seedlings, and some transplanted seedlings immediately to the temperature of 1G °C, water temperature 1 °C conditions, after low temperature treatment to day, pull out rice seedlings, determine the number of hair roots, the longest rooting Length, number of leaves, and leaf age schedule.Test Results and Discussion The results of 1968 and 1969 were basically the same, so only the 1969 results were reported.

First, the impact on the speed of leaf extraction The test began from the 1,5 leaf age soil moisture treatment, from the 2,5 leaf age temperature treatment, to the end of 6.5 leaf treatment, so the processing date varies depending on the processing conditions, such as Table 1 As shown, the required number of days (temperature treatment days) from 2,5 leaf-ages to 6,5 leaf-ages is 11 to 44 days, a large difference. Under relatively low temperature conditions, temperature conditions have a greater impact on the increase in leaf age; soil moisture is the percentage of saturated water capacity. Under high temperature conditions, the soil moisture condition is greater than the temperature. It has been confirmed that the leaf extraction speed is determined to a large extent by the temperature conditions (especially the temperature conditions near the growth point), which was confirmed again in this experiment. However, it should be noted that, under relatively high temperature conditions, the effect of soil moisture conditions exceeds the temperature conditions. Regarding this issue, it is considered that the physiological effects of the seedlings under high-temperature conditions are higher than those under low-temperature conditions, the daily water absorption and transpiration are significantly increased, and because the test regulates soil moisture regularly (in principle, every morning, 9 Point), which causes large changes in the daily soil moisture content of high-temperature treatment are all related. Although it can be considered that the effect of soil moisture conditions is enhanced at high temperatures, it is necessary to continue the discussion to clarify its causes. A variety of external morphological characteristics were investigated for G- and 5-leaf seedlings. The results of the survey showed that temperature and soil conditions have an effect on the seedling height, but the temperature conditions are slightly stronger. In particular, the treatment with a soil moisture content of 100% is strongly influenced by the temperature conditions, and the gap between the maximum and the minimum of the seedling height is nearly 20 cm. When soil moisture decreases, the influence of temperature conditions also decreases. In the treatment with a soil moisture content of 40%, the difference between the maximum and minimum values ​​was reduced to 9 cm. On the other hand, under the condition that the seedling height is easy to grow, the effect of soil moisture conditions is strong. For example, the temperature of 31°C and the ground temperature of 36°C are the maximum and minimum heights of seedlings due to different soil moisture treatments. The gap between the two is 12 centimeters. However, under conditions where seedling height is not easily increased, such as temperatures of 31°C and ground temperature of 36°C, the difference in seedling height due to treatment of soil moisture is only 3 cm.

Second, soil moisture conditions have a strong influence on the number of roots. In the treatment with a soil moisture content of 100%, there were 30-35 roots, and in the treatment with a soil moisture content of 40%, there were only 15 roots. However, the term “root number” here refers to a primary root that has been extended to 5 mm or more, and does not include a very short primary root that has just grown from the stem base. The number of roots of a rice plant that differentiates at the same node is roughly the same, but soil moisture has a strong influence on the development of roots, so when investigating the number of roots that have grown to more than 5 mm, each treatment room will There are significant differences, which is noteworthy. For example, when observing the development of roots, most of the roots that are likely to emerge, despite their high soil moisture content, are able to fully elongate, but the roots of the branches are poorly developed, and under conditions of low soil moisture content, Of the possible roots, only a few roots can elongate, but the development of branch roots is extremely good. Since the rest of the roots are in a state of elongation and development, the number of extremely short stem bases is much higher. . Elongated roots are very easy to pull off during pullout, and those very short roots on the stem base can be transplanted to Honda without damage and immediately begin to elongate in Honda, so the seedlings survive well. It can be seen from the above that soil moisture conditions in Putian have significant effects on the elongation and development of roots, and there is a close relationship between seedling survival in Honda.

In addition, the temperature and soil moisture conditions also have a considerable impact on the fractional millet, with more tillers at lower temperatures and less millet at higher temperatures. However, regardless of the temperature, the tillers with a soil moisture content of 40% had the lowest tillers. For soil moisture conditions with the highest number of tillers under different temperature conditions, treatment with 100% soil moisture content at low ground temperature (1°C-21°C); and high soil temperature (26°C-36°C) The soil moisture content is 80% of the treatment.

