Ari Rajala

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.

Chapter 4 – Improving Farming Systems in Northern European Conditions

Publisher Summary The breeding cultivars adapted to northern growing conditions and developing crop management to sustain yield potential have represented exceptional challenges for Northern Europe, compared with the global, large-scale challenges that crop production typically faces. During earlier decades, development was largely based on testing management practices and application of methods for large-scale comparative trials, in which yield response per se, economic outcome, and general applicability of the method were often sufficient for adopting a novel method or systems; crop physiology did not contribute much to these early developments. However, crop physiology will evidently play a far more important role in the future in plant breeding and developing crop management practices as climate and cropping systems change in line with the extended growing season.

Effects of applying stem-shortening plant growth regulators to leaves on root elongation by seedlings of wheat, oat and barley: mediation by ethylene

Several plant growth regulators (PGRs) commonly used in practicalfarming to restrict shoot height and control lodging were examined for theirimpact on root growth in naturally short or tall cultivars of barley (cvs.Kymppi and Saana), oat (cvs. Veli and Pal), and wheat (cvs. Mahti and Tjalve).The possible involvement of ethylene in the responses was also examined. Shootswere sprayed at the two-leaf stage with the gibberellin biosynthesis inhibitorsCycocel (chlormequat chloride) (CCC) or Moddus (Trinexapac-ethyl) (TE), or withthe ethylene-releasing agent Cerone (ethephon) (ETH) at 0, 0.1, 1, 10 or 50times the recommended agricultural rate (RR). Root elongation and ethyleneproduction by roots or shoots were unaffected by CCC at all application ratesorby TE at ×0.1 or ×1.0 RR. At ×10 and ×50 RR, TE wasinhibitory to root extension but did not increase ethylene biosynthesis bytheseroots or the shoots. ETH at ×0.1 or ×1.0 RR did not affect rootextension or ethylene production in roots or shoots. At all higher rates ofapplication ETH stimulated ethylene production strongly in shoots and roots ofall three species, while root elongation was retarded severely in barley,moderately in oat and only slightly in wheat. These differences in elongationresponse are attributed to differences in sensitivity to ethylene released byethephon. Accordingly, root elongation in wheat was only slightly affected whenethylene gas was supplied at concentrations up to 100 ppm for 3d. In contrast, root elongation in barley was strongly inhibitedbyethylene, with oat demonstrating an intermediate responsiveness.

Morpho-physiological traits characterizing environmental adaptation of Avena barbata

Seventeen morphological and physiological characteristics of three Avena barbata L. populations from Israel were measured in order to define possible combinations explaining adaptation of these populations to different precipitation, temperature and altitude regimes. Five genotypes from each A. barbata populations were collected from Ashqelon (31°63′N, low annual precipitation), En Hamifraz (32°46′N, high temperature), and Mount Carmel (32°73′N, high altitude), Israel. The behavior of the populations was followed by measuring the morpho-physiological characteristics under well-watered and moderately drought stressed conditions. The experiment was conducted at the Department of Plant Production, University of Helsinki, Finland (60°13′N). The measured traits characterized macro-morphology, transpiration rate, photosynthesis and chloroplast features. The data were subjected to principal component and discriminant analyses and the characteristic combinations that most adequately accounted for the differences among A.barbata populations were established. Differences among the populations were related to adaptation to low water availability and high altitude characterized by special light conditions. The Mount Carmel population (high water availability, high light intensities and increased proportion of UV-light) was characterized by higher tillering, hairy leaf sheaths, high transpiration, high stomatal conductance, slow fluorescence quenching capacity, and less starch granules per chloroplast when compared with populations adapted to lower altitudes. The En Hamifraz population (high mean temperature) was characterized by a high CO2 exchange rate and both En Hamifraz and Ashqelon populations (both adapted to arid conditions) used water sparingly when moderately drought stressed.

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.

Within-field variation in grain yield, yield components and quality traits of two-row barley

Recent studies of precision cereal farming systems have documented large within-field and annual variation in grain yield and quality. The principal aim of the present study was to evaluate the degree of within- and between-field variation in biomass, yield, yield component structure and quality traits, such as grain protein of two-row barley (Hordeum vulgare L.), using crop samples collected from field patches of varying yield potential. Plant samples were collected from the fields of commercial farmers located in southern Finland in 2000 and 2001. Selection of low, intermediate and high yielding patches for crop sampling was based on aerial infrared colour images taken twice during the growing season. When stands were mature, plant samples from an area of 0·5 m 2 were uprooted for yield component and quality analysis. Nitrogen accumulation prior to heading was strongly associated with biomass accumulation, indicating differences in growth potential of the different field patches. The principal yield determining trait in two-row barley was grain number/m 2 , whereas single grain weight (SGW) had a lesser effect on grain yield. The degree of variation in the quality parameters, namely protein and SGW, was not associated with grain yield. This suggests that within-field variation in yield potential does not determine heterogeneity of the grain yield in terms of grain weight or grain protein content.

