Study on the influencing factors of sowing and Seedling raising of Nelumbo nucifera

Study on the influencing factors of sowing and Seedling raising of Nelumbo nucifera

1 general situation of the experimental site

The experimental site is located in Shishan Village, Xunzhong Town, Dehua County, Quanzhou City, Fujian Province, latitude 25 °26 °58 "N, longitude 118 °15 °18" E, located in the low mountain and hilly area, 450 m above sea level, belonging to the subtropical mountain climate zone, with an average annual temperature of 19 ℃, frost-free period of 255 days, annual rainfall of 1 580.22 mm, annual relative humidity of 84%, annual sunshine hours of 2166 h, with obvious mountain climate characteristics, mild and humid, superior hydrothermal conditions. It is suitable for the growth of water lotus [10]. The previous crop in the experimental site was rice, and the sandy soil was not polluted by high toxic and high residual pesticides in the early stage.

2 materials and methods

2.1 Test material

The tested seeds were collected from Dehua County, Quanzhou City in October 2015. the mass of 1000 seeds was 62.5 g. The collected seeds are placed in a ventilated and dry place to dry in the shade, and then the dried seeds are stored in wet sand, a layer of sand. The humidity of the sand is that it will not spread out after being clutched by hand, and it will be turned every 10 to 15 days. And pay attention to maintain the temperature and humidity of storage to prevent seed mildew.

2.2 Test method

Sow the seeds in the seedbed, gently press into the soil, cover the surface with matrix and film arch shed, spray water to keep moisture, apply fully fermented organic fertilizer (sheep manure) as base fertilizer, and apply compound fertilizer (N15%, P15%, K15%) as topdressing. According to the characteristics of sowing and seedling raising and the growth status of seedlings, the effects of sowing density, soil covering substrate and soil covering thickness on the seedling raising effect in the field nursery were studied.

2.2.1 sowing density

Sowing density is one of the core contents affecting seedling raising. Seedling raising with different densities is designed to screen the best sowing density. The experiment adopted the sowing method of strip sowing, set 1m ~ 2 and 20 cm/ rows in each sample plot, and set 5 treatments of sowing density: 80,100,125,165,250 grains marked as Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ, repeated for 3 times, and covered with soil after sowing and fertilization.

2.2.2 soil cover matrix

Four treatments were set up: burning soil, red core soil, burning soil ∶ red core soil = 1 ∶ 2, burning soil ∶ red core soil = 2 ∶ 1, marked as S1, S2, S3, S4, soil thickness of 1 cm, plant spacing of 20 cm × 20 cm, 6 rows of 25 seeds per row, repeated 3 times.

2.2.3 thickness of soil cover

In the experiment, the burning soil ∶ red core soil = 2 ∶ 1 was used as the covering substrate, and the soil thickness was set at 0.5,1,2.0,3.0,4.0 cm respectively. The treatments were marked as F1, F2, F3, F4 and F5, and the row spacing was 20 cm × 20 cm. Each treatment had 6 rows with 25 seeds per row and repeated 3 times.

2.3 data processing and analysis

The data collection, analysis of variance and Duncan multiple comparison of the test results were carried out by DPS software.

3 results and analysis

3.1 effect of sowing density on germination and growth of alternanthera philoxeroides seeds

Sowing density is a key index that directly affects seedling quality and yield, and has a direct impact on seedling emergence rate, seedling height and basal diameter growth. this is because the water, nutrients and light provided by sowing substrate per unit area are limited. The increase of sowing density within a certain range can effectively increase the emergence rate, promote the growth of seedling height and basal diameter, and increase the quality and yield of qualified seedlings per unit area, but if the sowing density is too high, the seedlings are crowded, and the grabbing nutrition is limited. insufficient light and reduced photosynthesis not only reduces the germination rate, but also is not conducive to the height growth and basal diameter growth of seedlings. The quality and yield of qualified seedlings per unit area decreased directly.

The analysis of variance in Table 1 showed that there were significant differences in seedling emergence rate, seedling height and basal diameter among different sowing densities.

The multiple comparison of Duncan in Table 2 showed that there was no significant difference in seedling emergence rate among ① treatments except that there were significant differences between Ⅱ and Ⅰ, Ⅴ and Ⅳ, Ⅱ and Ⅲ, and the seedling emergence rate was the highest when the sowing density of Ⅰ was 165m-2. In terms of seedling height growth in ②, except between Ⅰ and Ⅴ, there were significant differences in seedling height among other treatments, and the seedling height was the highest when the sowing density of Ⅲ was 125 grains m ~ (- 2), and there were significant differences in basal diameter growth of ③, and the basal diameter was the thickest when the sowing density of Ⅰ was 165 grains m ~ (- 2). Therefore, considering all the influencing factors, the sowing density of alternanthera philoxeroides should be 125-165 grains.

Table 1 Variance analysis of emergence rate, seedling height and basal diameter of different sowing density

Note: * indicates significant difference at 0.05 level; * indicates extremely significant difference at 0.01 level (same below).

Table 2 multiple comparison of emergence rate, seedling height and basal diameter of different sowing densities

3.2 effects of soil-covered substrate on seed germination and growth of alternanthera philoxeroides

The analysis of variance in Table 3 showed that there were significant differences in seedling emergence rate, seedling height and basal diameter among different soil-covered substrates.

