Improving crop competitive ability using allelopathy — an example from rice

Abstract

The objective of this paper is to review the possibilities for using allelopathy to improve overall crop competitive ability against weeds, using rice, Oryza sativa, as an example. Laboratory, greenhouse and ®eld screenings for allelopathy and overall weed suppression in rice have been made and allelopathic rice germplasm has been identi®ed in laboratory and greenhouse screening. Field experiments revealed that allelopathy accounted for 34% of overall competitive ability in rice. For strongly allelopathic cultivars, allelopathy was the dominant factor determining competitive ability. Based on the results of the screenings, recombinant inbred line populations were developed for identi®cation of quantitative trait loci (QTL) controlling allelopathy. Populations of recombinant inbred lines (RILs) were derived through single-seed descent from crosses between varieties with contrasting behaviour and QTL controlling allelopathy were identi®ed. For rice and most probably also for other cereal crops, the ®ndings presented can explain the limited success in previous breeding programmes for weed competition, as allelopathy has never before been acknowledged as an important factor. The ®ndings in allelopathy indicate that it is possible to improve allelopathy in rice using marker-assisted selection. Optimizing allelopathy in combination with breeding for competitive plant types could result in crop cultivars with superior weed-suppressive ability.

Allelopathic effects of Eucalyptus citriodora on amaryllis and associated grassy weed

“…Therefore, understanding plant interactions is important to reduce the dependency on herbicide in future cropping systems. Allelopathy plays an important role in plant interaction in some plant species (Olofsdotter et al, 2002).…”

“…The results obtained with E. citriodora leaf extracts were in agreement with previous studies (Nishirnura et al, 1982;Florentine and Fox, 2003;Batish et al, 2005). In general, reduced growth of many weed species in response to different plant extracts is well reported (Rice, 1984;Olofsdotter et al, 2002, Cheema et al, 2003El-Rokiek et al, 2006). High weed growth suppression may be attributed to the presence of toxin compounds in the aqueous extracts, as reported by many authors (Barnes and Putnam, 1986;May and Ash, 1990;Shilling et al, 1992 andShiming, 2005).…”

Allelopathy as a mechanism for the invasion of Typha angustifolia

“…However, allelopathy has been extensively documented in agriculturally managed wetlands demonstrating that allelochemicals can reach phytotoxic levels in an aqueous environment (Fageria and Baligar 2003;Olofsdotter et al 2002). For example, Oryza sativa L. (rice) has been found to be allelopathic, and breeding efforts are underway to produce O. sativa varieties with enhanced allelopathic effects against common agricultural weeds (Olofsdotter et al 2002).…”

Allelopathy: driving mechanisms governing its activity in agriculture

“…These compounds are produced mainly as a result of the secondary metabolism of plants and microorganisms (bacteria, viruses and fungi) and can influence several processes in ecosystems and agroecosystems (Rizvi et al 1992;Seigler 1996;Olofsdotter et al 2002). Allelochemicals can lead to different mechanisms of action in plants.…”