INTEGRATING CULTIVARS WITH REDUCED HERBICIDE RATES FOR WEED MANAGEMENT IN MAIZE-II
A field experiment to study the impact of integrating cultivars with reduced herbicide rates for the weed management in maize (Zea mays L) was conducted at the University of Agriculture, Peshawar Pakistan. Crop was sown during mid of June, 2007 in a triplicted randomized complete block (RCB) design with a split plot arrangement. Two local open pollinated maize cultivars (Azam and Pahari) were assigned to the main plots. The three herbicides at full recommended doses(1x) and their reduced half doses (½x) were kept into sub-plots viz; pendimethalin (Stomp 330E) @ 1.32 and 0.66 kg a.i. ha-1, s-metolachlor (Dual gold 960 EC) @ 1.44 and 0.72 kg a.i ha-1 and atrazine (Atrazine 38 SC) @ 1.57 and 0.78 kg a.i ha-1 and a weedy check. Each sub-plot measured 5.6 x 3 m2. Data were recorded on weed density (after 60 days of herbicides application and at harvesting), dry weed biomass m-2, germination %, No. of leaves and cobs plant-1, No. of kernels cob-1, cob length (cm), biological yield t ha-1 and harvest index. The data for each parameter were subjected to ANOVA technique and the significant means were subjected to LSD test for mean separation. For the main effects of cultivars, weed density at 60 days after treatment and harvesting were significant (P≤0.05), while highly significant for No. of leaves plant-1 and No. of kernels cob-1. For the remaining 6 parameters the differences for varieties were non-significant (P>0.05). For herbicides, significant differences were recorded in all parameters studied except No. of leaves plant-1 and harvest index. While for varieties x herbicides manifested non-significant differences for all the traits except germination %. Cultivar Azam alongwith s-metolachlor with full dose (1x) followed by half dose (½x) are the best herbicides for weed management in maize, while variety Pahari was evaluated as more competitive with weeds. It is thus recommended that half of the recommended dose of s-metolachlor integrated with cv. Azam may be used to harvest the economic yield of maize while keeping the environment intact.
Keywords: Weed management, pre-emergence herbicides, reduced herbicide rates, maize cultivars.