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Leafy vegetables like lettuce (Lactuca sativa L.) naturally have high nitrate content and the European Commission has set maximum level for nitrate in lettuce. Glycinebetaine is an organic osmolyte alleviating plant stress, but its role in leaf nitrate accumulation remains unknown. The uptake of glycinebetaine by lettuce roots, and its potential to regulate lettuce nitrate content and improve plant quality were investigated. Two hydroponic lettuce experiments were conducted with different glycinebetaine application rates (Exp1 : 0, 1, 7.5, and 15 mM; Exp2: 0, 1 + 1 + 1, 1 + 10, and 4 mM). Plants were analyzed at varying time points. Root application resulted in glycinebetaine uptake and translocation to the leaves. Glycinebetaine concentrations > 7.5 mM reduced leaf nitrate up to 40% and increased leaf dry matter content. Glycinebetaine showed a positive effect on leaf mineral and amino acid composition. Thus, glycinebetaine could be a novel strategy to reduce the nitrate content in hydroponic lettuce.

Studies of plant adaptation to saline or dry environments have for several years recognized the role of quaternary ammonium and tertiary sulfonium compounds as nontoxic compatible solutes. One of the most studied compounds is glycinebetaine (GB), earlier known as lycine or oxyneurine. GB is a nontoxic, odorless, tasteless, and colorless amino acid derivative. Several plant species accumulate GB naturally as a response to abiotic stresses. However, many crop species are not able to synthesize GB in physiologically meaningful concentrations. On the other hand, halophytes, plants that can tolerate a high concentration of salt in the soil, are known to synthesize GB in low concentrations even when they are not experiencing any stress. GB is synthesized in chloroplasts from choline via a two-step oxidation reaction. This synthesis pathway has been the target in many attempts to either introduce or increase GB synthesis in plants by a transgenesis approach. However, in many cases the availability of choline obtained through photorespiration has restricted GB synthesis. Furthermore, availability of nitrogen can also restrict GB synthesis, since GB contains approximately 12% nitrogen. GB has so far been considered a relatively inert compound in plants. Since GB does not interact with metabolic pathways in the plant, it remains available at the cellular level for its use. Thus, it can be hypothesized that plants could be able to utilize nitrogen through GB metabolism, for example, during stress recovery. On the other hand, GB synthesis is energetically expensive for plants. Synthesis of 1 GB mole costs approximately 50 ATP moles, whereas synthesis of 1 sucrose mole costs approximately 30 ATP moles. In comparison, osmotic adjustment with inorganic ions is less costly, e.g., 1 NaCl mole equals 3.5 ATP moles. The aim of this chapter is to provide an overview of endogenous GB in plants and the transgenesis approach for introducing and improving GB synthesis in plants.

Along with the high energy-efficiency potential, light-emitting diode (LED) lighting provides the possibility for spectrum control. Our study presents the original data on the influence of LED light spectrum quality on the growth and macro- and micro-nutrient uptake of lettuce ( Lactuca sativa L. cv. Frillice) plants cultivated in indoor conditions and without daylight. Four LED light spectral combinations were investigated using conventional high-pressure sodium (HPS) lighting as a control. In general, the LED light spectra were more favourable than the HPS light spectrum for promoting the growth and nutrient uptake of plants. In particular, the light spectrum provided by the combination of the far-red, deep-red and blue LEDs had the highest growth and nutrient uptake indices. This spectral combination particularly enhanced the uptake of potassium, calcium and magnesium in comparison to control plants grown under conventional HPS lamps. The uptake of iron and zinc were significantly influenced by the spectral changes of the red and blue light.

