INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY ISSN Print: 1560–8530; ISSN Online: 1814–9596 08–142/CCHS/2009/11–1–77–80 http://www.fspublishers.org Full Length Article To cite this paper: Sajjad, A., S. Saeed, W. Muhammad and M.J. Arif, 2009. Role of insects in cross-pollination and yield attributing components of Sesbania sesban. Int. J. Agric. Biol., 11: 77–80 Role of Insects in Cross-pollination and Yield Attributing Components of Sesbania sesban ASIF SAJJAD 1 , SHAFQAT SAEED, WALI MUHAMMAD AND MUHAMMAD JALAL ARIF † University College of Agriculture, Bahauddin Zakariya University, Multan, Pakistan † Department of Agri. Entomology, University of Agriculture, Faisalabad-38040, Pakistan 1 Corresponding author’s e-mail: bumblebeepak@gmail.com ABSTRACT This experiment was performed in an effort to know the pollination biology and ecology of Sesbania sesban. Different yield attributing components were measured in three types of pollination treatments i.e., wind pollination, self pollination and cross pollination by insects. Cross pollinated inflorescences produced maximum number of pods (4.41) and maximum seed weight (1.1 g) as compared to wind pollinated (2.42 pods & 0.72 g seeds inflorescence -1 ) and self pollinated inflorescences (2.25 pods & 0.46 g seeds inflorescence -1 ). Germination was also better in cross pollinated inflorescences as compared to self and wind pollinated inflorescences. Megachlie bicolor and Apis dorsata exhibited most efficient foraging behavior, whereas A. floera proved to be the most abundant pollinator with highest visitation index of 0.74. Most of the pollinator activity took place in afternoon (1530 h–1830 h). Key Words: Sesbania sesba; Pollination biology and ecology; Bee pollinators; Reproductive success INTRODUCTION Perennial Sesbania sesban is used in various agro- ecosystems around the world in a variety of ways. It can be used as fodder crop, green manure and fuel wood (Evans & Rotar, 1987; Macklin & Evans, 1990; Weigand et al., 1995) different parts are used in medicines for human and livestock (Woodward, 1988). It is native to Africa but subsequently distributed to almost every country of the world (Evans, 2001). Despite of its wide adaptation and multiple uses, little research has been done on the mating behavior, pollination biology and ecology of this species (Brewbaker, 1990; Gebermariam et al., 2002). Knowledge of pollination biology, ecology and breeding system is essential to determine genetic structure of population (Brown & Allard, 1970; Heering, 1994). Sesbania sesban was one of the five species included in the genetic improvement programme for agroforestry development in bimodal rainfall highlands of Eastren and Central Africa agro-ecological zones (Owuor & Owino, 1993). It is important to know the degree of self and cross pollination in S. sesban as it helps in developing some sampling techniques helpful for getting maximum information about genetic recombinations. Cross pollination in S. sesban takes place by a variety of bee species (Evans & Rotas, 1987). Plant species relying on animal (e.g., insects) vectors for pollination may evolve specialized flowers as a result of mutualistic interactions with certain species (Herrera, 1989). If specialized visitors are sometimes scarce or absent (e.g., Herrera, 1990; Ågren, 1996) these plant species may be at a greater risk of pollinator limitation to seed production (Jordano, 1990; Sun, 1997). Native bees are very important and specialized visitors of papilionoid flowers of S. sesban (Evans & Roter, 1987) therefore the knowledge of native bee diversity visiting on S. sesban flowers and their role in crop reproductive success is very important in order to maximize the seed yield of S. sesban. The current study aimed to provide some basic information about reproductive biology and ecology of S. sesban by finding the diversity of flower visiting bees, their relative abundance, population dynamics and ultimately their role in crop reproductive success. MATERIALS AND METHODS Study site. The study was carried out from August to November, 2007 vegetative season (August-November). The study site is located at research farm of University College of Agriculture, Bahauddin Zakariya University Multan, Pakistan (30.255º North Latitude & 071.513º East Latitude). Climate of the area is sub-tropical with hot summer and cold winter; the mean daily maximum and minimum temperatures are in the range of 38 to 50 º C and 8 to 12 º C, respectively with the mean monthly summer rainfall is ca. 18 mm. Pollinator community. Pollinator community on S. Sesban was recorded in whole flowering season. To identify the pollinator species, collection was done throughout the