Management of blood grass(isachne miliacea roth ex roem et schult) in wetland rice ecosystem (Record no. 163807)
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| 000 -LEADER | |
|---|---|
| fixed length control field | 07045nam a22001697a 4500 |
| 082 ## - DEWEY DECIMAL CLASSIFICATION NUMBER | |
| Classification number | 630 |
| Item number | REN/MA PhD |
| 100 ## - MAIN ENTRY--PERSONAL NAME | |
| Personal name | Renjan, B |
| 245 ## - TITLE STATEMENT | |
| Title | Management of blood grass(isachne miliacea roth ex roem et schult) in wetland rice ecosystem |
| 260 ## - PUBLICATION, DISTRIBUTION, ETC. (IMPRINT) | |
| Place of publication, distribution, etc | Vellayani |
| Name of publisher, distributor, etc | Department of Agronomy, College of Agriculture |
| Date of publication, distribution, etc | 2018 |
| 300 ## - PHYSICAL DESCRIPTION | |
| Extent | xiv, 263p. |
| 502 ## - DISSERTATION NOTE | |
| Dissertation note | PhD |
| 520 3# - SUMMARY, ETC. | |
| Abstract | The study entitled “Management of blood grass (Isachne miliacea Roth ex Roem et Schult) in wetland rice ecosystem” was carried out at College of Agriculture, Vellayani during the period 2016 - 2018. The objectives were to study the eco-biology and habitat affinity of blood grass, to develop an effective strategy for managing the weed, to study the influence of the management practices on weed dynamics, to work out the economics of the weed management practices and also to assess the impact of the herbicides on the soil microorganisms. The weed biology was studied by observing sample plants for a period of one year. The results revealed that blood grass which propagated through both seeds and rooted stem bits flourished in the rice field all throughout the year. The seeds showed no dormancy and could germinate soon after shedding. However direct sunlight was found essential for germination of the weed seeds. The stored seeds retained > 80 per cent viability upto six months and after that there was a sharp decline in germination percentage. Effect of water regime and soil depth on weed propagation was assessed by conducting two separate lab studies by subjecting the seeds and stem cuttings to varying soil and water depth. The design was CRD and there were 5 x5 treatments (Factor I. Water depth (W): 0, 2.5, 5.0, 7.5, 10.0 cm and Factor II. Soil depth (S): 0, 2.5, 5.0 ,7.5, 10.0 cm ) and three replications. From the results, it was inferred that soil depth was the major factor that determined the germination and establishment of blood grass which emphasized the significance of land preparation in managing blood grass. Plant and soil samples from heavily infested rice field sites in four agro ecological units (AEU 10-North central laterite; AEU 4- Kuttanad; AEU 9- South central laterite; AEU 8- Southern laterite) were collected and analysed and correlated with weed dry weight to assess the habitat affinity of the weed. The results indicated that the biomass production of blood grass has significant positive correlation with soil organic carbon and available nitrogen while EC was negatively correlated. Water level also had significant negative correlation with plant dry weight. . The field experiments to develop an effective strategy for managing the weed were conducted during the first and second crop seasons of 2016 at the State seed farm, Kottarakkara, Kerala. the initial infestation intensity of blood grass was 84 per cent. The experiment was laid out in split plot design with three replications and the crop variety used was Sreyas released from Rice Research station Moncombu, Kerala. Combinations of tillage (P) and water regimes (W) were the main plot treatments and weed management practices (M) were the subplot treatments. The tillage practices included were: P1- intensive tillage (three ploughings fb puddling) and P2 - farmers‟ practice (two ploughings fb puddling). The water regimes tried were W1-continuous deep water ponding i.e., > 7.5 cm from 7 days after transplanting (DAT) till grain filling stage, W2- >7.5 cm water from 7 DAT till panicle initiation stage and W 3- maintaining about 5cm water level with intermittent drainage (KAU, 2011). The weed management practices in the subplots were M1 - oxyflourfen @ 0.15 kg ha-1 fb one hand weeding (HW), M2 - azimsulfuron @ 35 g ha-1 , M3- (bispyribac sodium + metamifop) 70 g ha-1 , M4- fenoxaprop- p-ethyl @ 60 g ha-1 , M5- hand weeding twice at 20 and 40 DAT and M6 - unweeded control. Oxyflourfen was applied as pre- plant three days before transplanting and the post emergence herbicides were applied at 15 days after transplanting (DAT). The second crop of rice was taken immediately after the first crop without disturbing the field layout. The results of the field experiments revealed that an integrated strategy involving intensive tillage (three ploughings fb puddling), deep water ponding (ie., > 7.5 cm upto panicle initiation and saturation thereafter ) and application of azimsulfuron @ 35 g ha-1 at 3-5 leaf stage of the weed was the most efficient treatment for managing the weed in terms of weed control efficiency (WCE), crop performance and net income. Preplant application of oxyflourfen @ 0.15 kg ha-1 fb hand weeding when combined with deep water ponding and intensive tillage recorded high WCE but was inferior in terms of economics. Combinations of these modified cultural practices with manual weeding though uneconomic, was efficient in managing the weed and recorded high yield also and hence could be an option for organic rice cultivation. The results from soil seed bank studies revealed that the density of blood grass propagules in the soil could be significantly reduced through intensive tillage and continuous maintenance of > 7.5 cm water level in the field. Among the weed management practices, application of azimsulfuron recorded the lowest weed seed density in the soil. When compared to the weedy check combinations, the soil seed bank was considerably lower in all the other treatments. The response of the microbial community to varying concentrations of the herbicides included in the study was assessed by conducting a separate field experiment which was laid out in RBD with 3 replications. The treatments were : oxyflourfen @ 150, 300, 450 g ha-1, azimsulfuron 35, 70, 105 g ha-1, bispyribac sodium +metamifop @ 70 , 140, 210 g ha-1, fenoxyprop- p-ethyl @ 60, 120, 180 g ha-1 and untreated control. The results showed that the bacterial population was stimulated with each increment of the herbicide concentrations. The fungal and actinomyctes population declined significantly immediately after the herbicide application but the negative impact was only transient and in most of the treatments the population recovered within two weeks. The soil enzyme activity was also found positively influenced by the herbicide application. From the results it was concluded that an integrated strategy involving intensive tillage (three ploughings fb puddling), deep water ponding (ie., > 7.5 cm upto panicle initiation and saturation thereafter ) and application of azimsulfuron @ 35 g ha-1 at 3-5 leaf stage of the weed was very effective for managing blood grass. Similarly application of oxyflourfen, bispyribac sodium + metamifop and fenoxyprop- p-ethyl at the recommended dose did not show any negative impact on the microbial community in the wetland rice ecosystem. |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | Agronomy |
| 700 ## - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Sansamma George (Guide) |
| 856 ## - ELECTRONIC LOCATION AND ACCESS | |
| Uniform Resource Identifier | http://krishikosh.egranth.ac.in/handle/1/5810145814 |
| 942 ## - ADDED ENTRY ELEMENTS (KOHA) | |
| Source of classification or shelving scheme | |
| Item type | Theses |
| Not for loan | Collection code | Permanent location | Current location | Shelving location | Date acquired | Full call number | Barcode | Date last seen | Koha item type |
|---|---|---|---|---|---|---|---|---|---|
| Not For Loan | Reference Book | KAU Central Library, Thrissur | KAU Central Library, Thrissur | Theses | 2019-02-20 | 630 PEN/MA | 174375 | 2019-02-20 | Theses |