TWI856871B - Method for culturing lactuca sativa using potassium-free medium - Google Patents

Abstract

A potassium-free medium is used for culturing a plant of Lactuca sativa, reducing potassium ion level of the plant of Lactuca sativa. Each liter of the potassium-free medium comprises: 84.0 mg of NO₃-N, 63.0 mg of NH₄-N, 15.4 mg of phosphorus (P), 0.0 mg of potassium (K), 40.0 mg of calcium (Ca), 12.2 mg of magnesium (Mg) and 16.2 mg of sulfur (S). A method for culturing the plant of Lactuca sativa using the potassium-free medium is also disclosed.

Description

Lettuce cultivation method using potassium-free culture medium

The present invention relates to a potassium-free culture solution, in particular to a potassium-free culture solution for culturing lettuce. The present invention also relates to a method for culturing lettuce using the potassium-free culture solution.

Chronic kidney disease (CKD), also known as chronic kidney failure, is defined as kidney damage, i.e. glomerular filtration rate (GFR) less than 60mL/min/1.73m ² ; abnormalities found in blood tests, urine tests or imaging tests; and a history of more than three months. When the glomerular filtration rate drops to less than 15mL/min/1.73m ² , it means that the patient's kidneys cannot function normally and hemodialysis (commonly known as dialysis) is needed to replace the kidney's function.

Patients undergoing hemodialysis must strictly control their intake of potassium-containing foods. Therefore, the intake of leafy vegetables containing high amounts of potassium ions will be strictly restricted. They must be blanched to remove potassium ions before they can be eaten. However, blanched leafy vegetables not only taste bad, but also have their nutritional components destroyed. In view of this, a low-potassium culture method for lettuce and a culture solution formula for use should indeed be provided.

In order to solve the above problems, the main purpose of the present invention is to provide a potassium-free culture solution for culturing low-potassium lettuce.

Another object of the present invention is to provide a method for culturing low-potassium lettuce using the potassium-free culture solution as described above.

The potassium-free culture solution for reducing the potassium ion content of lettuce of the present invention contains: 84.0 mg of nitrate nitrogen, 63.0 mg of ammonium salt nitrogen, 15.4 mg of phosphorus, 0.0 mg of potassium, 40.0 mg of calcium, 12.2 mg of magnesium and 16.2 mg of sulfur per liter. In addition, the potassium-free culture solution can also contain: 3.2 mg of iron, 0.5 mg of manganese, 0.02 mg of copper, 0.05 mg of zinc, 0.01 mg of molybdenum and 1.3 mg of sodium per liter.

Based on the same technical concept, the lettuce cultivation method of the present invention comprises: sowing a lettuce seed to obtain a lettuce plant; and culturing the lettuce plant with a potassium-containing culture solution for a culture period, and then culturing the lettuce plant with a potassium-free culture solution as described above for a treatment period; wherein the total number of days of the culture period and the treatment period is 35 days, and the number of days of the treatment period is between 8 and 12 days. Preferably, the number of days of the treatment period is 12 days.

Accordingly, by culturing the lettuce plant with the potassium-free culture solution, the underground growth of the lettuce plant can be inhibited, thereby reducing the potassium ion concentration in the aboveground part of the lettuce plant, so as to provide a source of leafy vegetables for hemodialysis patients, which is the effect of the present invention.

[Figure 1] Experimental design of the present invention.

〔Figure 2〕The effect of different potassium-free culture medium culture days on the growth of lettuce (bar=10cm).

In order to make the above and other purposes, features and advantages of the present invention more clearly understandable, the following is a preferred embodiment of the present invention, and is described in detail with the accompanying drawings as follows: The "lettuce" referred to in the present invention is an annual or biennial herbaceous plant of the genus Lactuca in the family Asteraceae. It can be divided into two major categories according to its appearance: head-bearing and non-head-bearing; and can be divided into round leaves, thin leaves, pointed leaves, horn leaves, sword leaves, lobed leaves, curly leaves, colorful leaves, etc. according to its leaf shape. The present invention uses shampoo green lettuce ( Lactuca sativa L.) for subsequent testing, but those with ordinary knowledge in the technical field to which the present invention belongs should be able to select different varieties of lettuce for testing and adjustment according to needs, and there is no limitation here.

