Int.J.Curr.Microbiol.App.Sci (2020) 9(5): 149-154 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 9 Number 5 (2020) Journal homepage: http://www.ijcmas.com Review Article https://doi.org/10.20546/ijcmas.2020.905.016 Adoption of Regular Bearing in Mango over Biennial Bearing J. S. Shivran1*, M. L. Jat2, R. K. Jat3 and Asha Jat4 1Department of Horticulture, GBPUA & T, Pantnagar, Uttarakhand- 263145, India 2Department of Horticulture, CCS HAU,Hisar, Haryana, India 3Department of Fruit Science, SDAUJagudan, Mehsana, Gujarat, India 4Department of Horticulture, Agriculture University, Jodhpur, Rajasthan, India *Corresponding author ABSTRACT The alternate bearing in mango trees as well as in other fruit species is a main concern for orchard profitability. Alternate bearing in mango appeared to be K e yw or ds related to complex relationships between vegetative and reproductive growths and it is varied according to the cultivar. Flowering is the main event that set the stage Regular bearing, for mango production each year. For the attaining the fruit flower initiation is very mango, pruning, important and it is very complex phenomena in mango. In mango trees flowering flowering is make them especially challenging for physiologists, breeders, and growers. Article Info North, east and central Indian commercial cultivars showed the biennial bearing is very serious problem, while most of the south Indian varieties bear regularly. Accepted: 05 April 2020 Biennial bearing in mango trees cause by the different factors like, C: N ratio, Available Online: hormonal balance, climatological factors etc. Therefore, different control measures 10 May 2020 for the biennial bearing are application of different chemicals, smudging, pruning etc. most widely used in view of its high potential mango production. Introduction variation in alternate years i.e. a year of optimum or heavy fruiting is followed by a The biennial bearing habit of mango year of poor or no fruiting. (Mangifera indica L.) is one of the major hurdles for its commercial cultivation for During a good year, a tree can be loaded with getting higher productivity. This cropping bumper yield; however, crop quality problem is entirely an inherent problem of the fluctuates from year to year, so that in the flowering physiology which is exclusively year following a good crop, there are different from the problems of unfruitfulness. relatively few fruits which affect the overall Biennial bearing term is synonymous to crop production (Monselise and Goldschmidt, ‘alternate bearing’ which denotes yield 1982). Irregular bearing term does not imply 149 Int.J.Curr.Microbiol.App.Sci (2020) 9(5): 149-154 variation in yield in alternate years. This term whereas in an ‘off’ year, even the shoots of imply that cropping does not follow a requisite size and maturity fail to flower. systematic pattern, i.e. an optimum crop is obtained only once in a number of years. Such Carbon / nitrogen ratio behaviour is largely due to lack of proper orchard management practices. The degree of That irregular bearing in mango was caused bienniality in the cropping of some south by nutritional deficiency, especially by Indian mango cultivars and hybrids like the nitrogen. In fruit plants, nitrogen and highest mean yield and week bienniality was carbohydrate reserves play important role in found in the cultivar Neelashan. However, flower bud initiation, even if these do not alternation is also observed at the branch form the primary cause of the phenomenon of level, emphasizing a clear branch functional biennial bearing. It is quite probable that an autonomy (Lauri et al., 1995). Souza et al., accumulation of these compounds may create (2002) observed that within a species, favourable conditions for the synthesis and alternate bearing can be more or less action of the substances responsible for pronounced depending on the cultivars in flowering. The accumulation of these mango. compounds may create a favourable condition for the synthesis and action of the substances Factors responsible for biennial bearing actually responsible for flower induction in these plants. There was an increased Several factors like, age and size of shoots, accumulation and metabolism of climatological factors, carbon/ nitrogen ratio carbohydrates, proteins and amino acids and hormonal balance have been responsible constituents in the mature plants compared for biennial bearing in mango fruit plants. with the juvenile plants (Davenport, 1997). These factors are described below as; The translocation of phosphorus is involved in controlling the alternate bearing in mango. Age and size of shoots Hormonal balance Growth in mango takes place in different flushes, which vary in different parts of the Biennial bearing