CN102986355A - Precise nitrogen application method aiming at flue-cured tobacco - Google Patents

Abstract

The invention discloses a precise nitrogen fertilization method for flue-cured tobacco, the method is at the seedling stage of flue-cured tobacco growth, when the SPAD value is less than 38, the amount of nitrogen fertilizer used is 25-30kg/ ^hm2 ; at the root extension stage of flue-cured tobacco growth , when the SPAD value is less than 42.5, the nitrogen fertilizer application amount is 30-35kg/hm ² ; in the cluster stage of flue-cured tobacco growth, when the SPAD value is less than 44, the nitrogen fertilizer application amount is 25-30kg/hm ² ; For a long time, when the SPAD value is less than 46.5, the nitrogen application rate is 25-30kg/hm ² ; when it is greater than or equal to the SPAD threshold value, no nitrogen is applied; the total nitrogen application rate during the entire growth period is below 110 kg/hm ² . The method of the present invention refines the optimum fertilization threshold to each growth period requiring fertilizer, and then judges whether fertilization is required by comparing the SPAD value of each growth period requiring fertilizer with the SPAD value of the optimum fertilization in the growth period. The invention further improves the accuracy of nitrogen fertilization to flue-cured tobacco, thereby greatly improving the utilization rate of nitrogen fertilizer and the yield and quality level of flue-cured tobacco.

Description

A precise nitrogen fertilization method for flue-cured tobacco

technical field

The invention belongs to the technical field of tobacco planting, and in particular relates to a precise nitrogen fertilization method for flue-cured tobacco.

Background technique

In the production of flue-cured tobacco in China, there are phenomena of excessive nitrogen application and late nitrogen application, which not only increase the production cost, but also cause the quality of tobacco leaves to decline. At the same time, the low efficiency of fertilizer use also causes a series of problems such as environmental pollution. The balanced fertilization technology of tobacco leaves developed in the last century has played a positive role in promoting the production of tobacco leaves in China. However, due to the lack of mineral nutrition matching the growth status of tobacco leaves, the balanced fertilization technology is difficult to effectively treat tobacco plants. Effective monitoring of nutrition and growth conditions will bring about blindness in fertilization.

Under the high temperature and rainy conditions in southern China, the nitrogen use efficiency is only 39.6%, and excessive nitrogen fertilizer application has a great negative impact on the quality of tobacco leaves. Therefore, it is of great significance to monitor the nitrogen nutrition status of tobacco plants in the field in real time and quickly, and then guide the topdressing nitrogen fertilizer in the field flue-cured tobacco according to the nitrogen abundance and deficiency status, which is of great significance for improving the nitrogen use efficiency and the yield and quality of tobacco leaves.

There are many methods for diagnosing the nitrogen nutrition status or abundance and deficiency of flue-cured tobacco. Among them, measuring the total nitrogen content of flue-cured tobacco leaves or plants is considered to be a relatively accurate method, but this method requires destructive sampling and laboratory analysis, and has obvious hysteresis.

The chlorophyll meter (soil plant analysis development, SPAD instrument) is used to diagnose the nitrogen nutrition status or abundance and deficiency status of flue-cured tobacco, which is fast, simple and non-destructive. It has received extensive attention in crop nutrition diagnosis in recent years. A lot of research has been done on the application of SPAD instrument to diagnose nitrogen nutrition status and guide nitrogen fertilizer application in rice, wheat, cotton, rape and other crops, and achieved good results.

In tobacco, although predecessors have carried out some preliminary work on the relationship between the SPAD value of flue-cured tobacco leaves, chlorophyll content, and total nitrogen content, and established a field fertilization method based on a SPAD instrument, they only judge the nitrogen content of flue-cured tobacco based on a single SPAD threshold. The surplus and deficiency of the content, although compared with the traditional farmer's fertilization method, has achieved better yield and quality, but there is still a great potential for improvement.

