番茄臍腐病Tomato disorder Blossom End Rot (BER).doc

Tomato disorder: Blossom End Rot (BER)IntroductionTomato has gradually become one of the most popular vegetables in the world. The global production of the tomato has reached to 145 million tons and it has shown a rising trend in recent years (Barickman,2014). The tomato production area keeps increasing year by year. However, because of the climate change stress and environmental pressure, the sensitivity of tomato limits the production area expansion as well (Jong et al., 2009). Diseases and disorders can definitely restrict the tomato yield. If there is no proper protective measures, some diseases like Blossom-End Rot, Late Blight and Physiological Leaf Roll/Curl can completely destroy the whole plant within two or three weeks time. Blossom-End Rot is a common physiological tomato disorder which can result in over 50% losses of the tomato production once the Blossom-End Rot spreads to the whole production site and without a promptlyeffectivetreatment (Ohlson et al., 2015). In the following, the Blossom-End Rot will be detailed discussed respectively in three parts: symptoms, causes and management.SymptomsThe incipient stage of Blossom End Rot (BER) often appears a small lesions area at the blossom end of the immature fruit. Soon after, the tiny lesions area starts to enlarge and turn to be watery and sunken. Finally, the affected tissue becomes a dark brown leathery necrosis placenta (Robbins, 1937; van Goor, 1968). Theoretically, at any period of the fruit development, BER can be successfully induced. However, in practice, the incidence of BER normally happens around the second week after the flowering period. The tomatoes with BER are relatively precocious and the fruits are normally smaller than healthy ones (DeKock et al., 1979). The basal part of the fruits may be most severely affected by the BER. After half part of the fruit is completely infected by the BER, the fruit may become concave and lead to a complete collapse destruction. In addition, there are two different types of BER. One is the external BER which has been mentioned above. Another one is known as the internal BER, it probably only affect the inside tissues of the fruits, for example the seeds and tomato walls may turn to gray and black under this circumstances, but the surface of the fruit may not be affected(Spurr, 1959).CauseInitially, it is believed that BER occurs when there is inadequacy Calcium to support the normal cell growth at the blossom-end of a tomato fruit (Suzuki et al., 2003). However, in 1995, Nonami et al. claimed that Ca2+ deficiency may not be a direct reason for the BER occurrence. Sufficient studies have shown that the Ca2+ concentration and distribution are similar between a healthy tomato fruit and an infected fruit at the BER incipient stage. On the other hand, even if there is sufficient Ca2+, the BER occurrence is still inevitable. In 2004, Taylor and Locascio demonstrated that the BER occurrence may be actually caused by the abiotic stress such as the intensive light, drought, salinity, ammonia nutrients and heat. The further researches also indicate that the environmental conditions may relatively interfere with the Ca2+ transport and uptake (Saure, 2001). With an increasing environmental stress and climate change pressure, the reactive oxygen species (ROS) are gradually increased and because of the high oxidative stress, the cells finally die.In addition, there are two major phytohormones have been revealed in these abiotic stress reactions: Bioactive gibberellins (GAs) and abscisic acid (ABA). According to various mechanisms, GAs may accelerate the BER incidence rates and promote cell death. However, the ABA is in an opposite direction, by means of promoting Ca2+ transportation, it decreases the plants susceptibility to these stress and successfully controls the cell expansion and membrane permeability to a reasonable range . According to the Barickman et al. (2014) research, the 500 mg L1 ABA foliar spray treatments can be classified as an alternative method to confront the BER problem. By increasing the Ca uptake of the tomato plants, it can successfully decrease the incidence of the BER.ManagementIn order to efficiently control the incidence of the BER development, a proper production site seems to be the first critical factor to be taken into consideration. The soil structure should be stable and porous. A well-drained soil structure is considerably important to prevent the water logging and hold adequate soil moisture. The soil pH should be maintained around 6.5, so that most of the nutrients can be smoothly absorbed by the tomato plants (Saure, 2001). Management practices should be followed up and supervised after seeding and transplanting. Composted manures should be applied before the planting so that these organic fertilizers can be gradually decomposed during the period of plant growth. On the other hand, the over fertilization may cause severe problems, for example, the tomato plants calcium uptake may be disordered by the excessive ammonium Nitrogen (Ho et al., 1993). Furthermore, the mulch can maintain the soil moisture at a moderate level to avoid the drought tolerance and prevent the weed occurrence, so that the mulch is highly recommended to be operated into the production site. According to the climate and the need of vegetation growth, the irrigation system should be managed scientifically.Selecting stress-resistant cultivars is another sensible method to solve the BER problem. Because some of the cultivars have been lost natural biodiversity during the process of domestication, the genetic variation of the wild species is quite valuable to breed modern stress-resistant cultivars in the future (Saure, 2014).ConclusionThe Blossom End Rot (BER) happens readily when the tomato plants are not able to take up sufficient calcium to support the cell growth. Although the BER is caused by the climate change pressure and the environmental conditions stress, its negative influence on Ca2+ transport and uptake may cause Ca2+ deficiency and parts of the vegetation physiological dysfunctions. Therefore, there will be an enormous loss on the tomato quality and yield. There are several effective control methods have been introduced to prevent the BER occurrence, such as scientific management practices, ABA foliar spray treatments and breed modern stress-resistant cultivars. Once the plants are infected, the accurate plant diagnosis is necessary before any measure is adopted so that the growerscan figure outtheexactcauseandappropriate treatment to reduce the loss.Reference list:Barickman, T.C., Kopsell, D.A., Sams, C., 2014. Abscisic acid increases carotenoid and chlorophyll concentrations in leaves and fruit of two tomato genotypes. J. Am. Soc. Hortic. Sci. 3, 261266.Casey Barickman, T, Kopsell, DA, & Sams, CE 2014, Foliar applications of abscisic acid decrease the incidence of blossom-end rot in tomato fruit,Scientia Horticulturae, vol. 179, pp. 356-362. DeKock et al., 1982a P.C. DeKock, A. Hall, R. Boggie, R.H.E. Inkson The effect of water stress and form of nitrogen on the incidence of blossom-end rot in tomatoes J. Sci. Food Agric., 33 (1982), pp. 509515Ho, L.C., Belda, R., Brown, M., Andrews, J., Adams, P., 1993. Uptake and transport of calcium and the possible causes of blossom-end rot in tomato. J. Exp. Bot. 44, 509518.Ohlson, EW., Foolad, MR., & Altpeter, F., 2015., Heritability of late blight resistance in tomato conferred by Solanum pimpinellifolium accession PI 224710,Plant Breeding, no. 4, p. 461.Robbins, R., 1937. Relation of nutrient salt concentration to growth of the tomato and to the incidence of blossom-end rot of the fruit Plant Physiol., 12 (1937), pp. 2150Saure, MC 2014, Why calcium deficiency is not the cause of blossom-end rot in tomato and pepper fruit - a reappraisal,Scientia Horticulturae, vol. 174, pp. 151-154. Saure, M.C., 2001. Blossom-end rot in tomato (Lycopersicon esculentum Mill.) a calcium- or a stress-related disorder? Sci. Hortic. 90, 193208.Spurr, A.R., 1959. Anatomical aspects of blossom-end rot in the tomato with special reference to calcium nutrition Hilgardia, 28 (1959), pp. 269295Suzuki, K., Shono, M., Egawa, Y., 2003. Localization of calcium in the pericarp cells of tomato fruits during the development of blossom-end rot. 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