problem in mango appears to country. Early initiation and cessation of be closely associated with the fruit growth, followed by a definite dormant development process and the inhibitory period, will helps the shoots to attain proper influence of the developing fruits on physiological maturity which is essential for vegetative growth. Higher levels of auxin like fruit-bud initiation. In the case of regular substances and an inhibitor (similar to ABA) bearing cultivar Rumani, December emerged and lower levels of Gibberellin (GA3) like shoots are capable of producing the flower substances are vital for a floriferous shoots in buds in the following February. However, the mango. The inverse relationship between the growth of mango shoots is purely a varietal level of endogenous inhibitor in the shoot and feature and fruit-bud differentiation in regular vegetative growth. They are also suggested bearing varieties is an annual feature. In that higher inhibitor content promotes biennial bearing varieties, it is governed by flowering in mango. Agrawal et al., (1980) ‘on’ and ‘off’ year phase of the trees rather described cytokinine-like substances isolated than by the time of origin and cessation of from stem tips of an alternate-bearing cultivar growth of shoots. In an ‘on’ year, shoots of in ‘on’ and ‘off’ years. any size or maturity differentiate flower buds 150 Int.J.Curr.Microbiol.App.Sci (2020) 9(5): 149-154 The estimated levels of gibberellins in apical main conditioning factor for ‘on’ or ‘off’ year buds for 6 months prior to the flowering in mango. The potential of shoot to form season were reported to be higher in the ‘off’ flower buds will depend on the floriferous year than in the ‘on’ year of an alternate- condition of the tree, which in turn will be bearing cultivar (Pal and Ram, 1978). determined by the amount of fruit load carried by the tree in the previous year (Singh, 1971). Climatological factors Control measures for biennial bearing in Adverse climatic conditions like rainfall, high mango humidity and low temperature sometimes convert an ‘on’ year into ‘off’ year directly or Different control measures are used for the by promoting the incidence of diseases like implying the regular bearing in mango. These powdery mildew and anthracnose. Frequent control measures are described below as; frost or low temperatures during the flowering period adversely affect the fruit set, thereby Proper upkeep and maintenance of orchards. turning an ‘on’ year into a year of low or no production crop. Chen et al., (1999) reported Deblossoming is a more severe form of fruit that the temperature is considered to be key thinning, employed to conserve the reserves environmental factor, with low temperatures of the shoots which could otherwise be (19ºC in day and 13ºC in night) favourable for depleted later on in the development of fruits. fruit bud differentiation. Deblossoming of the panicles with NAA @ 200ppm during ‘on’ year effective for the Cultural practices controlling biennial bearing in mango. Majumder et al., 1976 reported that the The earlier reports that biennial bearing alternate bearing in mango reduced by the problem is far most part a nutritional one removal axillary panicles. The partial or appears to be wrong because liberal manuring complete removal of flowers in the 'on' year and irrigation given to the 20yearsold biennial increases flowering the next year. bearing trees failed to induce regular cropping. Thus, it is evident that while Chemical regulation nutritional requirements of the fruit trees must be met for optimum performance of the trees, Ethephon has also been successful use in biennial bearing cannot be overcome by the India for increasing flower intensity of mango addition of nutrients. cultivars Langra and Dashehari during off years (Chadha and Pal, 1986). Chen, 1987 Crop load described precocious bud break and flowering of mango shoots in response to an early Generally, moderate blossoming is one of the October application of 100 ppm 6- Benzyl chief conditions of annual fruit bearing in amino purine (6-BA). The paclobutrazol fruit trees. The number of fruits retained till induced enhancement in C: N ratio has been harvest is a varietal feature. The total number reported in mango consistently higher of fruits that are harvested is important production of total sugars and reducing sugars because of their deleterious influence on the with peak availability at bud burst in apical production of new shoots and their buds (Upreti et al., 2014). Besides reducing subsequent fruit-bud differentiation. the gibberellin biosynthesis, PBZ enhances Therefore, the fruit load appears to be the the ABA content. 151 Int.J.Curr.Microbiol.App.Sci (2020) 9(5): 149-154 PBZ induced increase in