The method for cultivating lettuce of the present invention is to sow a lettuce seed, and after a seedling period, a lettuce plant can be obtained. Then, during the cultivation period, the lettuce plant is cultivated with a potassium-containing culture solution, and during the treatment period, the lettuce plant is cultivated with a potassium-free culture solution.

Specifically, the lettuce seeds were purchased from Tak Shing Hong Co., Ltd. and sown in a culture dish at 20°C for 24 hours of germination [days after sowing (DAS) = 0]. The germinated lettuce seeds were transferred to a sponge medium (soaked in water and then transferred to a potassium-containing culture solution; DAS = 1) to begin cultivation. During the seedling period (DAS 1-7), LED lamps (cool white, color temperature of 6500K, light intensity of 200μmol‧m ^-2 ‧s ^-1 ) were used for 24 hours of illumination, and the ambient temperature was kept constant at 25°C.

The chemicals used in the potassium-containing culture solution are as follows: potassium nitrate (KNO ₃ ), ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ), magnesium sulfate (MgSO ₄ ‧7H ₂ O), sodium ferric ethylenediaminetetraacetate (C ₁₀ H ₁₂ N ₂ NaFeO ₈ ), calcium nitrate (Ca(NO ₃ ) ₂ ‧4H ₂ O), manganese sulfate (MnSO ₄ ‧H ₂ O), boric acid (H ₃ BO ₃ ), copper sulfate (CuSO ₄ ‧5H ₂ O), zinc sulfate (ZnSO ₄ ‧7H ₂ O) and sodium molybdate (Na ₂ MoO ₄ ‧2H ₂ O), so that each liter of the potassium-containing culture solution contains: 84.0 mg of nitrate nitrogen (NO ₃ -N), 63.0mg of ammonium saline nitrogen (NH ₄ -N), 15.4mg of phosphorus, 156.0mg of potassium, 40.0mg of calcium, 12.2mg of magnesium and 16.2mg of sulfur; in addition, each liter of potassium-containing culture medium also contains trace elements such as 3.2mg of iron, 0.5mg of manganese, 0.02mg of copper, 0.05mg of zinc, 0.01mg of molybdenum and 1.3mg of sodium. During the culture process, 1N sodium hydroxide (NaOH) was used to adjust the pH value of the potassium-containing culture solution to 6.0±0.2, and the conductivity of the potassium-containing culture solution was maintained at 1.2±0.2mS‧cm ^-1 .

Then, on the 8th day after sowing (DAS=8), the culture period begins. The culture solution used is the same potassium-containing culture solution as mentioned above. The number of days in the culture period can be between 23 and 27 days according to demand. The difference between the culture conditions in the above-mentioned seedling period is that the light cycle is adjusted to 16 hours of light period and 8 hours of dark period, and the temperature in the light period is maintained at 25℃, and the temperature in the dark period is set to 20℃.

After the culture period, the treatment period begins. The culture medium used at this time is the potassium-free culture medium of the present invention. The number of days in the treatment period can be between 8 and 12 days according to demand. It is only necessary to ensure that the total number of days in the treatment period and the culture period is 35 days.