Sphagnum mosses are globally important owing to their considerable peat-forming ability and their potential impact on global climatic cycles acting as a long-term net carbon sink. However, changes in climatic conditions due to global warming may affect the relations between Sphagnum mosses and vascular plants but also the competition among Sphagnum, and thus alter the accumulation of carbon on boreal wetlands. Sphagnum mosses are a plant genus with a favorable ability to grow in low solar irradiance and temperature conditions compared to vascular plants. This may be increasingly beneficial in increased wintertime temperatures and predated snowmelt conditions. To understand particularly the importance of early spring photosynthetic activity and thus the role of the length of growing season on carbon balance, we analyzed the CO2 exchange of Sphagnum mosses with closed chamber technique in two categories of microtopographical habitats, hummocks and lawns, during four seasons 2010-2013 on a raised bog in Central Finland. During CO2 exchange measurements, instantaneous net ecosystem exchange (NEE) and ecosystem respiration (RE) were measured. Our results show that the mean measured seasonal NEE, i.e. the instantaneous net carbon sequestration, of hummocks was generally only slightly higher than the NEE of lawns, but the mean measured seasonal RE of hummocks was clearly and significantly higher than the RE of lawns in every study year. A reason for the observed still higher seasonal carbon sequestration of hummocks than that of lawns besides the slightly higher rate of carbon accumulation was the longer duration of physiologically active growing season. Therefore, hummock-forming Sphagnum mosses exposed firstly from snow cover showed to get the extra time for photosynthesis and thus extra benefit compared to other mire plants. This may be further enhanced by the expansion of hummock-forming Sphagnum moss dominated raised bogs towards northern aapa-mire region due to the global warming.

In Nordic countries during the winter months supplemental lighting is essential for year-round cucumber production. In this research the effects of full HPS (top and interlights) illumination is compared to hybrid (HPS top, LED interlights) and full LED (top and interlights). The results showed that fruit yield was highest in the HPS-LED treatment whereas the electrical use efficiency (kg yield J-1) increased when HPS was replaced with LED. In LED-LED the light use efficiency (g fruit FW mol-1 PAR) was highest but resulted in a fewer number of fruits in mid-winter particularly and the lowest yield potential. The lower temperature and lower light level due to LED-LED lighting lead to reduced photosynthesis capacity, flower initiation rate and water use efficiency whereas increased stem elongation and leaf expansion compared to other treatments. Differences in light quality of LED and HPS are also discussed in terms of cucumber yield formation.

Effects of supplemental lighting, semi-closed greenhouse and split-root fertigation on weekly to seasonal heat and electricity use and CO2 emissions in cucumber growing were estimated in Finland. With moderate lighting (170 W m-2 above rows, 60 W m-2 inter-row) in a ventilated greenhouse, seasonal electricity and heat use (MJ kg-1 cucumber) were 20–50 and 10–25, 17–30 and 3–8, 38–55 and 10–18 in spring, summer and autumn to mid-winter, respectively. In summer, a semi-closed greenhouse improved energy use efficiency by 20–30% and split-root fertigation by 0–15%. Raising light intensity and applying inter- row lighting allowed higher yields in autumn to mid-winter without affecting electricity use efficiency. In other seasons, increasing the lighting decreased the efficiency. The emissions largely resulted from electricity use. Direct emissions (kg CO2-eq kg-1) based on propane and electricity from the national grid were 2.5, 1.5 and 3.3 in spring, summer and autumn to mid-winter, respectively. Efficiency of using solar and supplemental PAR was markedly lower in summer than in other seasons. The results provide profile of energy use and emissions and point to ways to reduce them.

Luonnonvalotuotannossa voidaan säästää 30 – 50 % lämmityksestä kaksinkertaisella katteella ja lämpöverhoilla. Merkittäviä säästöjä odotetaan myös koristekasvien vuorokautisen lämpötilasäädön syklin muuttamisesta. Tämä ei vaadi investointeja, jos säätöjärjestelmä on nykyaikainen. Ympärivuotisen valotetun vihannestuotannon energian kulutus on alempi tuotettua kiloa kohti kuin valottamattoman, johtuen valon vaikutuksesta kasvuun. Kurkun tuotannossa välitön CO2-päästö on 0 – 2.3 kg per tuotettu kg. Valotetun tuotannon vuosisatoa voidaan edelleen nostaa 10 – 15 % jäähdytyksellä. Päästöt vähentyvät vastaavasti. Simuloinnin mukaan yhdistämällä jäähdytys, paremmat kasvualustat, tarkempi säätö ja LED-valotuksen odotettu kehitys energian kulutus voisi alentua 30 – 50 % nykytuotantoon verrattuna. Jos lämmitys toteutetaan uusiutuvalla energialla, mutta sähkö edelleen nykyisellä tuotantorakenteella, välitön CO2-päästö kurkkutuotannosta alentuisi tasolle 1 – 1.2 kg per tuotekilo. Paikallista ja kansallista sähkön tuotannon rakennetta muuttamalla voidaan kasvihuonetuotannon CO2-päästöjä alentaa tästä edelleen. Markkinasähkön päästöjen alentuminen 10 prosentilla alentaa 9 % kurkun tuotannon päästöjä. Uusiutuvalla energialla tuotettua sähköä käyttämällä suoraan tuotannosta aiheutuvat päästöt painuisivat lähes nollaan. Jäähdytyksellä varustetusta yhden hehtaarin huoneesta voitaisiin saada nykyään ulos keväästä syksyyn 5 – 6 GWh 15 – 20-asteisena vetenä, jolla on alhainen myyntiarvo, mutta sillä voi olla arvo paikallistaloudessa.

