Susanna Muurinen

Variation in harvest index of modern spring barley, oat and wheat cultivars adapted to northern growing conditions

Increased harvest index (HI) has been one of the principal factors contributing to genetic yield improvements in spring barley ( Hordeum vulgare L.), oat ( Avena sativa L.) and wheat ( Triticum aestivum L.) cultivars. Although high HI demonstrates high-yielding ability when cultivars are compared, it can also indicate challenges to yield formation when comparisons are made across differing growing conditions. The present study was designed to investigate variation in HI among modern cereal cultivars relative to that brought about by a northern environment, to assess whether HI still explains the majority of the differences in grain yield when only modern cereal cultivars are compared, and to monitor key traits contributing to HI. Stability of HI was also investigated with reference to the role of tillers. Twelve experiments (3 years, two locations, two nitrogen fertilizer regimes) were carried out in southern Finland to evaluate 12 two-row spring barley, 10 six-row barley, 10 oat and 11 wheat cultivars. In addition to HI, days to heading and maturity, length of grain filling period, grain yield, test weight and 13 traits characterizing plant stand structure were measured and analysed with principal component analysis (PCA) to detect traits associated with HI and those contributing to stability of HI. Although only modern cereals were studied, differences among cultivars were significant both in mean HI and stability of HI, and HI was associated with short plant stature in all modern cereal species. Also, single grain weight was associated with HI in all species. Differences between, but not within, species in HI were partly attributable to differences in tiller performance. Grain yield was associated closely with HI except in two-row barley. It may be possible to further increase HI of wheat, as it still was relatively low. High HI did, however, not indicate the degree of success in yield determination when environments are compared.

Germination and grain vigour of naked oat in response to grain moisture at harvest

Naked oat grain, which is free from lemma and palea, has high nutritional quality, but the unprotected grain is prone to mechanical damages caused by combine harvesting. Naked oats were grown for 3 years in southern Finland, at Viikki Experimental Farm, University of Helsinki (60° 13′N) to produce seed material for laboratory tests that evaluated: (1) genotypic differences of naked oat in sensitivity to damage during harvesting at grain moisture varying from c . 10% up to 50%, (2) the effect of mechanical damage on germination and grain vigour, and (3) grain characteristics contributing to susceptibility to reduced grain viability. In 1997, one naked (Rhiannon) and husked oat cultivar (Salo) were harvested, and in 1998–1999 additional four naked cultivars (Bullion, Lisbeth, Neon, SW 95926) were included. One large plot (14 m×10 m) was sown per cultivar. Two sowing times were used. Fully ripened grains were combine harvested on several occasions for each plot to obtain differences in grain moisture at harvest. Simultaneously, panicle samples were collected, dried and threshed by hand (controls). Grain moisture at each sampling and harvesting was monitored. About 3 months after harvesting, germination tests on blotting paper were carried out. Proportions of normally developed seedlings, seedlings lacking either radicle or hypocotyl, damaged coleoptiles, dead grains and lethally fungus-infected grains were recorded from combine harvested and hand threshed samples on different cultivars and harvest moistures. Tests on seedling elongation, seedling emergence through sand (2 cm and 5 cm depth), and ion leakage were applied to evaluate grain vigour. Groat weight, diameter, length, roundness, hardness and protrusion of embryo were determined. Our results indicated that naked cultivars were far more prone to mechanical damages than husked Salo, but differences among naked cultivars in susceptibility occurred. When targeting germination of [ges ] 75%, grain moisture at harvest should not exceed 19–26% depending on cultivar. Abnormal seedlings appeared irrespective of grain moisture at harvest, but the higher the grain moisture, more dead grains were found in harvested grains after storage. Seed vigour did not alter parallel to germination ability. High proportion of small grains in harvested yield and softer groats contributed to decreased sensitivity to mechanical damages.

Spring cereals : from dynamic ideotypes to cultivars in northern latitudes.