Contents of the invention

In order to overcome the limitations of the existing method for judging the nitrogen content of flue-cured tobacco based on a single SPAD threshold to determine the nitrogen application rate, the purpose of the present invention is to study the relationship between the SPAD value of flue-cured tobacco leaves at different growth stages and the yield and quality of flue-cured tobacco under different nitrogen levels. In order to establish the optimal nitrogen application threshold in different growth stages, and finally provide a precise nitrogen application method for flue-cured tobacco, so as to further improve the yield and quality of flue-cured tobacco.

The object of the present invention is achieved through the following technical solutions:

A precise nitrogen application method for flue-cured tobacco, comprising the following steps:

In the seedling stage of flue-cured tobacco growth, when the SPAD value is less than 38, the amount of nitrogen fertilizer used is 25-30kg/hm ² , and when the value is greater than or equal to 38, no nitrogen is applied;

In the rooting stage of flue-cured tobacco growth, when the SPAD value is less than 42.5, the nitrogen fertilizer application amount is 30-35kg/hm ² , and no nitrogen is applied when the value is greater than or equal to 42.5;

In the cluster stage of flue-cured tobacco growth, when the SPAD value is less than 44, the amount of nitrogen fertilizer used is 25-30kg/hm ² , and when the value is greater than or equal to 44, no nitrogen is applied;

In the prosperous period of flue-cured tobacco growth, when the SPAD value is less than 46.5, the nitrogen fertilizer application amount is 25-30kg/hm ² , and no nitrogen is applied when the value is greater than or equal to 46.5;

The total amount of nitrogen application throughout the growth period is below 110kg/hm ² .

The amount of fertilizer application depends on the measured SPAD value. When the measured SPAD value is closer to the appropriate threshold, the fertilization can be reduced, and when the measured SPAD value is farther away from the appropriate threshold, the fertilization needs to be increased. For example: at the seedling stage, if the measured SPAD value is 37, then the smaller application rate in the selection range is 25kg/hm ² , if the measured SPAD value is 30, then the larger application rate in the selection range is 30kg/hm ² .

Specifically, from transplanting to surviving, the tobacco seedlings are in the seedling stage; when the roots recover and grow, the leaves turn green, do not wither, and the heart leaves begin to grow, the tobacco seedlings are considered to be alive;

Tobacco seedlings from surviving to grouping are called rooting period;

When the plant reaches the standard of clusters, there are 12 to 13 leaves at this time, and the ratio of the width of the horizontal growth of the leaves to the height of the vertical growth is about 2:1. When the shape is hemispherical, it is the cluster stage;

Plants from clusters to buds are called flourishing for a long time.

Determination of SPAD value: After transplanting, respectively at the seedling stage, rooting stage, cluster stage and flourishing stage of the tobacco plants, select the tobacco plants with the same growth, and wash the third fully expanded functional leaf with deionized water. The middle part was wiped dry with cotton cloth, and the SPAD value was measured by SPAD-502. The measurement site was the SPAD value of the middle part of the fully expanded leaf, and each leaf was measured 4 times. 10 strains were measured in each plot, and the average value was taken as the SPAD value of the plot. The sampling time is 9 am.

In the above method, the determination of the SPAD threshold is well-founded. The key period of fertilization of flue-cured tobacco is the seedling stage, the rooting stage, the cluster stage and the vigorous stage. In the literature (Wang Wei, Chen Jianjun, Lv Yonghua, et al. Research on Nitrogen Nutrition Diagnosis and Precision Fertilization Mode in Flue-cured Tobacco [J]. Journal of Agricultural Engineering, 2012, 28(9): 77-84.), through different nitrogen application rates The regression analysis between the average SPAD value of the top third leaf and the output value of tobacco leaves during the critical period of fertilization showed that the SPAD average value of the leaves at each growth stage and the output value showed an obvious quadratic curve relationship, and on the 28th day (returning seedling stage), the highest The nitrogen application rate corresponding to the output value is 110kg/hm ² , and the SPAD value is 38; on the 35th day (deep rooting stage), the nitrogen application rate corresponding to the highest output value is 110 kg/hm ² , and the SPAD value is 42; on the 42nd day (group tree stage) , the nitrogen application rate corresponding to the highest output value is 110kg/hm ² , and the SPAD value is 44; on the 49th day (long-term prosperity), the nitrogen application rate corresponding to the highest output value is 110kg/hm ² , and the SPAD value is 46.5. Therefore, the optimum nitrogen SPAD threshold for the seedling stage is 38, the optimum nitrogen SPAD threshold for the rooting stage is 42.5, the optimal nitrogen SPAD threshold for the tree cluster stage is 44, and the optimum nitrogen SPAD threshold for the long-term growth period is 46.5, and The maximum amount of nitrogen applied throughout the growth period should not exceed 110kg/hm ² .

