小白菜的贮藏.docx

1、小白菜的贮藏小白菜的贮藏更新时间：2003-9-19来源：中国蔬菜网最适储存温度：0相对湿度：98%RH以上。采收后应尽快预冷。其最佳的储存条件为冰点以上，0左右、98100%RH，约可存放两周。储存温度高，菜叶易黄化及腐烂，储存寿命较短。储存温度（） 0 5 10 15 常温（20） 储存期限（天） 15-25 8-10 6-8 3-5 1 大白菜的贮藏更新时间：2003-9-19来源：中国蔬菜网最适储存温度：0相对湿度：98%RH以上结球白菜最佳的储存条件为0，95-100%RH，约可储存1.5-2个月。采收时受伤的白菜及病叶必须去除，储存环境中不可有乙烯存在。1%的低氧储存可以延长其储存

2、期限。储存温度（） 0 5 10 15 常温（25） 储存期限（天） 40-70 30-50 15-30 10-20 4-10 大白菜采后处理更新时间：2003-9-12来源：edisHandling Florida Vegetables: Cabbage 1Steve Sargent2Cabbage is grown in Florida under a wide variety of conditions but best quality is obtained during the cooler season of fall/winter/spring. Cabbage producti

3、on in Florida is intended for the fresh market in those areas of the U.S. unable to produce cabbage during the late fall/winter/spring. This publication is intended to assist the vegetable-handling industry to provide high quality fresh cabbage that is available, desirable, and nutritious for the co

4、nsuming public. Preplant Fertilizer Starter fertilizer. Current recommendations are only a fraction of the total seasonal fertilizer requirement, either liquid or dry, be applied in the bed as a starter fertilizer for drip irrigated crops. This starter fertilizer would contain all of the phosphorus

5、(P) and micronutrients and up to 40% of the nitrogen (N) and potassium (K). On soils testing very low in P and K, the starter can be broadcast or banded in the bed. If only small amounts of P and micronutirents are required, then it is normally better to band these materials. Bands should be placed

6、below the bed surface 2 to 4 inches and to the side of the plant row, but not between the drip tube and row. In most cropping situations, approximately 30-40 lb/acre of N and K would be sufficient in the starter fertilizer mixture. The amounts of P and micronutrients should be determined by a calibr

7、ated soil test. In situations where the soil test index for P is high to very high, then no P is required in the fertilizer. Phosphorus and micronutrients. In general, P and micronutrients are not recommended for simultaneous application in drip irrigation systems in Florida. This is because of the

8、possibility of precipitation of P and micronutrients or the P and calcium or magnesium in the well water. Research has shown that P can be successfully applied through drip irrigation systems with certain precautions (Rolston et al., 1981; Mikkelsen, 1989). However, if application of P is required d

9、uring the season (such as during cold periods), it should be injected alone. Acidification of the irrigation water to pH 4.0 to 5.0 might be needed to keep the P in solution during application, especially when using the high pH water from the Floridan aquifer. Acidification can be achieved by using

10、phosphoric, sulfuric, hydrochloric, or other acids to reduce the pH of the water. In summary, injection of P is possible and can be an efficient method of P application, however injection must be done with careful attention to water pH and is generally not recommended for Florida vegetables. Caution

11、: When acids must be diluted with water, always pour the acid into the container of water. Never pour water into acid because it will splatter when it contacts the acid. Micronutrient injection can present problems similar to those experienced with P injection. The key is to avoid precipitation even

12、ts. Potential problems with micronutrients are less severe compared to P because rates of application are normally much less with micronutrients than P. If micronutrients must be injected, then soluble forms, less subject to precipitation, such as chelates, should be used. Like P, micronutrients sho

13、uld be injected alone to avoid potential precipitation problems. Although there are serious problems and considerations with injecting P and micronutrients, there are several potential benefits from proper injection where water chemistry is suitable. Phosphorus and most micronutrients are relatively

14、 immobile in the soil so that generally only one or two applications are needed in a growing season. Also, in most Florida vegetable soils, only small amounts are needed. Research has shown that plant recovery of these nutrients can be increased when they are applied through the drip system (Rolston

15、 et al., 1981; Mikkelsen, 1989). This is probably due to resulting band-like application in the drip-irrigated zone where the nutrients are not widely mixed with the soil where fixation can occur. Although only a portion of the root zone would be exposed to the nutrients, research shows that not all

16、 of the root system needs to absorb the nutrient to benefit the plant. There have been some serious clogging problems in Florida from improperly managed P and micronutrient injections. This is why injecting P and micronutrients is not often practiced. If injections are required, proper procedures sh

17、ould be followed. Zero in-bed (preplant fertilizer). In some production systems where soils are relatively high in organic matter, micronutrients, P, and K, it is possible to grow successful crops with no in-bed fertilizer ( i.e. all fertilizer (nitrogen) applied through the drip-irrigation system).

