Optimizing Plant Population & Weed Management in Irrigated Hybrid Maize Free Essay Example

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SUMMARY AND CONCLUSION

Field experiments were conducted at farmer's field at Udumalpettai of Tiruppur district of Tamil Nadu during kharif 2014 and kharif 2015 to study the response of maize hybrid to varied plant densities and weed management practices under irrigated condition.The experiments conducted during kharif 2014 and kharif 2015 were laid out in split plot design replicated thrice with three plant spacings viz., 45 cm x 30 cm (74.074 plants per ha), 60 cm x 20 cm (83,333 plants per ha) and 60 cm x 25 cm (66,666 plants per ha) as main plot treatments and four weed control methods viz.

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, atrazine at 0.50 kg /ha as pre emergence + one hand weeding at 30 DAS, atrazine at 0.50 kg /ha as pre emergence + 2,4 " D sodium salt at 0.75 kg / ha on 30 DAS, atrazine at 0.50 kg /ha as pre emergence + twin wheel hoe weeder weeding on 30 DAS and unweeded control as subplot treatments. The overall weather conditions prevailed during the cropping period during both the years of study was normal and favourable for the growth of maize crop.

Observations on weeds such as weed density, relative density, density of dominant weeds, weed dry weight were recorded and weed control efficiency worked out. Observations on growth parameters such as plant height, leaf area index, dry matter production, physiological attributes like CGR, RGR, yield parameters viz., cob length, cob girth, number of grain rows per cob, number of grains per row, cob weight, test weight, grain yield and stover yield were recorded. In addition, days required for flowering were also recorded. The quality parameters such as crude protein and starch content were estimated.

Nutrient uptake by maize at various stages and soil available NPK were also estimated. Economic parameters such as gross return, net return and BC ratio were worked out for various treatment combinations. The important inferences from the experiment are summarized and the conclusions drawn are furnished below:6.1 Summary Weed charactersј Weed flora of the experimental field consisted of seven species of grass weeds, eight species of broad leaved weeds and one species of sedge category. The predominant grassy weeds were Cynodon dactylon and Echinocloa colonum. Trianthema portulacastrum, Amaranthus viridis and Digera arvensis were the dominant weeds among the broad leaved weeds. The only sedge present in the experimental field was Cyperus rotundus.ј Among the group of weeds, the dominant weed group was broad leaved weeds followed by grasses and sedges at all the stages during both the years of study.ј During kharif 2014, among the weeds, Trianthema portulacastrum followed by Amaranthus viridis, Cynodon dactylon, Digera arvensis and Cyperus rotundus were the dominant weeds. But, during kharif 2015, the dominant weeds were Trianthema portulacastrum followed by Cynodon dactylon, Amaranthus viridis and Cyperus rotundus. ј There existed significant difference in weed dry weight due to various spacings and weed management practices.ј With regard to spacings, 60 cm x 25 cm (S3) registered lower total weed dry weight followed by 45 cm x 30 cm. Higher dry weight of total weeds was observed with the spacing 60 cm x 20 cm at 30, 60 DAS and at harvest stages of maize crop. ј Among the weed management practices, weedy check recorded higher dry weight of total weeds compared to other treatments. Atrazine at 0.50 a.i. kg ha-1 + one hand weeding on 30 DAS recorded significantly lower total dry weight of weeds followed by atrazine at 0.50 a.i. kg ha-1 + twin wheel hoe weeder weeding at 30 DAS and both were comparable among themselves at 30, 60 DAS and at harvest stages of maize crop. ј The treatment combination of the spacing 60 cm x 25 cm along with atrazine at 0.50 a.i. kg ha-1 + one hand weeding on 30 DAS recorded higher weed control efficiency. This was followed by the spacing 60 cm x 25 cm along with atrazine at 0.50 a.i. kg ha-1 + twin wheel hoe weeding at 30 DAS and 60 cm x 25 cm along with atrazine at 0.50 a.i. kg ha-1 +2,4 D sodium salt at 30 DAS during both the years.Growth Attributes ј Plant spacing of 60 cm x 20 cm upto 60 DAS and 60 cm x 25 cm thereafter upto harvest among the plant spacings and atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine ar 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS among the weed management practices recorded taller plants. ј Plant spacing of 60 cm x 25 cm among the plant spacings and atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS, among the weed management practices recorded higher leaf area index and dry matter production. ј Among the plant spacings, the plant spacing of 60 cm x 25 cm and atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeding at 30 DAS recorded higher CGR and RGR. ј Among the plant spacings, plant spacing of 60 cm x 25 cm and atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS among the weed management practices recorded higher root length and root dry mass. Yield attributes and yieldј The yield attributes such as cob length, number of grain rows / cob, number of grains / row, cob weight and test weight were higher under the spacing 60 cm x 25 cm among the plant spacings and atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS among the weed management practices. ј With regard to plant spacings, the grain and stover yields were higher under the spacing of 60 cm x 25 cm and among the weed management practices, atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS recorded higher grain and stover yields.ј With regard to interaction effect, during both the years, the treatment combination of the spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS recorded higher grain and stover yield followed by the spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS and the spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 +2,4 D sodium salt at 30 DAS.ј Crude protein and starch content were significantly higher with the spacing of 60 cm x 25 cm among the various spacings and atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS among the weed management practices.ј Plant spacing of 60 x 25 cm among the various spacings and atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeding at 30 DAS reordered among the weed management practices recorded higher N, P and K uptake at all the stages of observation.ј The soil available nitrogen, phosphorous and potassium were higher under the plant spacing of 60 x 25 cm among the various plant spacings and among the weed management practices, atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeding at 30 DAS recorded higher nitrogen, phosphorus and potassium availability. Economicsј Gross return was higher with the spacing 60 cm — 25cm along with atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS. This was followed by the spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + one twin wheel hoe weeding on 30 DAS during both the years.ј The spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS resulted in higher net return. This was followed by the spacing 60 cm — 25cm along with atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS.ј However, with regard to B:C ratio, higher B:C ratio was recorded with the spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS followed by atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS.6.2 Conclusions The following conclusions are drawn from the results obtained in the present investigationј The plant spacing of 60 cm x 25 cm among the plant spacings and and atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS among the weed management practices recorded lesser weed density, weed dry weight and higher weed control efficiency.ј The treatment combination of the plant spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS favourably increased the growth, yield attributes and grain yield. ј The interaction effect of plant spacing and fertilizer levels had significant influence on growth and yield of maize. Higher values of growth and yield components and higher grain and stover yield were obtained at a plant spacing of 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS followed by atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS. ј The economic returns were higher with the plant spacing of 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS. However, higher B:C ratio was recorded with the spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS followed by atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS.6.3. Recommendationј Higher productivity in Kharif irrigated maize with higher economic returns could be obtained with the spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + twin wheel hoe weeder weeding at 30 DAS followed by the spacing 60 cm x 25 cm along with atrazine at 0.50 kg ha-1 + one hand weeding on 30 DAS.