Compared with the prior art, the present invention has the following advantages and effects:

The method of the present invention overcomes the limitation of the existing method of judging the nitrogen content of flue-cured tobacco based on a single SPAD threshold to determine the amount of nitrogen application, and refines the optimal fertilization threshold to each growth period requiring fertilizer. The SPAD value of the growth period is compared with the best fertilization SPAD value of the growth period, and then it is judged whether fertilization is needed. The invention further improves the accuracy of nitrogen fertilization to flue-cured tobacco, thereby greatly improving the utilization rate of nitrogen fertilizer and the yield and quality level of flue-cured tobacco.

Detailed ways

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Example

1. Experimental design

The test was carried out in Xihe Village, Dapu County, Meizhou City, Guangdong Province in 2012. The demonstration test of the present invention was carried out. The test set up 3 nitrogen application methods: respectively, the local traditional farm nitrogen application method (NH), and the singleness threshold of S=43 The nitrogen application method (SZ-1) guided by the SPAD instrument and the nitrogen application method (SZ-2) of the present invention, each treatment experiment was repeated 3 times, arranged in random blocks, a total of 18 plots, 60 plants were planted in each plot, and four weeks A protection line is set up, and other management measures are carried out according to the standardized production requirements of high-quality flue-cured tobacco. The basic physical and chemical properties of the soil in the test site are listed in Table 1.

Table 1 The basic physical and chemical properties of the soil in the test site

2. Determination of SPAD value

At the stage of returning seedlings, rooting stage, grouping stage and flourishing stage, select tobacco plants with the same growth respectively, wash the middle part of the third fully expanded functional leaf from top to bottom with deionized water, and dry it with cotton cloth. The SPAD value of SPAD-502 was measured 4 times for each leaf, and the average value was taken as the SPAD value of the leaf. Ten plants were measured for each plot, and the average value was taken as the SPAD value of the plot. The sampling time is also at 9 am.

3. Fertilization method

The nitrogen fertilizer application amount and application period of the three nitrogen fertilization methods are shown in Table 2, where the amounts of P ₂ O ₅ and K ₂ O are fixed. Fertilizer source is tobacco special compound fertilizer (NP ₂ O ₅ -K ₂ O: 13-9-14), superphosphate (P ₂ O ₅ : 12%), potassium sulfate (K ₂ O: 50%), potassium nitrate (NK ₂ O: 13.5-44.5), ammonium bicarbonate (N: 17.7%), rapeseed bran (NP ₂ O ₅ -K ₂ O: 5.2-1.4-1.3).

(1) Fertilization of the NH group: the amount of nitrogen applied to the base fertilizer was 110kg/hm ² ; and the topdressing nitrogen was 18kg/hm ² at 20d, 40d, and 80d after transplanting respectively.

(2) Fertilization of SZ-1: Based on the SPAD instrument precision nitrogen fertilization mode (SPAD threshold value is 43), 17-52 days after transplanting, use SPAD-502 to measure the SPAD value of the treated tobacco plants every 7 days. When the average value is less than the threshold value of 43, topdressing nitrogen fertilizer (before 52 days after transplanting, topdressing pure nitrogen 30kg/hm ² ; after 52 days, topdressing pure nitrogen 20kg/hm ² ) The amount of nitrogen should be controlled at 110kg/hm ² .

