WEED MANAGEMENT STUDIES IN SYSTEM OF RICE INTENSIFICATION (SRI).

Abstract

Rice is an important crop of Pakistan. Weed infestation and traditional rice growing methods are resulting in low rice yield. System of rice intensification (SRI) has emerged as an alternative and resource efficient rice production method. Field experiments were conducted, for two consecutive years (2010 and 2011), to assess the outcome of different weed management practices and to determine critical weed competition period in rice (Oryza sativa L.) under the system of rice intensification. Experimental site was Agronomic research Area, University of Agriculture, Faisalabad, Pakistan. First experiment comprised the application of different weed control practices in SRI i.e. three times manual hoeing, three times hoeing with rotary hoe, one manual hoeing followed by foliar application of crop-water extracts, one hoeing with rotary hoe followed by crop-water extracts, post emergence application of orthosulfamuron @ 145 g a.i. ha-1, weed free and a control. Seedlings of 21 days age were transplanted in this experiment. Manual hoeing 20, 40 and 60 days after transplanting (DAT) with 5.34 and 4.99 t ha-1 kernel yield during 2010 and 2011, respectively, was recorded the best weed management method in SRI. Second experiment comprised plant spacing of 20, 25 and 30 cm and competition periods of 20, 40, 60, and 80 days after transplanting along with control and weed free treatments. In this experiment 21 days old seedlings were transplanted. The third experiment consisted of transplanting seedlings of 14, 21 and 28 days and competition periods of 20, 40, 60, and 80 days after sowing along with control and weed free treatments. The weed competition periods were randomized in sub-plots while plant spacing and seedling age were randomized in main plots in second and third experiment, respectively. All the experiments were replicated thrice. Super basmati variety was used. Nursery was raised on a soil enriched with farm yard manure and the seeds, after sowing, were covered with straw to preserve moisture and prevent the germinating seeds from heat injury and predators. One seedling per hill was transplanted in a muddy soil, and irrigation was provided in intermittent intervals as per requirements of SRI. Data pertaining to various parameters related to rice crop and weed species was recorded using the standard procedures and was analyzed using Fisher’s analysis of variance technique. Least significant difference (LSD) test at 0.05 probability was used to compare the significant treatments’ means. From the first experiment, manual hoeing 20, 40 and 60 days after transplanting (DAT) with 5.34 and 4.99 t ha-1 kernel yield during 2010 and 2011, respectively, was recorded the best weed management method in SRI. Second experiment showed that the combination of 25 × 25 cm spacing and competition for 20 DAT with kernel yield 5.4 and 5.3 t ha-1 during 2010 and 2011, respectively, was the most economical treatment combination. Moreover, experiment three ended with the finding that the combination of 21 days old seedlings and competition for 20 DAT was the most economical treatment combination in terms of kernel yield of rice i.e. 4.9 and 4.7 t ha-1 during 2010 and 2011, respectively. In short, Pakistani farmers can confidently adopt SRI to maximize their rice yield and to minimize their inputs. Minimal dependence of SRI upon synthetic chemicals can ensure environmental safety on sustainable basis.