Allelopathic pollens

Murphy, S. D. and Aarssen, L. W. (1995). Allelopathic pollen extract from Phleum pratense L (Poaceae) reduces germination, in vitro, of pollen in sympatric species. International Journal of Plant Science 156 425-434. 

Experiment 2. Effects of terpenoid allelochemicals on pollen germination The effects of the terpenoids found in many allelopathically active plants are dependent on the concentration of the active matter (Fig. 4). Linalool, cymol, citral, gaillardine and austricine excreted by many flowers, stimulated the pollen germination upto 10 7-1()" M concentrations and depress in higher ones. Rodriguez et.al (1976) described the biological effects of some sesquiterpene lactones, which are allelochemicals. 

Table 3 Effects of volatile plant excretions and water extracts (1 1000 w/v) from allelopathic species with pesticide features on the pollen Hippeastrum hybridum germination. 

Blue colour ring concentrated on plasmalemma of pollen (A). Arrows on B (lower part) shows a difference in the colour between cellular surface (blue color) and apperture for the output of pollen tube (red colour). Pistil excreted blue colour product, which covers the red coloured surface of pistil. The cholinesterase activity in plants is considered as sensitive test to study the allelopathic activity (Roshchina and Roshchina 1993 Roshchina,1999 2001a). 

While more commonly used to count or otherwise characterize cells for medical applications, Coulter Counters and flow cytometry technique can also be applied to the analysis of pollen grains in allelopathic studies. They are quite useful in determining the size and number of pollen grains. The technique is often used for assessing the production and size of pollen from the originating individual rather than how much was transferred to heterospecific stigma, as would be needed in a basic assessment of potential allelopathic interactions. 

Experiment 1. The measurement of pollen fluorescence spectra in allelopathic studies... 

Allelopathic potential of com pollen. Journal of Chemical Ecology 9 1011-1025 Luczkiewcz, M., Glod, D., Baczek, T. and Bucinski, A. (2004). LC-DAD U V and LC-MS for the analysis of isoflavones and flavones from in vitro and in vivo biomass of Genista tinctoria L. Chromatographia 60 179-185. 

Murphy, S.D. (1992). The determination of the allelopathic potential of pollen and nectar. In Modern Methods of Plant Analysis. Volume 13. Plant Toxin Analysis, H.F. Linskens and J.F. Jackson (eds), pp. 333-357. Springer-Verlag, New York,USA... 

Ortega, R.C., Anaya, A.L. and Ramos, L. (1988). Effects of allelopathic compounds of corn pollen on respiration and cell division of watermelon. Journal of Chemical Ecology 14 71-86. 

Pollen allelopathy can find utilization in field cultivations that could contain pollen of allelopathic crops or weeds. Pollen allelopathy could be an effective method for annual weed control that reproduce, at least in part, via wind pollination and flower concurrently with the allelopathic species. The effects of allelopathy should result in the loss of genetic variation and so in reduction of reproductive ability, but some plants are probably able to detoxify the pollen allelochemicals (Murphy and Aarssen 1995a, b). Murphy and Aarssen (1989) suggested possible delaying of weed flowering at later, less favorable times of the season or diurnal period, so decrease in weed pressure. However, infestation by perennial weeds can worsen due to compensation of pollen allelopathy through increase in the formation of rhizomes. 

For pollen-allelopathic breeding, plants with tall growth habit and relatively large quantity of pollen should be selected (Murphy and Aarssen 1989). Pollen of these species could be artificially dusted on the stigmatic surface of other plants. This phenomenon is yet to be studied and field tested. 

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