Pollination Requirements and Their Impact on Yield of Sikkim Mandarin (Citrus reticulata Blanco) in an agricultural field in Eastern Himalayas, India

Subhankar Gurung^1*, Arun Chettri², Aita Rani Subba (Limboo)¹, Arunika Subba¹ and Aditya Moktan Tamang³

¹Department of Botany, Sikkim Alpine University, Main Campus, Kamrang, Namchi, Sikkim, India.

²Department of Zoology, Sikkim Alpine University, Main Campus, Kamrang, Namchi, Sikkim, India.

³Department of Botany, Sikkim University, 6^th Mile, Gangtok, India

Corresponding Author E-mail:subhankar.alpineuniversity@gmail.com

Abstract:

In the face of sporadic pollinator availability, fruit crops are believed to have evolved selfing, outcrossing, apomixis, or mixed mating strategies to ensure effective reproduction. This study investigates the species’ breeding system and pollination efficiency by evaluating five pollination treatments: open pollination, cross-pollination, geitonogamous self-pollination, autogamy and apomixis. Apis cerana was found to be the most common mandarin pollinator, with a pollination efficiency of 0.5. Sikkim mandarins have partial self-incompatibility, according to field tests, with an index of self-incompatibility index (ISI) of 0.28. Fruit set varied significantly across treatments, with open pollination yielding the highest fruit set (46.00 ± 3.10%), followed by geitonogamous self-pollination (31.00 ± 6.48%), xenogamous pollination (14.00 ± 2.45%), autogamy (4.00 ± 2.29%), and apomixis (5.00 ± 2.45%). ANOVA revealed significant differences in fruit weight (F = 44.299, p < 0.001), diameter (F = 8.679, p < 0.001), and fruit seed count (F = 4.559, p < 0.01), whereas total soluble solids (TSS) and acidity showed no significant variation (p > 0.05). Autogamy generated the lowest average fruit weight (22.56 ± 2.97 g), while open pollination produced the highest (54.65 ± 2.72 g). These results underline the ecological and economic importance of pollination management in citrus plantations in the Eastern Himalayas, emphasizing the need for efficient pollinators for the best fruit set and quality.

Keywords:

Apiscerana; Eastern Himalayas; Mandarins; Pollination; Pollinators; Sikkim mandarins

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