Ideotyypilla tarkoitetaan kasvustoa, jossa yhdistyvatkaikki tarvittavat ja hyodylliset ominaisuudet hyvalaatuisen ja korkean sadon tuottamiseksi tietyssa kasvuymparistossa. Kasvuympariston huomioiminen on erityisen tarkeata ideotyyppia hahmoteltaessa, silla ilmastolla seka edafisilla ja agronomisilla tekijoilla on keskeisin rooli kasvuston menestymisessa. Uudet viljelymenetelmat, ravinteet, satoisat lajikkeet, kastelu, kasvinsuojeluaineet seka huolellinen viljelytoimien suunnittelu ja toteutus ovat parantaneet kevatviljojen satoja niin Suomessa kuin muuallakin maailmassa. Lajikkeita on kuitenkin kehitettava edelleen erityisesti kasvinsuojeluaineiden ja typen kayton aiheuttaman ymparistokuormituksen vuoksi. Tarkastelemme tassa artikkelissa ominaisuuksia, jotka vaikuttavat keskeisesti elinvoimaisen ja hyvan kasvuston kehittymiseen ja menestymiseen ja samalla mahdollistavat panosten kayton vahentamista kasvintuotannossa. Tarkastelun kohteena ovat siten kasvuston nopea ja elinvoimainen alkukehitys, sivuversojen muodostuminen, kaapio- ja puolikaapiolajikkeet, veden- ja typenkayton tehokkuus, korsivalivarastot seka kasvuston kilpailukyky. Elinvoimainen kasvusto peittaa maan nopeasti, mika lisaa kasvuston kilpailukykya rikkakasveja vastaan ja samalla parantaa vedenkayton tehokkuutta ja saastaa maan vesivaroja. Kaapiomuotoja hyodyntamalla voidaan paitsi vahentaa lakoutumista myos tehostaa hiiliyhdisteiden jakautumista kehittyviin jyviin korsien ja juurien sijaan. Keskittamalla sivuversojen muodostuminen yhteen tai kahteen tahkalliseen tai royhylliseen sivuversoon voidaan edelleen tehostaa yhteyttamistuotteiden jakautumista seka vedenkayttoa. Erityista huomiota tulisi kiinnittaa kasvien kykyyn hyodyntaa korsivalivarastoja jyvantayttymisjakson aikana, koska saaolot ovat Suomessa usein hyvin vaihtelevat. Korsivalivarastoja hyodyntamalla jyvantayttymista voidaan jatkaa keskeytyksetta lahes saaoloista riippumatta. Kun kiinnitetaan huomiota lajikkeiden valintaan ja viljelymenetelmiin, satotasoja ja keskisatoja on mahdollista nostaa Suomessa tulevaisuudessakin.

Alterations in growth and canopy architecture among dwarf, semidwarf and tall oat lines grown under northern conditions

The Finnish growing season is particularly short, with an intensive growth period, unfavourable rainfall distribution and frequently occurring fluctuations in climate that affect crop growth and yield formation. A three-year study was conducted in the field to determine the contribution of alterations in canopy structure, tillering and stem elongation among dwarf (D), semidwarf (SD) and tall (T) oat (Avena sativa L.) lines to yield formation. Yield components, leaf characteristics and straw traits were measured from six oat lines (D lines Pal and Grane, SD lines Hja 76416 and Salo, and T lines Veli and Jalostettu maatiainen) separately on the main shoot and tillers. Results indicated that long leaf area duration and high leaf area index were associated with increased grain yield probably due to more persistent and active assimilation. Also, higher number of leaves increased the grain yield. Higher peduncle, straw and node weights associating with increased grain yield may result from more abundant assimilate reserves; however, the longer the straw and peduncle, the lower the grain yield, which may result from increased lodging of SD and T lines. The traits contributing most to the grain yield varied greatly from year to year. It is concluded that no single dominant trait determined grain yield, since yield is a product of several different traits. SD lines seemed to be most promising for further breeding programs on the basis of their growth pattern and yielding ability.