There is an urgent need to find environmentally sustainable technologies that help to address the challenges related to increasing global demand for energy and food. Horticultural lighting allows for year-round cultivation of vegetable crops independent of weather conditions or season of the year. However, high energy prices, environmental impact and market competition are threatening this industry. Although understanding the principles and processes behind human responses to light and lighting is important, the investigation of similar aspects for plants deserves more attention from the lighting research community. This paper provides an overview of the present and future challenges facing horticultural lighting and food production in the context of a food- and fuel-hungry world.

We investigated the hypothesis that split root fertigation (SRF) approach could provide complementary benefits over traditional fertigation (TF) in terms of water use, vegetative growth and yield formation in the high radiation season and under two atmospheric conditions in a greenhouse. Plants of cucumber (Cucumis sativus L. cv. Cumuli) were grown in a traditional high-wire cultivation system in a peat growing medium. In the SRF method the root system of a plant was separated into two compartments over the crop cycle. One compartment received fertigation solution with low EC (1.2 dS m−1) and the other compartment solution with high EC (3.5 dS m−1) value. In the TF method the EC value of fertigation solution was 2.4 dS m−1. The atmospheric conditions included an open (ventilated) and a semi-closed (cooled) greenhouse. The employment of cooling resulted in an enhancement of the average CO2 in a semi-closed (810 ppm) over an open (530 ppm) greenhouse resulting in a yield improvement (37%). SRF improved water uptake in both atmospheric conditions and water use efficiency (WUE) in an open greenhouse. The water uptake in SRF was highest in the root part with the low EC values, namely 61% in the open and 66% in the semi-closed greenhouse. In both atmospheric conditions, SRF decreased flower abortion, leading to an improved fruit set with a small effect on vegetative growth. SRF increased yield by 21% in the open and 17% in the semi-closed greenhouse compared to TF in corresponding greenhouses.

Jakojuuriviljelyssä kasviyksilön juuristo jaetaan eri lohkoihin. Tällöin kullekin juuristo-osuudelle voidaan antaa vaihteleva määrä vettä ja ravinteita. Kasvihuonetuotannossa rajoitetun kasvualustan käyttö tarjoaa hallitun mahdollisuuden jakojuuriviljelytekniikan soveltamiseksi. Tehokkaassa kasvihuonetuotannossa ravinteet ja vesi annetaan samassa liuoksessa, mutta näiden kasvutekijöiden saatavuutta kasvit säätelevät kuitenkin eri fysiologisten mekanismien avulla. Siten on mahdollista, että nykyinen homogeeninen kasvualustaravinneliuosyhdistelmä ei ole kaikkein optimaalisin sadontuoton kannalta. MTT:n kasvihuonetutkimuksessa selvitettiin, miten kahteen juuristo-ositukseen perustuva jakojuuriviljelytekniikka vaikuttaa kurkun sadonmuodostukseen ja vedenkäyttöön kahdessa erilaisessa kasvihuoneen ilmastoympäristössä. Jakojuuriviljelyssä toisen osion kasteluravinneliuoksen johtokyky oli 1,2 dSm-1 ja toisen 3,5 dSm-1. Yhtenäisjuuriviljelyssä liuoksen johtokyky oli 2,4 dSm-1. Tulokset osoittivat, että jakojuuriviljelyn avulla voidaan kurkun satoa lisätä jopa 20 % perinteiseen yhtenäisjuuriviljelyyn verrattuna. Sadonlisäys oli samansuuruinen sekä tuuletetussa että jäähdytetyssä kasvihuoneessa. Vertailtaessa yhtenäisjuuriviljelyn kurkun satoa tuuletetussa kasvihuoneessa (19,7 + 0,7 kgm-2) ja jakojuuriviljelyn satoa jäähdytetyssä kasvihuoneessa (32,4 + 1,0 kgm-2 ), oli satoetu merkittävä. Sekä tuuletetussa että jäähdytetyssä kasvihuoneessa jakojuuriviljely vähensi hedelmien abortoitumista, jolloin jakojuuriviljeltyyn kurkkuun kehittyi noin 18 % enemmän kauppakelpoisia hedelmiä. Jakojuuriviljely edisti kurkun vedenottoa. Kurkkusadon laatu ja varastointikestävyys olivat riippumattomia viljelytekniikasta. Tulokset osoittivat, että jakojuuriviljely tehostaa kasvihuonetuotannon resurssien käyttöä ja jatkotutkimuksessa selvitetään menetelmän soveltuvuutta kasvihuonetomaatin ja –paprikan viljelyssä.