18、 This is particularly attractive for areas in the state where growers experience soluble salt problems in the soils. Reducing the amount of dry fertilizer applied in the bed could potentially reduce soluble salt injury to young seedlings or transplants. The use of soluble N and P starter solutions w

19、ith the transplants might still be advantageous but these amounts of N and P are very small. Slow-release. For some crops such as strawberries, tomatoes, and peppers, benefit can be achieved from using slow-release fertilizers in the in-bed starter fertilizer mixture to provide an early season N sup

20、ply. Slow-release fertilizers are less subject to leaching during the early part of the season when the beds are wetted with subirrigation. Also, slow-release fertilizers have a lower salt index so they are less likely to damage young seedlings and transplants early in the season (Everett, 1977). Su

21、pplying 30-40 lb/acre of N from slow-release fertilizer, although more expensive, might be beneficial for these crops. It is important to select a slow-release fertilizer with a nutrient-release pattern appropriate for supplying N to the young crop. This practice is more important for fall crops whe

22、n frequent rain reduces the need for irrigation, yet fertilizer is still required by the young crop. Preplant fertilizer. Since preplant fertilizer is applied in small amounts, the most efficient application method is to band the fertilizer near the plant row. The fertilizer can be banded in the bed

23、 as dry or liquid material as the bed is formed and pressed. Incorporation of fertilizer by mixing it throughout the bed is acceptable if it will not be exposed to leaching or drying out. Any fertilizer placed in the bed before planting should be placed so that it will be least likely to leach, eith

24、er from rain coming through the holes in the plastic or from water applied with the drip irrigation tubing. This means that fertilizer applied in bands should be applied to the area of the bed outside of the tubing placement. The band should not be placed on the surface between the tubing and the ro

25、w because irrigation water from the tubing would have a tendency to move the fertilizer salts toward the plant where soluble salt injury could occur. Fertilizer bands should not be placed on the surface of the bed because they may dry out as the surface of the bed dries when the water table is lower

26、ed. Banded fertilizer should be placed 2 to 4 inches deep in the bed where it will remain in contact with moist soil, dissolve, and be available to the plants. In-bed fertilizer materials can use many fertilizer sources. Materials such as triple-superphosphate, ammonium nitrate, potassium chloride,

27、and potassium nitrate have worked well as starter fertilizers. After preplant fertilization, the remaining 60 to 80% of the N and K is applied in increments through the cropping season via the drip irrigation system. In some cases, growers apply some of this N and K in bands (hot-mix) on the surface

28、 of the bed. These growers feel they need a certain amount of fertilizer in the bands for rainy periods when they do not need to irrigate with the drip irrigation system. In most situations, hot-bands are not needed, and most often the fertilizer material in the hot-bands is not fully utilized by th

29、e crop (Figure 8) . This is because, in many cases, the hot-bands dry out after the water table is lowered, especially in the shoulder area. A significant amount of the N and K fertilizer in these hot-bands is then not available to the crop. If drip irrigation is being used for the injection of fert

30、ilizer materials, it is best to use the system to its fullest extent. This means injecting 60 to 80% of the N and K through the system. (Figure 8) . Injected Fertilizer Rates. On typical Florida sandy soils, in most situations injected fertilizers will consist only of N and K. The amount of N to use

31、 is determined by the crop nutrient requirement for N for that particular crop. This amount of N is recommended for each crop for each season. Specific recommendations for each crop are presented in SP 177 (Hochmuth and Hanlon, 1995) and in this publication for drip-irrigated crops. Recommendations

32、are under continual revision as more research results become available. The K amount to be injected is based on the soil test predicted amount of K required for the crop minus the amount that is applied in the bed preplant. For example, if the soil tested medium in K, perhaps only 100 lb of K 2 O fertilizer would be required for the season. If 20% of this K 2 O ( i.e. 20 lb) were applied in the bed as starter fertilizer, then 80 lb would be injected through the season. Sources. There are several sources of N and K that can be use