Journal of Research in Weed Science

Abstract Growing two or more cultivars of same crop species in mixture reduces intra-specific competition for natural resources and increases competitive ability of crops against weed growth and thus enhances crop yield. The objective of this study was to evaluate the potentiality of growing rice cultivars in mixtures in temporal dimension for minimizing weed pressure and increasing rice yield and to determine the best time of introduction of one cultivar in relation to another cultivar. The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during aman season (July-December) 2017. Two transplanted aman rice cultivars having different plant height and growth duration viz. Binadhan-13 (tall, late- maturing and fine grained aromatic rice cultivar) and BRRI dhan49 (semi-dwarf, mid-maturing and coarse grained rice cultivar) were used in this study. The experiment comprised time of introduction of BRRI dhan49 namely 7 days before Binadhan-13, 7 days after Binadhan-13, same day as Binadhan-13, Binadhan-13 as sole crop, BRRI dhan49 as sole crop and three different weeding regime namely weedy, recommended weeding and weed free. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Both the cultivars showed better growth and higher yield when grown in mixture rather than sole culture. Transplanting of one cultivar before or after another cultivar produced more yield and suppressed weed better than transplanting of two cultivars on the same day. Thus only spatial arrangement produced no advantages over sole culture. Among the weeding regimes, weedy treatment performed the worst, while recommended weeding and weed free treatment performed similarly. Therefore, for better weed suppression and higher production, BRRI dhan49 may be transplanted 7 days before or after Binadhan-13 in 1:1 ratio following recommended weeding.

Abstract Growing two or more cultivars of the same crop species in mixture reduces intra-specific competition for growth resources by inducing variation in spatial and temporal patterns of crop growth, increases competitive ability of crops against weeds and thus enhances crop yield. This study was conducted to evaluate the potentiality of wheat cultivar mixtures to reduce weed growth and increase the wheat yield under different irrigation regimes, and determine the best row mixture ratio of two wheat cultivars for better weed suppression and higher productivity of wheat. Factors included seven cultivar mixture ratios viz. sole BARI Gom 25, sole BARI Gom 30, 1:2, 2:1, 2:3, 3:2 and 1:1 of BARI Gom 25 to BARI Gom 30, and three water management practices viz. no irrigation, one irrigation at crown root initiation (CRI) stage, and two irrigation at CRI and flowering stages arranged in a split-plot design with three replications. Results clearly indicated that cultivar mixture can improve the competitive ability of wheat plants against weeds and can increase wheat productivity. Both cultivars showed better growth, higher weed suppression and increased yield when grown in mixture irrespective of ratios compared to their monoculture. Based on the combined grain yield, different mixture ratios performed in the order 1:1, 2:3, 1:2 and 2:1 BARI Gom 25 to BARI Gom 30 under two irrigation regimes. BARI Gom 25 and BARI Gom 30 inter-planted in 1:1 row ratio under two irrigation appeared as the best practice resulting 9% and 5.83% yield advantages over sole culture of BARI Gom 25 and BARI Gom 30, respectively; while mixture ratio of 3:2 resulted in 6.43% and 3.36% weed dry matter reduction over sole culture of BARI Gom 25 and BARI Gom 30, respectively. In conclusion, cultivar mixture strategy can be adopted as an effective tool for better weed management and increased yield of wheat.