The above test results, in addition to the fact that the temperature condition has an effect on the external morphological characteristics of the seedlings, also show that the soil moisture conditions also have a considerable impact, especially the number of roots affected by soil moisture conditions is extremely strong. There have been disputes in the past on the relationship between the quality of dry seedlings and water-based seedlings in the trials on seedling raising, but few tests have been carried out on the method of soil moisture management for early-rising seedlings. From the above, it can be seen that due to the different management methods of soil water in Putian, the differences in the growth and quality of the seedlings will be considerable, which shows the importance of the temperature management of Putian and proper soil moisture management for the cultivation of Zhuang.

Third, the impact of thousands of substances

The results of investigations on the above-ground dry matter weight, root dry matter weight, and the average daily dry matter increase during the treatment period for 6.5-leaf seedlings showed that the ground temperature had a large influence on the dry matter weight, and the above-ground and root weights were treated at 21°C. It is the largest, while the floor temperature is 36'°C minimum. The effect of soil moisture conditions is relatively small, so with the reduction of soil moisture, dry matter weight tends to decrease only slightly. Temperature and soil moisture conditions have an impact on the average daily dry matter increase. In the temperature condition, the most basic treatment at the ground temperature of 16°C is followed by the treatment at the ground temperature of 36°C. In the soil moisture condition, the increase in soil moisture content is 100%. When the soil moisture content decreases, the average daily dry matter increase also decreases. The temperature of 21°C and the ground temperature of 26°C are smaller than the treatment temperature of 31°C and ground temperature of 26°C. This is similar to the treatment of temperature 21°C and ground temperature 26°C described below, which may be somewhat related to the increase or decrease of nitrogen and carbohydrate content in other treatments. However, the exact reason for this is not known. Although the effect of soil moisture on the increase of dry matter is considerable, the effect of soil moisture conditions is barely visible at the age of 6.5 leaves. This is because soil moisture conditions also affect the speed of leaf extraction. In the treatment with a small average daily dry matter increase, the leaf drawing speed is also slow, and there is a tendency to prolong the number of days required to reach the same leaf age. Therefore, when comparing with the same leaf age, there is no big difference in the final weight. As for the above-mentioned treatment at 21°C, the reason why the dry matter weight is the largest is that the average daily dry matter increase is large, and the number of fertility days is longer.

In order to study the suitable environmental conditions required for the cultivation of strong and strong maggots, seedlings were separately cultivated under the combined treatments of six temperature conditions and four soil moisture conditions. When the six and five-leaf ages were reached, various characteristics of the seedlings were investigated. Another part of the seedlings was transplanted to a low water temperature condition to investigate its survival status after 10 days.

Soil moisture temperature tester test report results are as follows:

1. At relatively low temperature conditions, the temperature conditions have a greater effect on the speed of leaf extraction than soil moisture conditions, but under high temperature conditions, the soil moisture conditions have a greater influence than the temperature conditions.

2. For the seedling height, dry matter weight, nitrogen content%, carbohydrate content%, the temperature conditions than the soil moisture conditions.

3. The root number and seedling moisture content, soil moisture conditions than the temperature conditions, and with the soil moisture content increases in direct proportion.

4. The diversity number is affected by the temperature conditions and the soil moisture conditions. Under the condition of low ground temperature 16°C-21°C), the number of tillers is the highest when the soil moisture content is 100%, and the treatment concentration is 80% when the soil moisture content is 26°C-36°C. The most.

5. The conditions for cultivating seedlings that can survive well at low temperatures are: ground temperature 16 °C, soil moisture content 60%, local temperature above 21 °C, soil moisture content 80%

6. Conditions that lead to poor survival are: ground temperature 28°C or 31'C, soil moisture content 80% 0

From this 1 year survey, we can see that soil moisture provides a good guarantee for the vigorous growth of plants, especially when the temperature is higher, and the growth of plant seedlings is more important than the soil. Moisture management.