Assessment of yield enhancement in cashew (Anacardium occidentale L.) by the pollinator sharing effect of magnetic bee-friendly plants in India Ujjwal Layek a , Krishnendu Bera b , Bubai Bera b , Sourabh Bisui b , Subir Kumar Pattanayek b , Prakash Karmakar b, ⁎ a Department of Botany, Rampurhat College, Birbhum 731224, India b Department of Botany & Forestry, Vidyasagar University, Midnapore 721102, India abstract article info Article history: Received 10 September 2019 Received in revised form 1 May 2021 Accepted 6 May 2021 Available online 11 May 2021 Keywords: Anacardium occidentale Apis dorsata Magnetic bee-friendly plant Productivity Relative pollinator service The objective of this study was to test the hypothesis that pollinator sharing among cashew (Anacardium occidentale L.) and co-blooming magnetic bee-friendly plants facilitate higher productivity of cashew nuts. We examined the reproductive efficacy of cashew in three sites with distinct vegetation pattern (site I: sparsely dis- tributed individuals, without association of co-blooming magnetic bee-friendly plant; site II: densely distributed individuals, without association of co-blooming magnetic bee-friendly plant; site III: densely distributed individ- uals, associated with co-blooming magnetic bee-friendly plants). Floral traits (including flowering time, flower architecture, number of flowers per panicle, hermaphrodite- male flower ratio, floral rewards, anthesis time and longevity of flower) does not differ among the study sites. According to the value of relative pollinator service (RPS), Apis dorsata was the primary pollinator of cashew and also shared by the co-blooming bee-friendly plants. The abundance of pollinators was the highest in site III and the lowest in site I. The nut yield was also significantly higher in site III cashew orchard which was in association with magnetic bee-friendly plants. Therefore, we can conclude that the association of co-blooming magnetic plants increased nut yield of cashew through the en- hancement of pollinator's services. © 2021 Published by Elsevier B.V. on behalf of Ecological Society of China. 1. Introduction Cashew (Anacardium occidentale L.) is a hardy drought-resistant tropical and subtropical tree, naturally distributed in tropical America across Brazil and Peru. The plant is capable to tolerate an annual precip- itation of 500–4200 mm, temperature of 21–28 °C and soil pH of 4.3–8.7 [1]. Cashew nut is a high-value export crop and used as a source of in- come by millions of rural households in the developing countries of Africa and Asia [2]. Based on the nut production statistics for the year of 2018, leading producing countries were Vietnam (2.66 million tonnes), India (0.79 million tonnes), Côte dˈIvoire, Philippines, and Benin [3]. In India, the highest nut production state was Kerala, followed by Andhara Pradesh and Maharastra. Despite the importance of cashew as a commodity crop with increasing cultivation in major producing countries, the world's average yield of cashew raw nuts is still as low as 780 kg/ha [3]. Several factors were responsible for lower yield of cashew production. Those may be due to low fruit set [4], genetically poor variety of planting material [5,6] and inadequate and irregular flowering due to adverse environmental conditions [7]. Additionally, in- adequate pollination can also causes in low productivity of cashew [8]. Therefore, dearth of flower visitors leading to pollination shortfall of cashew flowers may be an important factor for the low yield of nuts. To overcome the problem of meagre productivity, several re- searchers addressed the issue in different ways. Some of them have pro- vided information on the floral biology and pollination system of the plant [4,9–12]. Some workers like Damodaran [13], Manoj and George [14], Cavalcanti et al. [15] carried out artificial hybridization to achieve hybrid vigour with respect to nut yield, nut weight and kernel weight. Aliyu et al. [16] used exogenous plant hormones to enhance flowering precocity and increase production of hermaphrodite flowers, resulting in higher fruit set with high percentage of retention. Smith [17] sug- gested that managed honey bees may be used to enhance pollination and seed set. In this regard, Aidoo [18] conducted a study on the impact of beekeeping on cashew production. The results revealed that cashew farmers in Benin experienced a 200% increase in yield by adopting bee- keeping, compared to non adopted farmers. In major parts on India in- cluding southern West Bengal, managed beekeeping using Apis cerana Fabricius and Apis mellifera L. is less developed and much restricted re- gionally and seasonally. Therefore, the yields of most agri-horticultural crops were largely dependent on natural pollinators. Acta Ecologica Sinica 41 (2021) 243–252 ⁎ Corresponding author. https://doi.org/10.1016/j.chnaes.2021.05.003 1872-2032/© 2021 Published by Elsevier B.V. on behalf of Ecological Society of China. Contents lists available at ScienceDirect Acta Ecologica Sinica journal homepage: www.elsevier.com/locate/chnaes