Author: Cheng Chang co-research group

Published by: Zhejiang China Tobacco Industry Co., Ltd. Technology Center

Chinese Core Journal: China Tobacco Science

Research Background:

Flue-cured tobacco is an economic crop that is harvested with tobacco leaves. Topping measures are taken in production to break the top advantage of tobacco plants, which is used to regulate plant growth and coordinate the direction of nutrient operation to ensure that tobacco leaves obtain sufficient nutrients to form yield. However, due to the disappearance of the top advantage, the endogenous hormone synthesis of the tobacco plant is blocked, and the metabolic center changes. At the same time, potassium returns to the root through the phloem after topping, causing potassium loss and potassium nutrient deficiency in the later stage of growth. Therefore, coordinating the sink-source relationship of tobacco plants after topping is a research hotspot in high-quality tobacco production. The existing researches mostly focus on the single application or simple combined application of exogenous hormones and potassium fertilizers. There are few studies on the combined application rates of exogenous hormones and potassium fertilizers, photosynthetic characteristics, organic potassium index, etc.

Research ideas:

Through field experiments, the flue-cured tobacco variety Yunyan 87 was used as the material, gibberellin was sprayed on the leaf surface on the day of topping, and potassium sulfate was applied to the roots at the same time. Based on the influence of photosynthetic parameters and organic potassium index, it is inferred that the appropriate gibberellin concentration is matched with the amount of potassium fertilizer to provide a theoretical basis for the implementation of high-quality tobacco production technical programs.

background knowledge:

1. The application of auxin and gibberellin by foreign aid can significantly increase potassium and reduce alkalinity, and coordinate chemical components;

2. Applying potassium fertilizer at the late stage of flue-cured tobacco growth and the middle leaf mature stage can effectively supplement the potassium nutrition of tobacco plants and increase the utilization rate of potassium;

3. Applying gibberellin and topdressing potassium fertilizer on the day of topping can stimulate the root system to absorb potassium from the soil and promote the quality of tobacco leaves.

Main results:

1: Effects of different treatments on the content of chlorophyll and carotenoids in tobacco leaves

The content of chlorophyll and carotenoid in tobacco leaves of each treatment increased by different amplitudes compared with CK, and the overall difference reached a significant level, indicating that spraying gibberellin on the leaf surface and applying potassium fertilizer on the root can effectively improve the physiological activity of the surface cells of the tobacco leaf and protect the ultrastructure of chloroplast Integrity, reduce the degree of lipid peroxidation of cell membrane, delay the decomposition of chlorophyll, and promote the absorption and utilization of light energy by tobacco leaves.

Figure Note: Effects of different treatments on the content of chlorophyll and carotenoids in tobacco leaves

Note: Different lowercase letters indicate significant differences at the 0.05 level.

2: Effects of different treatments on photosynthetic parameters of tobacco leaves

T1～T4 have a significant effect on the adjustment of gas exchange parameters Gs, Ci, Tr, all of which are increased in different ranges compared with CK. It may be that gibberellin and potassium fertilizer are beneficial to improve the physiological activity of tobacco leaves, regulate the movement of guard cells, and maintain a higher Gs; on the other hand, a higher Tr is beneficial to lower the surface temperature of tobacco leaves and further reduce heat dissipation. , So as to protect the photosynthetic machinery; and the increase in Ci content indicates that the mesophyll cells maintain a high gas exchange capacity with the outside. Therefore, the Pn of tobacco plants from T1 to T4 was significantly increased by 14.3%-27.7% compared with CK, indicating that gibberellin and potassium fertilizer can effectively improve tobacco leaf photosynthesis and promote the accumulation of more photosynthetic products.

Figure Note: Effects of different treatments on photosynthetic parameters of tobacco leaves

Table 1: The p.η2 value of gibberellin and potassium fertilizer and their interaction on photosynthetic pigments and photosynthetic parameters of flue-cured tobacco

Note: When 0.010.14 indicates a strong effect.

3: The influence of different treatments on the chemical composition of tobacco leaves

The content of reducing sugar and total sugar in T1～T4 tobacco leaves was significantly higher than that of CK, and the increase was 9.6%～19.1% and 5.1%～12.4% respectively. Compared with CK, the nicotine and total nitrogen content of T1～T4 tobacco leaves were significantly lower than that of CK. The reductions were 8.8%～21.6% and 6.5%～16.0%, respectively. The main factor for the increase of nicotine content; gibberellin can reduce the nicotine and total nitrogen content in tobacco leaves.

Table 2 Effects of different treatments on the content of chemical components in tobacco leaves

Table 3 The p.η2 value of gibberellin and potassium fertilizer and their interaction on the content of tobacco leaves

The combined application of gibberellin and potassium fertilizer can significantly increase the reducing sugar and total sugar content of tobacco leaves, and reduce the nicotine and total nitrogen content. There is no significant difference in the ratio of sugar to nicotine and nitrogen to nicotine between treatments, but it is slightly increased compared with CK, indicating that it is red. The result of mutual promotion of mycin and potassium fertilizer.

Table 4: Effects of different treatments on mineral elements, potassium to chlorine ratio and organic potassium index of flue-cured tobacco

Table 5 p.η2 test of gibberellin and potassium fertilizer and their interaction on the content of mineral elements, potassium-chlorine ratio and organic potassium index of tobacco leaves

in conclusion:

Gibberellin and potassium fertilizer have a moderate to strong effect on the photosynthetic performance, chemical composition and organic potassium index of flue-cured tobacco as a whole, but the contribution rate of variation of each component index is different, and the gibberellin factor is the main influencing factor. In addition, increased application of potassium fertilizer at the same level of gibberellin concentration and increased application of gibberellin at the same level of potassium fertilizer are beneficial to increase the content of chlorophyll and carotenoids in tobacco leaves; increase the net photosynthetic rate, stomatal conductance and other photosynthetic parameters of tobacco; coordinate tobacco leaves The chemical composition improves the organic potassium index.