Tällä hetkellä nurmirehuihin perustuvalla kotieläintuotannolla on hyvät taloudelliset kilpailuedellytykset, sillä nurmisato Suomessa on lähellä Keski­Euroopan satotasoa. Nurmilohkot joudutaan kuitenkin uusi­maan 3­5 vuoden välein. Tämä onkin merkittävä osa sen tuotantokustannuksista. Täydellisen uusimisen sijasta voidaan nurmen elinkaarta ja satoa lisätä täydennyskylvöllä. Parhaiten täydennyskylvöön soveltu­vat lajit ja lajikkeet, joiden alkukehitys on nopea. Täydennyskylvetyn nurmikasvin kilpailukykyvyn kan­nalta on tärkeää, että kasvi saa heti itämisen jälkeen siemenen ulkopuolisia ravinteita. Aikaisempien tut­kimusten mukaan ravinteiden saantia voidaan edistää siemenen ravinnepinnoituksella. Kemira GrowHow Oyj–yrityksen tuotteisiin kuuluvat iSeed® pinnoitetut siemenet. Uutena iSeed®­sovelluskohteena ovat nurmikasvit. Tämän tutkimuksen keskeisenä tavoitteena oli selvittää, voidaanko nurmikasvien alkukehitystä ja sadontuottoa parantaa täydennyskylvöllä ja erityisesti käyttämällä ravinne­pinnoitettuja raiheinän ja timotei­nurminadan siemenseoksia. Kokeet tehtiin sekä kasvihuoneessa että kenttäkokein pellolla vuonna 2005. Tutkimuksen astia­ ja kenttäkoetulokset osoittivat, että nurmikasvien siemenen ravinnepinnoitus edistää kasvin kasvua ja tehostaa täydennyskylvöstä saatavaa satoetua. Astiakokeissa kasvin nopean alkukehityk­sen kannalta parhaimmaksi ravinnepinnoitteeksi osoittautui metyleeniurean (MU) ja monoammoniumfos­faatin (MAP) yhdistelmä. Pinnoitus paransi ravinteiden, erityisesti typen ja fosforin ottoa jo orastumisvai­heessa, mikä oli osittain seurausta juuriston suuremmasta tiheydestä heti itämisen jälkeen. Maan ravintei­suudesta riippumatta kasvin korkeampi ravinnepitoisuus yhdessä tiheämmän juuriston kanssa johti myös parempaan jälkikasvuun. Ravinnepinnoitetulla siemenellä kylvetyssä kasvustossa oli parempi sadontuottokyky erityisesti toisen kasvujakson aikana pinnoittamattomaan siemeneen verrattuna. Siten siemenen ravinnepinnoitus vahvistaa oraiden kilpailukykyä ja jälkikasvua täydennyskylvetyssä vanhassa nurmessa. Astiakokeisiin perustuen maan ravinnepitoisuuden kohottaminen ei heikennä pinnoitetusta siemenestä saatavaa kasvuetua. Näin ollen pellolla käytetty suositeltu lannoitus edistänee myös iSeed­siemenestä kehittyneen kasvuston sa­donmuodostusta. Tämän tutkimuksen vaihtelevissa lannoitus­ ja maan ravinneoloissa suoritetut kenttäko­keet tukevat aikaisempia tutkimuksia, joiden mukaan ravinnepinnoitetun nurmisiemenen käyttö on sa­toedun saavuttamisen suhteen todennäköisempää kuin pinnoittamattoman siemenen käyttö.

