Questo studio ha avuto l'obiettivo di valutare l'influenza di differenti strategie gestionali adottate nella coltivazione del riso sull'evoluzione della flora infestante. La sperimentazione è stata condotta nel triennio 2010-2012 in appezzamento costituito da 8 parcelle di circa 2000 m2 di estensione ciascuna, presso l'azienda agricola Boschine di Vercelli. Nel corso del triennio sono state poste a confronto le seguenti gestioni colturali: AUT: aratura autunnale con interramento delle paglie, semina del riso su camera allagata (tesi di riferimento). ASC: aratura autunnale con interramento delle paglie, semina del riso su suolo asciutto, sommersione ad un mese dalla semina. BRU: bruciatura delle paglie in autunno, aratura primaverile, semina del riso su camera allagata. LIQ: aratura autunnale con interramento delle paglie e di liquame suino, semina del riso su camera allagata. PRI: aratura primaverile con interramento delle paglie, semina del riso su camera allagata ROT 1-2-3: aratura primaverile con interramento delle paglie, semina del mais o del riso. L'influenza delle differenti strategie gestionali sull'evoluzione della comunità di malerbe è stata valutata mediante l'esecuzione di rilievi effettuati sia sulla flora reale, ovvero la vegetazione infestante che si sviluppa durante la stagione colturale, sia sulla flora potenziale, ossia la vegetazione infestante che sarebbe potenzialmente in grado di svilupparsi in campo in relazione allo stock di semi presenti nel suolo. La valutazione della flora reale è stata effettuata mediante rilievi eseguiti in ciascuna parcella in aree non trattate con erbicidi (aree testimoni). Per lo studio della banca semi sono stati prelevati campioni di suolo in ogni parcella a due diverse profondità (0-10 cm e 10-20 cm). In seguito, i campioni di suolo sono stati disposti in vaschette, quindi collocati in serra in condizioni ideali alla germinazione. La determinazione della flora potenziale ha consistito nel conteggio delle specie infestanti riscontrate. L'evoluzione della comunità di malerbe nelle aree testimoni è stata valutata mediante il calcolo di specifici indici tra i quali quelli di Simpson, Shannon-Wiener e Pielou. Gli inerbimenti riscontrati nelle aree testimoni delle parcelle a riso erano prevalentemente rappresentati da Ammania coccinea, Cyperus difformis, Echinochloa crus-galli, Heteranthera reniformis, Poa spp. e Schoenoplectus mucronatus. In generale, è stata osservata una minore presenza di malerbe nella parcella liquamata con una prevalenza di Schoenoplectus mucronatus. Nelle parcelle in rotazione con il mais, sono state rilevate elevate infestazioni di Heteranthera reniformis nel 2010 e Cyperus difformis e Echinochloa crus-galli nel 2012. La semina in asciutta ha favorito lo sviluppo delle infestanti tipiche delle colture non sommerse, quali Echinochloa crus-galli, Portulaca oleracea e Poa spp. La valutazione della banca semi finale ha evidenziato densità di infestazione in generale superiori a quanto osservato nel 2009. I risultati ottenuti attraverso i rilievi sulla flora reale, potenziale ed il calcolo degli indici di diversità, hanno evidenziato che le differenti modalità di gestione possono avere una diversa influenza sulla composizione degli inerbimenti presenti nella coltura del riso.