The potassium-free culture medium uses similar chemicals to the potassium-containing culture medium, except that ammonium nitrate (NH ₄ NO ₃ ) replaces potassium nitrate (KNO ₃ ), so that each liter of potassium-free culture medium contains: 84.0 mg of nitrate nitrogen (NO ₃ -N), 63.0 mg of ammonium salt nitrogen (NH ₄ -N), 15.4mg of phosphorus, 0.0mg of potassium, 40.0mg of calcium, 12.2mg of magnesium and 16.2mg of sulfur; in addition, each liter of potassium-free culture medium also contains trace elements such as 3.2mg of iron, 0.5mg of manganese, 0.02mg of copper, 0.05mg of zinc, 0.01mg of molybdenum and 1.3mg of sodium. During the culture process, 1N sodium hydroxide (NaOH) was used to adjust the pH value of the potassium-free culture medium to 6.0±0.2, and the conductivity of the potassium-free culture medium was maintained at 1.2±0.2mS‧cm ^-1 .

In order to prove that the potassium concentration of the lettuce plants can be effectively reduced by culturing the lettuce plants with the potassium-free culture solution during the treatment period, the following test was conducted: Please refer to Figure 1. After 7 days of seedling period, the lettuce plants were divided into 6K group (control group, i.e., no treatment period), 8d group, 10d group and 12d group (all experimental groups, with treatment periods of 8, 10 and 12 days respectively). The lettuce plants were collected on the 43rd day after sowing (DAS=43). The aboveground and underground parts are shown in Figure 2, indicating that the treatment period will inhibit the growth of both the aboveground and underground parts.

Then, the fresh weight, yield and fresh weight of the aboveground parts were analyzed and recorded in Table 1 [those marked with different letters represent significant differences ( P <0.05)].

^z：地上部鮮重相對值=地上部鮮重/地上部鮮重_6K ^y：地下部鮮重相對值=地下部鮮重/地下部鮮重_6K

^z : Relative value of aboveground fresh weight = aboveground fresh weight/aboveground fresh weight_6K ^y : Relative value of underground fresh weight = underground fresh weight/underground fresh weight_6K

As shown in Table 1, the fresh weight of the aboveground part of the 8d, 10d, and 12d treatment groups decreased, and the ratio of the underground part to the aboveground part also decreased, indicating that the growth of the root system was inhibited.

The contents of ammonium ion (NH ₄ ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), nitrate ion (NO ₃ ^- ), calcium ion (Ca ²⁺ ) and magnesium ion (Mg ²⁺ ) in the aboveground part were also analyzed and are recorded in Table 2 below [those marked with different English letters represent significant differences ( P <0.05)].

As shown in Table 2, the treatment period of 8d, 10d, and 12d can significantly reduce the potassium, nitrate, and calcium content in the aboveground parts. It can be calculated that the potassium concentration in the aboveground parts can be reduced by 58%, 77%, and 84% after using the potassium-free culture solution for 8 days, 10 days, and 12 days, respectively.

In summary, by culturing the lettuce plant with the potassium-free culture solution, the underground growth of the lettuce plant can be inhibited, thereby reducing the potassium ion concentration in the aboveground part of the lettuce plant, so as to provide a source of leafy vegetables for hemodialysis patients, which is the effect of the present invention.

Although the present invention has been disclosed using the above preferred embodiments, they are not intended to limit the present invention. Any person skilled in the art may make various changes and modifications to the above embodiments within the spirit and scope of the present invention, and these changes and modifications are still within the technical scope protected by the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of the patent application attached hereto.

Claims (2)

A method for cultivating lettuce, comprising: sowing a lettuce seed to obtain a lettuce plant; and cultivating the lettuce plant in a potassium-containing culture solution for 23 days, and then cultivating the lettuce plant in a potassium-free culture solution for 12 days; wherein each liter of the potassium-free culture solution contains: 84.0 mg of nitrate nitrogen, 63.0 mg of ammonium salt nitrogen, 15.4 mg of phosphorus, 0.0 mg of potassium, 40.0 mg of calcium, 12.2 mg of magnesium and 16.2 mg of sulfur. The method for culturing lettuce as claimed in claim 1, wherein each liter of the potassium-free culture solution further comprises: 3.2 mg of iron, 0.5 mg of manganese, 0.02 mg of copper, 0.05 mg of zinc, 0.01 mg of molybdenum and 1.3 mg of sodium.