The effects of glycine betaine dip, packaging method, and storage time on the sensory quality of shredded Iceberg lettuce were first modeled using a statistical experimental design, followed by a second storage test verifying the effect of the glycine betaine treatment. Shredded lettuce was dipped in 0 to 100 mg/liter active chlorine solution and then in 0 to 1.0 mol/liter glycine betaine solution, packed in 25 μm oriented polypropylene film, 250 g per package, and stored at 5°C for 8 days. Models with good predictability were created suggesting that the glycine betaine dip helped retain sensory quality, especially appearance (P < 0.05). The models also suggested that washing periods over 60 s were not needed and that the microperforation of packages should not exceed 0.31 mm2 per package. The modeled positive effect on sensory quality was verified in the second storage test (P < 0.05). The optimum glycine betaine concentration was 0.2 mol/liter. Chlorination of the first dip particularly retained appearance of packed lettuce.

Glycinebetaine, a novel product from sugar beet (Beta vulgaris L. v. altissima), is purified from molasses during sugar processing through chromatographic separation, enrichment and crystallisation. Glycinebetaine is environmentally safe, non-toxic and water-soluble and is found in animal, microbe and plant cells. Most halophytes, when grown under stress, synthesise glycinebetaine in their chloroplasts and accumulate it as an osmoprotectant. Here we show that foliarly applied glycinebetaine offers a new possibility to stabilise crop production under field conditions: fruit yield of tomato plants (Lycopersicon esculentum Mill.) grown in saline soils or exposed to high temperatures in California increased up to 39% when glycinebetaine was applied during midflowering. Similarly, glycinebetaine treatment of tomato plants in a commercial vegetable producer's greenhouse in Southern Finland increased the yield and the number of tomato fruits. In a separate greenhouse experiment, we showed that glycinebetaine application increased the rate of net photosynthesis of adequately watered and salt stressed tomato plants.

It has been reported that foliar application of glycinebetaine reduces the effect of abiotic stresses on crops, including tobacco (Nicotiana tabacum L.), soybean [Glycine max (L.) Merr.], and maize (Zea mays L.), especially during the recovery period. The aims of this study were to determine the effect of foliar application of glycinebetaine on biomass accumulation and photosynthetic capacity of turnip rape (Brassica rapa L. ssp. oleifera) and pea (Pisum sativum L.). Experiments were carried out in a greenhouse and in the field, and records were taken on differentiation and emergence of floral organs. Biomass accumulation, relative growth rate (RGR), specific leaf area, leaf chlorophyll content, and nitrogen uptake were also measured for pea. In the experiment in the greenhouse, glycinebetaine application increased relative growth rate of both crops, especially when drought‐stressed and when recovering from drought. Application of 0.20 M glycinebetaine increased RGR of pea, recovering from drought, by 13%...

Various soybean cultivars were grown under different watering regimes in the field and greenhouse in south-eastern U.S.A. (1995 and 1996), and in the field in north-eastern Western Australia (1995). Aqueous glycinebetaine was applied at different growth stages onto their foliage with the objective of ameliorating effects of water stress on photosynthesis activity, nitrogen fixation, leaf growth, biomass accumulation and seed yield. There were cultivar differences in response to drought. Trends which suggest that exogenous glycinebetaine could improve photosynthesis activity, nitrogen fixation and leaf area development, were established. The observed seed yield increase of both well-watered and drought-stressed plants was associated with greater number of seeds following the application of 3 kg ha−1 glycinebetaine. The results indicate that foliar-applied glycinebetaine possesses anti-transpirant properties and has the potential to improve drought tolerance and reduce the amount of water used for irrigation, without any significant decrease in economic yield. There is evidence that soybean could be classified as a low-accumulator of glycinebetaine.

