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Suitability of cruciferous oilseeds as cover crops, their disease resistance and optimized cultivation technologies for improved overwintering and yield

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2024

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Kirjastaja

Estonian University of Life Sciences

Abstrakt

ABSTRACT. Cruciferous field crops are important as oil crops and inhibitors of some soil pathogens. At the same time they can be susceptible to various other diseases, as they have been intensively cultivated in short rotations. There are lot of problems with the cultivation of the main oil crop - winter rapeseed in Estonia, mostly evident through instability of seed yields. Previous studies have indicated that the cultivation of winter rapeseed as a cover crop reduces the presence of pathogen, that is causing the potato late blight; different cruciferous species have large variation in resistance to crop diseases; and the successful overwintering of winter rapeseed is related to weather conditions, sowing time and seed rates. Therefore, following hypotheses were set at the start of present research: 1) The cultivation of winter rapeseed as a cover crop has positive effect on controlling the abundance of pathogen that is causing late blight in potato, resulting in higher tuber yield; 2) The alternative cruciferous oil crops are more resistant to powdery mildew than spring rapeseed; 3) The spring rapeseed is more susceptible to Alternaria black spot disease than alternative cruciferous species; 4) The growth and development as well as the yield of winter rapeseed is dependent on the sowing time, seed rate and the sum of active temperatures during autumn growth; 5) Successful overwintering and yield potential are directly related to certain crop parameters measured in autumn. Based on the results of present thesis it was found that when cultivating winter rapeseed as a cover crop, the late blight infection emerged slightly later and there was a decrease in damaged area, but the effects on disease suppression and tuber yield were not significant. The alternative cruciferous oil crops like white mustard, ruccola/arugula and oilseed radish were not infected with powdery mildew and black spot disease, even during favourable conditions for the pathogens. Hence, these species could be used as cruciferous crops in rotations without the use of pesticides. The most suitable period for sowing winter rapeseed was in the middle of August, allowing plants to optimize their parameters for winter survival. Good indicator was the time when 7-8 true leaves had been formed, resulting in 70% survival rate and also providing higher seed yield potential.
LÜHIKOKKUVÕTE. Ristõielised põllukultuurid on olulised õlitaimed ning mullapatogeenide vähendajad. Samas on nad vastuvõtlikud erinevatele haigustele, kuna neid kasvatatakse intensiivselt lühikestes külvikordades. Talirapsi, kui põhilise ristõielise õlitaime kasvatamisega Eestis esineb probleeme, mis on seotud aastate lõikes ebastabiilse saagikusega. Erinevate teadusuuringute tulemused näitavad: et taliraps kui vahekultuur, vähendab kartuli-lehemädaniku tekitaja levikut taimikus; erinevad ristõielised kultuurid on taimehaiguste suhtes erineva resistentsusega; ning talirapsi edukas talvitumine sõltub olulisel määral ilmastikust, külviajast ning külvisenormist. Seega seati käesolevas doktoritöös järgmised hüpoteesid: 1) talirapsi kasvatamine vahekultuurina annab positiivse efekti kartuli-lehemädaniku tekitaja kontrolli all hoidmisel, mille tulemusel saagikus suureneb; 2) alternatiivsed ristõielised õlikultuurid on resistentsemad jahukaste suhtes kui suviraps; 3) suviraps on vastuvõtlikum kuivlaiksuse suhtes kui alternatiivsed ristõielised kultuurid; 4) talirapsi kasvu, arengut ja saagikust mõjutavad külviaeg, külvisenorm ning sügisel kogutud kasvuks vajalike temperatuuride summa; 5) talirapsi edukas talvitumine ja saagipotentsiaal sõltub taimede talvekindlust tagavatest tunnustest sügisel. Doktoritööst selgus, et talirapsi kasvatamisel vahekultuurina täheldati kasvuhooaja alguses küll lehemädaniku mõnevõrra hilisemat lööbimist ja kahjustuse mõningast vähenemist, kuid talirapsil vahekultuurina puudus kartuli-lehemädanikule ja ka kartuli saagikusele usaldusväärne mõju. Alternatiivsed õlikultuurid nagu valge sinep, põld-võõrkapsas ja õlirõigas ei nakatunud katseaastatel jahukaste ja kuivlaiksusega, isegi haiguste jaoks eriti soodsates tingimustes ning võiksid olla ristõieliste kultuuridena heaks valikuks, mida saab kasvatada ilma taimekaitsevahendeid kasutamata. Talirapsi sobivaimaks külviajaks osutus augusti keskpaik. Taimel moodustus kasvu peatumiseni 7–8 pärislehte ja sügisesest taimikust talvitus 70% taimedest. Samuti on sellistel taimedel kõrgem saagipotentsiaal.
Funding for this project was provided by the Estonian Research Council (Center of Excellence AgroCropFuture “Agroecology and new crops in future climates”, TK200 and PRG2503 “Development of strategies to mitigate the vulnerability of potato to pathogens under changing climate conditions in Northern Europe”) and the Estonian University of Life Sciences (base funding project P190259). Th e publication of this dissertation is supported by the Estonian University of Life Sciences.

Kirjeldus

A Thesis for applying for the degree of Doctor of Philosophy in Agriculture.
Väitekiri filosoofiadoktori kraadi taotlemiseks põllumajanduse erialal.

Märksõnad

dissertations, Green University (thesis is related to EMÜ Green University iniciative’s aims), cruciferous plants, cover crops, resistance, cultivation technology, yield

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