Effects of fertilization on growth of main upland weeds

This experiments were conducted to clarify the effects of fertilization on growth of weeds. The weeds used in this experiments were large crab-grass (Digitaria adscendens Henr.), common lamb's quarters (Chenopodium album L.), common purslane (Portulaca oleracea L.), Chufa (Cyperus microiria Steud.) and livid amaranth (Amaranthus lividus L.) which were typical upland weeds in the Kanto plain. Upland rice was used for reference. 1) Growth of fertilization plot was superior to that of non-fertilization one in plant length or main stem length, the number of tillers or branches and top dry weights at each species. The difference of growth was remarkable at the early stage of growth, and was decreased at the late stage of growth. Large crab-grass and common lamb's quarters were larger in plant length and top dry weight than upland rice of fertilization plot on and after 51-70 days after seeding at the plot of fertilization, and on and after 91 days at the plot of non-fertilization, too. 2) RGR of each species at the plot of fertilization was superior to non-fertilization plot at the period of 29-51 days after seeding, but RGR at the period of 70-91 days after seeding was reversed the results. RGR of all weeds examined at the period of 29-51 and 51-70 days after seeding was superior to upland rice at the plot of fertilization, and RGR of all weeds at the period of 51-70 and 70-91 days after seeding was superior to upland rice of fertilization plot even at the plot of non-fertilizatian. 3) The time of heading or flowering in each species delayed at the plot of non-fertilization. The delay was the most in livid amaranth, and was small in large crab-grass and common lamb's quarters. 4) The method of fertilization also affected the growth of weeds. Growth of large crab-grass, common purslane and Chufa at the inter-row was larger than that at the intra-row on the condition of band dressing, and growth at the intra-row was larger on the condition of whole layer placement of fertilizer. And especially, growth of weeds at the intra-row on the condition of whole layer placement of fertilizer was excellent. 5) From the resalts mentioned above, it was clear that weeds examined responded to fertilization sharply. The method of whole layer placement of fertilizer in summer season is unfavourable in aspect of weed cotrol. Weeds growing at inter-row are in need of early removal on the condition of band dressing.