A single foliar spray with 2.5 mM glycinebetaine (GB) was applied on potato (Solatium tuberosum L.) cvs. Matilda, Sabina and Saturna grown in a sand bed infested with Streplomyces scabies (Thaxter) Waksman & Henrici at tuber initiation. A period of drought was maintained after GB treatment to enhance scab infection. Logit models were used to compare scab incidence in all harvested tubers (n = 622) and the type of scab in the symptomatic tubers (n = 382), whereas the tuber surface areas covered with scab lesions were compared using ANOVA. A 10 g increase in tuber weight increased the odds of scab incidence by 11.3%. Scab incidence was lowest in Sabina and highest in Matilda. Raised scab and superficial scab were common in all cultivars, but pitted scab developed only in a few tubers of Sabina and Matilda. Among the scabby tubers, the incidence of raised scab was highest in Sabina and lowest in Saturna. The mean surface area covered with scab was 32.8% in Matilda, 11.7% in Saturna and 7.5% in Sabina. Treatment with GB slightly reduced the severity of scab symptoms, as shown by the reduction in the proportion of tubers with raised scab among the scabby tubers (odds 0.60). No effect on the incidence of scab or the tuber area covered with scab lesions was detected following GB treatment., Perunaruven torjunta viljelyteknisin menetelmin on ongelmallista. Perunan fysiologiaan vaikuttavien ja ruven syntyä estävien kemiallisten aineiden kehittäminen tehostaisi ruven torjuntaa. Tässä tutkimuksessa perunarupea aiheuttavalla sädebakteerilla (Streptomyces scabies) saastutettuun hiekkapetiin istutettujen perunoiden (Matilda, Sabina ja Saturna) lehvästö ruiskutettiin glysiinibetaiinilla mukulanmuodostuksen alkaessa. Kontrolli ruiskutettiin tislatulla vedellä. Käsittelyn jälkeen kasvualustan annettiin olla jonkin aikaa normaalia kuivempana rupi-infektion edistämiseksi. Rupisten mukuloiden ja eri rupityyppien osuuksia sekä ruven peittämän pinta-alan eroja verrattiin. Riippumatta käsittelystä ja lajikkeesta, mukulan koon kasvaessa ruven esiintymisen todennäköisyys kasvoi. Rupisten mukuloiden osuus oli suurin Matildassa ja pienin Sabinassa. Myös ruven peittämä mukulan pinta-ala oli suurin Matildassa ja pienin Sabinassa. Laakarupi ja kohorupi olivat yleisiä kaikissa lajikkeissa, mutta syvärupea oli vain muutamissa Sabinan ja Matildan mukuloissa. Kohorupea oli eniten Sabinassa ja vähiten Saturnassa. Glysiinibetaiinikäsittely vähensi lievästi rupioireiden ankaruutta kaikissa lajikkeissa, mikä ilmeni kohorupisten mukuloiden osuuden vähenemisenä, mutta rupisten mukuloiden osuuteen ja ruven peittämään mukulan pinta-alaan sillä ei havaittu olevan vaikutusta.