(3) Fertilization of SZ-2: Based on the precise nitrogen fertilization mode of the SPAD instrument, after transplanting, the tobacco seedlings enter the seedling returning stage, the rooting stage, the cluster stage and the vigorous stage (the fertilization growth period is determined by the actual growth of the local tobacco seedlings. determined), the SPAD value of the once-treated tobacco plants was measured with SPAD-502. When the SPAD value is less than 38 at the seedling stage, the nitrogen fertilizer application rate is 30-35kg/hm ² , and no nitrogen is applied when it is greater than or equal to 38; at the rooting stage, when the SPAD value is less than 42.5, the nitrogen fertilizer application rate is 30-35kg/hm ^2. No nitrogen application when the SPAD value is greater than or equal to 42.5; when the SPAD value is less than 44 in the group tree period, the nitrogen fertilizer application amount is 25-30kg/hm ² , and no nitrogen application is greater than or equal to 44; when the SPAD value is less than 46.5 in the flourishing period, The amount of nitrogen fertilizer used is 25-30kg/hm ² , and no nitrogen is applied when it is greater than or equal to 46.5; the amount of fertilizer application depends on the measured SPAD value. Fertilization needs to be increased when it is farther away from the optimum threshold. For example: at the seedling stage, if the measured SPAD value is 37, then the smaller application rate in the selection range is 25kg/hm ² , if the measured SPAD value is 30, then the larger application rate in the selection range is 30kg/hm ² . However, the total nitrogen application rate in the whole growth period should be controlled at 110kg/hm ² .

Table 2 Nitrogen fertilizer application amount and application period (Dapu area, Meizhou)

4. Test results

The test results are shown in Table 3. It can be seen from Table 3 that the yield and value of tobacco leaves show great differences under different nitrogen application methods: the yield and value of tobacco leaves are the largest in SZ-2, followed by SZ-1, and the smallest in NH. There were significant differences in yield and output value among the treatments, and the yield and output value of SZ-2 increased by about 28.32% and 37.60% compared with the local production level, and increased by about 20.9% and 17.9% compared with SZ-1. It can be clearly seen from the above data that the method of the present invention can bring about a comparative improvement in the yield and quality of flue-cured tobacco.

Table 3 Based on the real-time diagnosis of nitrogen nutrition in flue-cured tobacco by SPAD instrument and the experimental yield and output value of precise fertilization mode

Note: This variance analysis adopts Duncan's new bipolar method, "NH" represents the local production level, "SZ-1" is the old fertilization method based on a single SPAD threshold S=43, and "SZ-2" is the new fertilization method of the present invention method.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (2)

1. A precise nitrogen application method for flue-cured tobacco, characterized in that it comprises the following steps: In the seedling stage of flue-cured tobacco growth, when the SPAD value is less than 38, the amount of nitrogen fertilizer used is 25-30kg/hm ² , and when the value is greater than or equal to 38, no nitrogen is applied; In the rooting stage of flue-cured tobacco growth, when the SPAD value is less than 42.5, the nitrogen fertilizer application amount is 30-35kg/hm ² , and no nitrogen is applied when the value is greater than or equal to 42.5; In the cluster stage of flue-cured tobacco growth, when the SPAD value is less than 44, the amount of nitrogen fertilizer used is 25-30kg/hm ² , and when the value is greater than or equal to 44, no nitrogen is applied; In the prosperous period of flue-cured tobacco growth, when the SPAD value is less than 46.5, the nitrogen fertilizer application amount is 25-30kg/hm ² , and no nitrogen is applied when the value is greater than or equal to 46.5; The total amount of nitrogen application throughout the growth period is below 110kg/hm ² . 2. The precise nitrogen fertilization method for flue-cured tobacco according to claim 1, characterized in that: the SPAD value of flue-cured tobacco is measured in this way: after transplanting, it is respectively at the seedling stage, rooting stage, and cluster stage of the tobacco plant. For a long period of prosperity, select tobacco plants with the same growth, wash the middle part of the third fully expanded functional leaf with deionized water, dry it with cotton cloth, and measure its SPAD value with SPAD-502. The measurement site is the SPAD in the middle of the fully expanded leaf value, each leaf was measured 4 times; 10 plants were measured in each plot, and the average value was taken as the SPAD value of the plot; the sampling time was 9 o'clock in the morning.