Effect Of Interspecific Root Interactions On Cd Uptake By Intercropped Wheat And Rice

With the industral development, the problem of soil being polltued by cadmium becomes more and more serious. When crops grow together on Cd polluted soil, the effects of interspecific interactions on Cd uptake are unclear. Pot experiments were conducted in greenhouse in 2001 and 2002 to investigate the effects of interspecific below-ground interactions on Cd uptake when the extent of rhizosphere intraction between rice (Oryza sativa L.) and wheat (Triticum aestivum L.) was controlled using plastic sheet barrier, nylon mesh (30 um) barrier and without root barrier.The results of experiments showed that there were interspecific competitions between two species. Wheat growth was improved in the pots where root intermingling of wheat and rice was permitted, whereas rice growth was inhibited by the intermingling of roots, compared to without root interactions.The Cd concentration in the grain of keng rice was significantly lower in plants grown in pots with plastic sheet barrier than that in the pot where the complete root intractions were permitted (no barrier). The Cd concentration in the shoots of keng rice was 7.2 ug.g-1 in monoculture (plastic sheet barrier) and 6.7 ug.g-1 in mixed culture (without root barrier) in 2001, but 4.3 ug.g-1 in monoculture and 7.6 ug.g-1 in mixed culture in 2002 respectively. The interspecific root interactions decreased Cd concentration in the shoots and grain of wheat.The interspecific interactions had no effects on Cd distribution in rice and wheat organs. The concentration of Fe and Zn in the grain of keng rice is lower in the treatment with complete root intractions than in the treatment without root interactions. The same trend was observed in the grain of wheat.