Competition and yield advantage in barley varietal mixtures and in barley-oats mixtures were investigated. The trials were based on replacement series, but in a few cases the overall density of the stand was varied on the basis of an addition series. Both models of competition, one based on the de Wit model and the other upon a linear regression model, agreed as to which component was the dominant and which was the subordinate in the mixture. The competition coefficients from regression analyses depicted competition between components better in a dense than in a sparse stand. The competitive ability of a genotype did not depend directly upon individual characters of the genotype, such as rate of initial development, earliness, culm height, tillering capacity or grain yield in monoculture (adaptation), A good combination of characters from the viewpoint of competition was provided by the barley cv. Arra with its rapid initial development and rapid culm growth (earliness), the variety being dominant irrespective of number of components in the mixture, stand density, level of nitrogen fertilization or growing season. This suggests that competitive relations and distribution of resources within a mixture are determined at an early stage in the growing period. In other cases the competitive ability of a genotype varied from one environment to another with the competitive relations between components being inconsistent. The dominance of an aggressor usually increased with increasing nitrogen fertilization especially when the total density of the stand was high. As a rule, competition affected all the components of yield with the kernel weight being least affected. The grain yield of varietal mixtures did not differ from the yield of the highest yielding component grown alone, i.e., mixtures did not over yield. The relative yield total of varietal mixtures was higher at low (RYT > 1) than at optimal densities (RYT =1). Also the relative yield total was higher under conditions where the nitrogen fertilization was not optimal. The results of a varietal trial repeated during three successive years indicated that the relative yield total of a given mixture varied from one growing season to another, fluctuating around unity. Thus highly adapted barley varieties appear to compete for the same resources, and the grain yield advantage of such mixtures is marginal. The results of the barley-oats mixture trials revealed that the mixture may over yield. The relative yield totals of barley-oats mixtures were usually equal to or greater than unity the latter suggesting that the mixtures of barley and oats may use resources more efficiently than monocultures, and some grain yield advantage could be achieved with such mixtures. The protein yield of the barley-oats mixtures did not differ from the yield of the highest yielding component grown alone. The ratio of actual and expected protein yield and the relative protein yield total were usually slightly greater than one. The grain yields of mixtures were not consistently more stable than monocultures as determined by the coefficient of variation., Kenttäkokein tutkittiin ohran lajikeseoksissa ja ohran ja kauran lajiseoksissa tapahtuvaa kilpailua ja seosten sadontuottoa. Kokeet perustuivat korvaussarjakoemalliin. Seosten komponentit olivat virallisia lajikkeita. Sekä de Wit-malli että regressioanalyysiin perustuva kilpailuinani osoittivat komponenttien valtaavuussuhteet samansuuntaisesti. Regressioanalyysi kuvasi kilpailua erityisesti tiheissä kasvustoissa. Lajikkeen kilpailukyky ei ollut yksiselitteisesti riippuvainen lajikkeen yhdestä ominaisuudesta kuten esimerkiksi alkukehityksen nopeudesta, aikaisuudesta, korren pituudesta tai puhdaskasvustosadon määrästä. Ohralajikkeista Arran nopea alkukehitys ja aikaisuus oli hyvä yhdistelmä kilpailukyvyn kannalta lajikkeen ollessa aina vallitseva. Arran vallitsevuus oli riippumaton seoksen komponenttien lukumäärästä, seoksen kylvötiheydestä, typpilannoituksen määrästä ja kasvukaudesta. Muiden lajikkeiden kilpailukyky vaihteli ympäristöstä toiseen komponenttien kilpailusuhteiden ollessa vaihtelevia. Yleensä vallitsevan lajikkeen vallitsevuus lisääntyi kasvuston typpilannoituksen lisääntyessä, kun kasvuston kylvötiheys oli suuri. Kilpailu vaikutti kaikkiin satokomponentteihin kilpailuvaikutuksen kohdistuessa vähiten jyvän painoon. Lajikeseosten jyväsato ei ollut tilastollisesti merkitsevästi suurempi kuin eniten puhdaskasvustonatuottaneen komponentin jyväsato. Lajikeseosten suhteellinen kokonaissato oli suurempi harvassa (RYT> 1) kuin kasvutiheyden suhteen optimaalisessa kasvustossa (RYT =1). Lajikeseosten suhteellinen kokonaissato oli suurempi kasvustossa, jonka typpilannoituksen määrä ei ollut optimaalinen. Kolmena peräkkäisenä kasvukautena toistettujen lajikeseosten suhteellinen kokonaissato oli lähellä yhtä. Siten tulokset osoittivat, että hyvin sopeutuneet ohralajikkeet kilpailevat samoista kasvutekijöistä ja seosten satoetu jyväsadonmäärän suhteen on marginaalinen. Ohran ja kauran lajiseosten jyväsato oli joissakin tapauksissa tilastollisesti merkitsevästi suurempi kuin eniten puhdaskasvustonatuottaneen komponentin jyväsato. Lajiseosten suhteellinen kokonaissato oli yleensä yhtä suuri tai suurempi kuin yksi jälkimmäisen tapauksen osoittaessa, että seokset saattavat hyödyntää kasvutekijöitä paremmin kuin vastaavat puhdaskasvustot ja seosten käyttö saattaa olla perusteltua. Lajiseoksen valkuaissato ei poikennut tilastollisesti merkitsevästi eniten puhdaskasvustonatuottaneenkomponentin sadosta. Suhteellinen kokonaissato valkuaissadon suhteen oli tavallisesti suurempi kuin yksi. Seokset eivät olleet yksiselitteisesti jyväsadon määrän suhteen vakaampia sadontuottajia kuin puhdaskasvustot vaihtelukertoimella mitattuna.