The multiple comparison of Duncan in Table 4 showed that there was a significant difference in seedling emergence rate among ① treatments, and the seedling emergence rate was the highest when ∶ red soil = 2 ∶ 1 was used as covering soil. The emergence rate of burning soil or red core soil alone is lower than that of the mixture of the two, because burning soil is a kind of soil matrix with high content of available nitrogen, phosphorus and potassium, which has good permeability and is not easy to consolidate. On the other hand, red soil has a certain ability to conserve water and fertilizer, but the disadvantage is that the soil is easy to harden, and the two are mixed in proportion to give full play to their advantages and optimize the proportion, so that the matrix has good water and fertilizer conservation, comprehensive nutrition, looseness and permeability, which is beneficial to the germination and growth of seeds. In terms of seedling height growth of ②, except that there was no significant difference between treatment S1 and treatment S2, there were significant differences in seedling height among other treatments, and the seedling height of ∶ red soil with 2 ∶ 1 was the highest. This is because the mixed use of burning soil and red core soil is easy to promote root growth, and the root system is well developed, which can effectively improve the ability of absorbing soil nutrients, thus promoting seedling height growth. in terms of basal diameter growth of ③, except that there is no significant difference between treatment S3 and treatment S1, the base diameter of other treatments is significantly different, and the base diameter of burning red soil ∶ = 2 ∶ 1 is the thickest. This is because the nutrient content of the covered soil matrix is different, the proportion of burning soil in the matrix is higher, the nutrient content of the soil is higher, which can effectively promote the basal diameter growth of seedlings. Therefore, considering all the influencing factors, it is better to choose fire-burning soil ∶ red soil = 2 ∶ 1 as the sowing covering medium.

Table 3 Variance analysis of emergence rate, seedling height and basal diameter of different soil-covered substrates

Table 4 multiple comparison of emergence rate, seedling height and basal diameter of different soil-covered substrates

3.3 effect of soil thickness on seed germination and growth of alternanthera philoxeroides

The variance analysis of table 5 shows that there are extremely significant differences in seedling emergence rate and seedling height among different soil thickness, but there is no significant difference in basal diameter growth.

Table 5 Variance analysis of emergence rate, seedling height and base diameter of different soil thickness

Table 6 multiple comparison of emergence rate, seedling height and base diameter of different soil thickness

The multiple comparison of Duncan in Table 6 showed that the emergence rate of ① was significantly different among other treatments except that there was no significant difference between F4 and F5, and the emergence rate was the highest when the thickness of soil cover was 2.0 cm. When the thickness of covered soil is in the range of 2.0 cm, the emergence rate increases with the increase of thickness, and when the thickness of covered soil exceeds 2.0 cm, the emergence rate begins to decrease with the increase of thickness. This is because after sowing, the covered soil is too thin, the seeds are easily washed out of the surface, exposed on the seedbed, lack of nutrients and water, affecting germination; while the covered soil is too thick, and the topsoil is easy to harden after watering, which leads to insufficient supply of oxygen for seed germination, respiratory obstruction, weak growth, and seedlings unable to push out of the soil surface, resulting in seed decay and lack of seedlings. In terms of seedling height growth in ②, there was no significant difference in seedling height between F1 and F5, and the seedling height was the highest when the soil thickness was 2.0 cm. Sowing and covering soil can not only provide medium protection for seeds, but also provide nutritional support for seeds and promote seed germination and high growth. In the process of seed germination and breaking soil growth, with the increase of soil thickness, the resistance increased, and the seedling height growth was limited, but after unearthed, it could promote seedling height growth with a certain thickness of soil support, while there was no significant difference in ③ basal diameter growth among different treatments, among which the basal diameter was the thickest when the covering soil thickness was 3.0cm. At the seedling stage of sowing and germination, the height growth of seedlings is stronger than that of basal diameter, and the thickness of soil cover has little effect on basal diameter growth temporarily. Therefore, considering all the influencing factors, the sowing soil thickness of Polygala paniculata should be 2.0-3.0 cm.

4 conclusion and discussion

Sowing density, soil cover substrate and soil cover thickness have important effects on seed germination and growth.

The main results were as follows: (1) when the sowing density was within the range of 80,165 grains m ~ (- 2), the seedling emergence rate, seedling height and basal diameter increased at first and then decreased with the increase of density. When the density was 165 m ~ (- 2), the emergence rate and basal diameter reached the highest value, while the seedling height reached the highest value when the density was 125 m ~ (- 2). This is related to the fact that density can cause interactions among plant individuals due to the forced allocation of growth resources, because the increase of density can directly lead to intraspecific competition, resulting in changes in individual plant growth and biomass in the population [11]. Therefore, when sowing and raising seedlings, it is appropriate to choose 125-165 grains of mmur2 as the best sowing density range.

(2) the selection of different soil-covered substrates had significant effects on the emergence rate, seedling height and basal diameter of water lotus seeds, which was related to the level of nutrients that could be absorbed by sowing seedlings. The seedling emergence rate, seedling height and basal diameter reached the highest when the covering soil substrate was ∶ red soil = 2 ∶ 1. Therefore, when sowing and raising seedlings, it is appropriate to choose burning soil ∶ red soil = 2 ∶ 1 as the best covering medium.

(3) because the seeds of Polygala paniculata are small and the ability of emergence and soil breaking is weak, the selection of soil cover thickness during sowing is very important. If the soil cover is too thin, the surface is prone to lack of water, which leads to the difficulty of seed germination. The seedling emergence rate, seedling height and basal diameter of alternanthera philoxeroides seedlings changed with the change of soil thickness when the covering soil thickness was between 0.5 and 4.0 cm. When the covering soil thickness was 2.0 cm, the seedling emergence rate and seedling height reached the highest, while the thickest cover soil thickness reached 3.0 cm. Therefore, considering the influence of various factors, 2.0-3.0 cm should be chosen as the best range of soil cover thickness.