Influence of drought stress on competition between mung bean (Vigna radiata (L.) Wilczek) and selected weed species
1996
Caelenbergh, W. van | Seynaeve, T. | Meylemans, B. | Damme, P. van (Gent Univ. (Belgium). Faculty of Agricultural and Applied Biological Sciences)
The effects of drought stress on crop-weed competition in a mung bean crop were studied in a pot experiment under greenhouse conditions in Sri Lanka. Mung bean plants and selected weed species, viz. Cyperus rotundus L., Eleusine indica (L.) Gaertn. and Synedrella nodiflora (L.) Gaertn., were grown either separately or in the combination mung bean + one weed species, and submitted to normal moisture and drought stress. Leaf Area Index (LAI), plant dry weight (DW), height of plants and root length density (RLD) were measured with a ten day interval, starting at 32 days after sowing (DAP). Besides these morphological parameters, leaf stomatal resistance (rs) was measured with a porometer. Moisture regime was the factor most significantly influencing rs as well for mung bean in all cases as for the weeds. At 32 DAP, rs was significantly influenced by the applied moisture regime in mung bean with C. rotundus. rs of S. nodiflora was high due to the combined effect of drought stress and competition. The same effect occurred at 42 DAP for mung bean grown in competition with C. rotundus and S. nodiflora. At 42 DAP, mung bean rs in the 'dry' treatment was significantly higher than that of any weed, with the exception of S. nodiflora in the 'competition' treatment. As for rs of the weeds, only S. nodiflora showed a very sharp increase in rs when grown in competition with mung bean. rs of other weeds was only influenced by moisture regime. Drought-stressed mung bean plants grew higher in competition with S. nodiflora than if grown separately. All other morphological characteristics were only influenced by moisture regime. Different morphological characteristics of all weeds were influenced by moisture regime or competition, but nowhere did interaction occur, with exception of LAI of S. nodiflora. These results would classify C. rotundus as a better competitor than mung bean under conditions of drought stress and E. indica and S. nodiflora as poor resp. very poor competitors for mung bean
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