Weeds are one of the major limiting factors in agriculture. This study aimed at evaluating the influence of different agronomic practices, adopted in rice cultivation, on the evolution of the weed community. The study was conducted in 2010-2012 in a rice field, constituted by 8 plots of 2000 m² each. During the study the following agronomic practices were compared: AUT: ploughing in autumn for incorporation of straw into the soil and rice seeding on flooded field. This plot was considered as reference. ASC: ploughing in autumn for incorporation of straw, rice seeding on dry field and flooding after 30 days; BRU: straw burning in autumn, spring ploughing and rice seeding on flooded field; LIQ: ploughing in autumn for incorporation of straw, straw burial and slurry application, rice seeding on flooded field; PRI: spring ploughing for incorporation of straw and rice seeding on flooded field; ROT 1,2,3: spring ploughing for incorporation of straw, maize or rice seeding. The influence of different agronomic practices on the evolution of the weed community was evaluated by performing assessments on both the weeds present in the fields during the cropping season and the soil seed-bank. Weed assessments were carried out on two untreated areas, randomly placed in each plot. The assessments consisted in the determination of the weed species, their density and their cover on the soil surface by using a square frames randomly placed in both untreated and treated areas. Seed bank was assessed by taking soil cores in each plot at two different depths (0-10 cm and 10-20 cm). The soil samples were placed in plastic trays and maintained in the greenhouse to promote seed germination. The emerged weed species were counted for a period of about 15 months. The evolution of weed community in the untreated areas was assessed by calculating specific indices: i.e. Simpson index, Shannon-Wiener index and Pielou index. The results of the study pointed out that the adopted agronomic practices have a different influence on the weed infestation. The most represented weeds found in untreated areas were: Ammania coccinea, Cyperus difformis, Echinochloa crus-galli, Heteranthera reniformis, Poa spp. and Schoenoplectus mucronatus. In general, the lowest weed density was observed in the plot with slurry application, with a prevalence of Schoenoplectus mucronatus. The plots in rotation with maize, recorded higher density of Heteranthera reniformis in 2010 and Cyperus difformis and Echinochloa crus-galli in 2012. Plot with rice dry seeded was characterized by species observed in non-flooded crops, such as Echinochloa crus-galli, Portulaca oleracea and Poa spp. The final seed-bank density showed generally higher values than those observed in 2009. The calculated weed indices showed an evolving weed community depending on the different agronomic practices adopted, particularly in the plots with maize rotation.
Dinamica della flora infestante in diversi sistemi gestionali risicoli
DALLA PIA CASA, GABRIELE
2013/2014
Abstract
Weeds are one of the major limiting factors in agriculture. This study aimed at evaluating the influence of different agronomic practices, adopted in rice cultivation, on the evolution of the weed community. The study was conducted in 2010-2012 in a rice field, constituted by 8 plots of 2000 m² each. During the study the following agronomic practices were compared: AUT: ploughing in autumn for incorporation of straw into the soil and rice seeding on flooded field. This plot was considered as reference. ASC: ploughing in autumn for incorporation of straw, rice seeding on dry field and flooding after 30 days; BRU: straw burning in autumn, spring ploughing and rice seeding on flooded field; LIQ: ploughing in autumn for incorporation of straw, straw burial and slurry application, rice seeding on flooded field; PRI: spring ploughing for incorporation of straw and rice seeding on flooded field; ROT 1,2,3: spring ploughing for incorporation of straw, maize or rice seeding. The influence of different agronomic practices on the evolution of the weed community was evaluated by performing assessments on both the weeds present in the fields during the cropping season and the soil seed-bank. Weed assessments were carried out on two untreated areas, randomly placed in each plot. The assessments consisted in the determination of the weed species, their density and their cover on the soil surface by using a square frames randomly placed in both untreated and treated areas. Seed bank was assessed by taking soil cores in each plot at two different depths (0-10 cm and 10-20 cm). The soil samples were placed in plastic trays and maintained in the greenhouse to promote seed germination. The emerged weed species were counted for a period of about 15 months. The evolution of weed community in the untreated areas was assessed by calculating specific indices: i.e. Simpson index, Shannon-Wiener index and Pielou index. The results of the study pointed out that the adopted agronomic practices have a different influence on the weed infestation. The most represented weeds found in untreated areas were: Ammania coccinea, Cyperus difformis, Echinochloa crus-galli, Heteranthera reniformis, Poa spp. and Schoenoplectus mucronatus. In general, the lowest weed density was observed in the plot with slurry application, with a prevalence of Schoenoplectus mucronatus. The plots in rotation with maize, recorded higher density of Heteranthera reniformis in 2010 and Cyperus difformis and Echinochloa crus-galli in 2012. Plot with rice dry seeded was characterized by species observed in non-flooded crops, such as Echinochloa crus-galli, Portulaca oleracea and Poa spp. The final seed-bank density showed generally higher values than those observed in 2009. The calculated weed indices showed an evolving weed community depending on the different agronomic practices adopted, particularly in the plots with maize rotation.| File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14240/61475