Plant Science Letters, 32 (1983) 343--348 343 Elsevier Scientific Publishers Ireland Ltd. EFFECT OF STIGMATIC EXUDATE AND PISTIL EXTRACTS OF CA JANUS CAJAN (L.) MILLSP. ON IN VITRO POLLEN GROWTH OF CYAMOPSIS TETRA GONOLOBA TAUB M.K. KANDASAMY and M. VIVEKANANDAN Department of Botany, Bharathidasan University, Tiruchirapalli-620 023 (India) (Received March 4th, 1983) (Revision received July 4th, 1983) (Accepted July 4th, 1983) SUMMARY Significant improvement of the in vitro pollen growth of Cyamopsis tetragonoloba was obtained by addition of stigmatic exudate and extracts of stigmas and styles of Cajanus ca]an to the basal medium consisting of optimal concentrations of sucrose, calcium and boron. However, addition of extracts of whole pistils and ovaries inhibited markedly both pollen germination and tube growth. Very poor germination was observed in vivo after cross pollinating the stigmas of Ca]anus with Cyarnopsis pollen. The probable causes for promotion or inhibition of pollen growth are discussed. Key words: Cyamopsis tetragonoloba -- Cajanus ca]an -- Pollen germination -- Pollen tube growth -- Stigmatic exudate INTRODUCTION Recent studies have shown that the stigmatic exudate of flowering plants is a complex mixture of proteins, sugars, phenols, lipids, free amino acids, reducing acids etc. [1--7 ]. Although the effects of individual components of the stigmatic exudate on in vitro pollen growth have been studied in a number of plants [8,9], knowledge relating to the effect of addition of stigmatic exudate as such on in vitro pollen growth is very poor [10]. Similarly, information pertaining to the physiology of pollen germirtation in vivo is also less common. Nowadays more attention is being given to wide crosses, as breeders seek more specific and general variability from genera outside the range of normally compatible taxa. Effective use of such alien variability will largely depend upon identification of incompatibility barriers between the taxa involved and development of efficient measures to overcome such barriers [11]. In the present study, growth of self-fertile 0304-4211/83/$03.00 © 1983 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland