Please use this identifier to cite or link to this item: http://krishikosh.egranth.ac.in/handle/1/70663
Authors: REVATHI, PALLAKONDA
Advisor: SUNEETHA DEVI, K. B
Title: INTEGRATED WEED MANAGEMENT IN FORAGE LUCERNE (Medicago sativa L.)
Publisher: ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
Language: en
Type: Thesis
Series/Report no.: D8469;
Agrotags: INTEGRATED, WEED, MANAGEMENT, FORAGE, LUCERNE
Abstract: A field experiment was conducted on “Integrated weed management practices in forage Lucerne (Medicago sativa L.)” during rabi 2008-09 at Students Farm, College of Agriculture, Rajendranagar, Hyderabad. The treatments consisted of salt (10 %) treatment to seeds of lucerne + farmers practice, salt (10 %) treatment to seeds + imazethapyr @ 75 g a.i. ha-1 at 12 DAS, salt (10 %) treatment to seeds + pendimethalin @ 0.5 kg a.i. ha-1 at 12 DAS, stale seed bed + hand weeding at 30 DAS, pendimethalin @ 0.5 kg and 0.75 kg a.i. ha-1 as PE, imazethapyr @ 75 g and 100 g a.i. ha-1 at 12 DAS, pure seed of lucerne + farmers practice, farmers practice (Hand weeding at 30 DAS and after each cut), weedy check and weed free check. The experiment was laid in RBD replicated thrice. Weed flora found in different treatmental plots include Cyperus rotundus, Cynodon dactylon, Dactylactenium aegyptium, Parthenium hysterophorus, Chicorium intybus, Digera arvensis, Euphorbia hirta and Trichodesma indicum and one parasitic weed Cuscuta chinensis. The experimental results indicated that application of imazethapyr @ 100 g a.i. ha-1 at 12 DAS reduced the density of Parthenium hysterophorus but weed shift was observed towards grasses and sedges. Application of pendimethalin at higher dose (0.75 kg a.i. ha-1) was found effective than lower dose (0.5 kg a.i. ha-1) in controlling broad leaved weeds and it was not effective against grasses and sedges. Weed density and weed dry weight of weeds (excluding cuscuta) was significantly lower with weed free check and higher with weedy check treatment throughout the study period. Next to weed free check treatment, mean weed density was found significantly lower with the application of imazethapyr @ 100 g a.i. ha-1 at 12 DAS and was found on par with sowing pure seed of lucerne fb farmers practice of weed control, farmers practice alone (hand weeding at 30 DAS and after each cut), and application of pendimethalin @ 0.5 and 0.75 kg a.i. ha-1 as PE showed higher weed control efficiency over the remaining treatments. Dry weight of weeds recorded by sowing pure seed of lucerne fb farmers practice of hand weeding at 30 DAS and after each cut and application of imazethapyr @ 75 and 100 g a.i. ha-1 applied at 12 DAS was found on par with that of weed free check treatment at 30 DAS and recorded higher weed control efficiency. Application of pendimethalin @ 0.5 and 0.75 kg a.i. ha-1 as PE or in combination with salt (10 %) treatment to seeds was found less effective in reducing the dry weight of weeds over imazethapyr and registered lower weed control efficiency. Cuscuta chinensis was completely prevented by application of pendimethalin @ 0.5 and 0.75 kg a.i. ha-1 as PE or imazethapyr @ 75 and 100 g a.i. ha-1 at 12 DAS, salt (10 %) treatment to lucerne seeds + pendimethalin @ 0.5 kg a.i. ha-1 or imazethapyr @ 75 g a.i. ha-1 at 12 DAS and sowing pure seed of lucerne fb farmers practice of hand weeding at 30 DAS and after each cut. Salt (10 %) treatment to seeds + farmers practice and stale seed bed + hand weeding at 30 DAS registered lower dry weight of cuscuta and high cuscuta control efficiency than farmers practice, weedy and weed free check treatments at all the three cuts. Plant stand of lucerne recorded at 25 DAS was higher with sowing of pure seed of lucerne fb farmers practice of hand weeding at 30 DAS and afer each cut and was found on par with all other treatments, except pendimethalin @ 0.5 and 0.75 kg a.i. ha-1 applied as PE and @ 0.5 kg a.i. ha-1 applied at 12 DAS in combination with salt (10 %) treatment to lucerne seeds due to phytotoxicity effect on germination and plant stand of lucerne. Average plant height of lucerne over the three cuts was significantly higher with sowing pure seed of lucerne + farmers practice of hand weeding at 30 DAS and after each cut and was found at par with all herbicide applied treatments (T2, T3, T5, T6, T7 and T8) and salt (10 %) treatment to lucerne seeds fb farmers practice. Leaf stem ratio of lucerne was not influenced by integrated weed management practices at all the three cuts. Total green, dry and crude protein yield of lucerne (Total of 3 cuts) was significantly higher with application of imazethapyr @ 75 g a.i. ha-1 at 12 DAS and was found on par with pure seed of lucerne fb farmers practice of hand weeding at 30 DAS and after each cut, salt (10 %) treatment to seeds + imazethapyr @ 75 g a.i. ha-1 at 12 DAS. Application of pendimethalin @ 0.5 and 0.75 kg a.i. ha-1 as PE and in combination with salt (10 %) treatment to seeds applied at 12 DAS observed significantly less green, dry and crude protein yield of lucerne. Salt (10 %) treatment to lucerne seeds fb hand weeding at 30 DAS and after each cut alone recorded less total green and dry fodder yield but its combination with pendimethalin @ 0.5 kg a.i. ha-1 and imazethapyr @ 75 g a.i. ha-1 at 12 DAS increased green and dry fodder yield to an extent of 40.0 and 64.0 per cent over above treatment. Lowest green, dry and crude protein yield of lucerne was recorded with weedy check treatment and was found on par with farmers practice, stale seed bed + hand weeding at 30 DAS. Lower mean weed index was observed with imazethapyr @ 75 g a.i. ha-1 applied at 12 DAS and was closely followed by pure seed of lucerne fb hand weeding at 30 DAS after each cut, salt (10 %) treatment to seeds + imazethapyr @ 75 g a.i. ha-1 at 12 DAS and application of imazethapyr @ 100 g a.i. ha-1 at 12 DAS respectively. Residues of pendimethalin or imazethapyr were not detected in green fodder of lucerne as both the herbicides were degraded completely by the time lucerne was harvested (68 DAS). Gross, net returns and benefit cost ratio were higher with application of imazethapyr @ 75 g a.i. ha-1 at 12 DAS and was closely followed by salt (10 %) treatment to seeds + imazethapyr @ 75 g a.i. ha-1 at 12 DAS. Sowing pure seed of lucerne fb farmers practice of hand weeding at 30 DAS and after each cut gave higher gross and net returns but benefit cost ratio was less due to increased cost on hand weeding.
Issue Date: 2009
Appears in Collections:Theses

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