Compatibility of multinutrient mix sampoorna with herbicides for rice

Abstract

Tank mixing of agrochemicals is a common practise among farmers in order to save labour, time and application cost. However, mixing is done without having a scientific knowledge on effect of tank mixing. Tank mixing of agrochemicals may result in synergistic, antagonistic, or neutral effects on efficacies of chemicals involved. Herbicidal weed control is very common in rice as it is the economically viable and easy method. Usually post emergence herbicides are applied at 15-20 days of sowing or transplanting. There is a possibility of tank mixed spraying if the herbicides are compatible with Sampoorna. Hence a research programme entitled “Compatibility of multinutrient mix Sampoorna with herbicides for rice” was conducted during July to November 2022 to evaluate the weed control efficiency and compatibility of few post emergence herbicides with Sampoorna KAU multimix in transplanted wetland rice. Experiment consisted of thirteen treatments which included application of five herbicides at recommended rates (bispyribac sodium @ 0.03 kg/ ha, cyhalofop butyl @ 0.08 kg/ ha, 2,4-D @ 0.8 kg/ ha and premix herbicides AlmixⓇ (premix of metsulfuron methyl and chlorimuron ethyl) @ 0.004 kg/ ha and Vivaya Ⓡ (premix of cyhalofop butyl and penoxsulam) @ 0.15 kg/ ha. Respective tank mixed applications with Sampoorna KAU multimix @ 10 g/L were also included along with hand weeded plots with or without Sampoorna and unweeded check. The design was RBD replicated thrice and the variety was Uma. Spraying was given 50 days after transplanting. Phytotoxicity to crop was observed third and seventh day after spraying. Growth and yield attributes of crop were studied and weed parameters like weed count and weed dry matter production were also recorded. Phytotoxicity to rice was observed with tank mix application of 2,4- D+ Sampoorna. Brown spots on leaves and yellowing were noticed by third day itself. The symptoms reduced by 7 days after spraying as new leaves were free of toxicity. This also led to reduction in chlorophyll content at panicle initiation and heading stages. The chlorophyll content at PI stage in 2,4-D + Sampoorna was 2.94 mg/g fresh weight where s in 2,4-D alone spray it was 3.42 mg/. In all other treatments Sampoorna application resulted in slight increase in chlorophyll content. In the case of AlmixⓇ + Sampoorna though visual phytotoxicity symptoms were not present, reduction in plant height was noticed. Reduction in plant height in 2, 4-D+ Sampoorna was 17 % and 10 % at 30 and 60 days after transplanting respectively, compared to its sole application. While AlmixⓇ+ Sampoorna resulted in 13 % and 6 % reduction at 30 DAT and 60 DAT respectively. Individual application of herbicides resulted in comparable tiller counts with respect to their Sampoorna- tank mixed applications except in the case of 2, 4-D and AlmixⓇ at 60 DAT. Similar trend was noticed in number of productive tillers, grain yield and straw yield where all herbicides except 2, 4-D and AlmixⓇ registered higher values with tank mixed application with Sampoorna. Grain yield in 2,4-D+ Sampoorna was 15 percent lower than 2,4-D alone and corresponding reduction in AlmixⓇ+ Sampoorna was 8 percent. In the case of bispyribac sodium, cyhalofop butyl and premix cyhalofop+ penoxsulam, the sole application and tank mix registered comparable grain and straw yields and the grain yield ranged from 5444 to 5647 kg/ ha. Hand weeded plots registered the lowest weed dry matter at all stages. Sole application as well as tank mixed application of all herbicides were comparable in weed dry matter production and weed control efficiency. The weed dry matter in unweeded plot was 1373 kg/ ha whereas the values ranged from 150 kg/ha to 203 kg/ ha in all other treatments, indicating that tank mixing herbicides with Sampoorna has not adversely affected efficiency of herbicides. With respect to effect of Sampoorna application on grain yield of rice, the effect was not very conspicuous as the soil experimental field was not deficient with respect to micro nutrient status. The grain yields in hand weeded plots as well as well as hand weeded+ Sampoorna were comparable with grain yield of 5686 kg/ ha and 5722 kg/ ha respectively.2,4-D+ Sampoorna followed by AlmixⓇ with Sampoorna registered yield reduction of 21 percent and 14 percent compared to hand weeding+ Sampoorna spray which registered higher yield of 5722 kg/ ha. Among tank mixed combinations of herbicides and Sampoorna, 2, 4-D registered the lowest N and K uptake on tank mixing with Sampoorna followed by tank mix application of AlmixⓇ with Sampoorna. All other treatments registered comparable P uptake values except unweeded control, which was the inferior to others. It can be concluded that few post emergence herbicides for rice weed control ie; bispyribac sodium, cyhalofop butyl and VivayaⓇ (premix of cyhalofop butyl and penoxsulam) can be recommended for tank mix application with KAU Sampoorna as foliar spray at 15-20 days after sowing or transplanting. 2,4-D and AlmixⓇ are not compatible with Sampoorna and hence are not suitable for tank mix application.