Plant growth regulators to manipulate oat stands

Plant growth regulators (PGRs) are exogenously applied chemicals that alter plant metabolism, cell division, cell enlargement, growth and development by regulating plant hormones or other biological signals. For example, some PGRs regulate stem elongation by inhibiting biosynthesis of gibberellins or through releasing ethylene. PGR effects are widely studied and reported on barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.), whereas there are only a few reports addressing oat (Avena sativa L.). This is likely to be a result of smaller acreage and lower intensity of oat management and production and hence a reduced need for stem shortening by PGRs. However, this is not the case for all cereal producing regions and there exists a need to understand the potential application of PGRs to oat production. This paper represents a review of the potential of PGRs to regulate stem elongation and other biological traits governing plant stand structure and yield components, with special emphasis on oat and its responses to PGRs. Yield improvement requires more heads per unit land area, more grains per head or heavier grains. Of these yield-determining parameters, the number of head bearing tillers and grain numbers per head, compared with grain weight, are more likely to be improved by PGR application. In the absence of lodging, PGR may reduce grain yield due to potential reduction in mean grain weight and/or grain number. Cultivation systems aiming at extensive yields with intensive use of inputs likely benefit from PGR applications more often compared with low or moderate input cultivation, for which cost effectiveness of PGRs is not frequently reached.;

Hidden viability risks in the use of farm-saved small-grain seed

Agriculture must provide sustainable food security and economic development to meet future challenges; new cultivars and the use of quality seed will be key components of this. The use of farm-saved seed may increase due to imbalances between income and expenditure associated with farming. The present study characterized the quality of commonly used, and thereby easily available, farm-saved seed in Finland. Farmers provided 657 seed lot samples of spring barley ( Hordeum vulgare L.) and spring wheat ( Triticum aestivum L.) that they intended to use for sowing. Germination, seed weight, seedling elongation and within-seed-lot variability were analysed. Information was available on region, number of seed generations and cultivar. The specific aims were to identify how many generations of farm-saved seed are generally used by farmers, whether there is any safe generation threshold and the variability of quality of the seed lots. It was found that 0·80–0·84 of barley seed lots exceeded the 0·85 minimum germination requirement for certified seed, but only 0·60 of wheat. The risk of poor establishment was higher in wheat if the seed was not tested: 0·13 of wheat seed lots had germination of ⩽0·65 and 0·06 of ⩽0·50, while for barley the proportions with inadequate germination were 0·03–0·05. At most, >0·30 abnormal seedlings were recorded for barley and >0·50 for wheat. Variation in seed size and seedling length within seed lots was important, and increase in the latter was associated with reduced germination. In combination with up to 0·14 lethal fungus-infected seed, this emphasizes the need for seed upgrading measures. No safe threshold for farm-saved seed generations was determined.

Intra-plant variation for progress of cell division in developing oat grains: a preliminary study

Kauran royhy kehittyy ylhaalta alaspain, joten ensimmaisenaerilaistuva paatetahkyla on aina pisimmalle kehittynyt. Taman huomattavan royhyn sisaisen vaihtelun takia eri jyvilla on todennakoisesti hyvin erilaiset tayttymisedellytykset. Tutkimme alustavassa kokeessa kahden kauralajikkeen (Belinda ja Fiia) kukkien polyttymista eri osissa royhya ja maaritimme toistomittauksin kunkin jyvaaiheen solunjakautumisen etenemista. Havaitsimme, etta polyttyminen, solujen jakaantuminen ja maksimi solumaara vaihtelivat huomattavasti royhyn osasta toiseen. Koko royhyn polyttymiseen kului yli kymmenen vuorokautta siita, kun kehittynein royhyn paatetahkyla oli polyttynyt. Tassa jyvassa oli myos suurin solumaara. Sisajyvissa oli jarjestelmallisesti vahemman soluja kuin ulkojyvissa. Lisakokeet osoittivat, etta ulkokukan tuhoaminen ennen polyttymista lisasi sisajyvan painoa huomattavasti. Sisajyva ei kuitenkaan tassakaan tapauksessa painanut yhta paljon kuin koskemattomien kontrolliroyhyjen ulkojyvat. Sen sijaan paljasjyvaisen kauran sisajyva ei tullut painavammaksi, vaikka ulkokukka tuhottiin. Nama alustavat tulokset rohkaisevat jatkamaan tutkimuksia ja rinnastamaan havaitut erot royhyn eri osien kehittymisessa jyvan tayttymiseen, jyvan painoon seka laatuvaihteluun.

Seed quality effects on seedling emergence, plant stand establishment and grain yield in two-row barley

-1 ), hectolitre weight (HLW, kg) single grain weight (SGW, mg) and grain protein content (%) were recorded. Seed lots of CCS and FSS >2.7 mm + dis enhanced seedling emergence rate and increased the number of plants compared with other treatments. These two seed lots also produced the highest grain yield and had the lowest grain protein. Seed quality had an apparent effect on plant stand establishment and grain yield. A seed lot effect was evident despite identical targeted sowing rates that took into account germination rate and seed weight. Therefore, differences in seedling emergence and yielding capacity were likely outcomes of variation in seed vigour among the five treatments.