The characteristics and performance of a modified stairstep, nutrient solution recycling, apparatus are described. An experiment in which the allelopathic potential of Agropyron repens was examined showed the apparatus to be reliable and accurate in operation. Allelopathic activity by A. repens was confirmed. The apparatus is also suited to studies of phytochemicals produced in stubble retention reduced tillage systems, in green manuring and in cognate areas.

Glycinebetaine is known as an osmoprotectant which is accumulated in certain plant species under salt and drought stresses. Exogenous applications of glycinebetaine on crop plants unable to synthesise glycinebetaine is a possible approach to overcome the environmental limitations of crop production. Information about the capability of plants to take up and translocate foliar-applied glycinebetaine is, however, limited. In this study, glycinebetaine solution, with and without surfactants, was exogenously applied to foliage of summer turnip rape (Brassica rapa L. ssp. oleifera), soybean [Glycine max (L.) Merr.], pea (Pisum sativum L.), tomato (Lycopersicon esculentum Mill.), and spring wheat (Triticum aestivum L.) in greenhouse experiments. Uptake of glycinebetaine was monitored using high-performance liquid chromatography. [14C]glycinebetaine was applied to leaves of turnip rape plants and translocation to other plant organs was monitored autoradiographically. [14C]glycinebetaine was translocated to roots within two hours of application. One day after application labelled glycinebetaine was translocated to all plant parts of turnip rape plants. The results indicate that plants are able to translocate foliar-applied glycinebetaine from their leaves to other organs, and that the use of surfactants accelerates the penetration of foliar-applied glycinebetaine. According to our results glycinebetaine is quite inert end-product in plant cells being mainly phloem-mobile. Moreover, environmental conditions are shown to affect the uptake and translocation rates of foliar-applied glycinebetaine.

Acacia senegal (Mimosoideae) is a leguminous, nitrogen-fixing tree that grows in arid areas of Africa and the Near East. In this work, we studied the effects of drought stress on the development of symbiosis between A. senegal seedlings and Sinorhizobium arboris. We also evaluated if two exogenous compatible solutes, glycine betaine and trehalose, are advantageous for the A. senegal–Sinorhizobium symbiosis and if these solutes are capable of protecting two Sinorhizobium strains from salt stress (NaCl) and osmotic stress induced by polyethylene glycol (PEG 6000). A. senegal seedlings exposed to severe drought stress developed more root hairs than plants grown under moderate stress. After inoculation with the GUS marked S. arboris strain HAMBI 2180 the hairs were deformed but infection threads occurred only occasionally. Non-typically deformed hairs were dwarfed and swollen. Severely stressed roots contained less nodules but more nodule initials than moderately stressed ones. Nodules formed showed a lowered glucuronidase activity and signs of premature senescence. The numbers of culturable rhizobia in soil mix were reduced from 107 to 106 CFU g−1. Thirty days after inoculation severely drought-stressed A. senegal seedlings were wilted. Regarding endogenous glycine betaine, A. senegal appeared to be a non-accumulator plant but was able to translocate foliar-applied glycine betaine into roots. Both glycine betaine (0.01 M) and trehalose (0.01, 0.05 and 0.09 M) protected cell cultures of the wild type S. arboris strain HAMBI 1552 and S. saheli strain HAMBI 1496 from osmotic stress (9 and 17% PEG). In the case of salt stress only trehalose had a favourable effect. Application of 0.0003 M glycine betaine or trehalose into A. senegal soil mix exposed to severe drought stress maintained the numbers of culturable rhizobia at the same level as in moderately stressed soils. The presence of glycine betaine in the soil mix also helped A. senegal seedlings survive under severe drought.