Leaf Permeability and its Relationship to Grain Yield and Dry Matter Production in Oats, Avena sativa L.

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  • J. Agronomy and Crop Science, 158, 259270 (1987) 1987 Paul Parey Scientific Publishers, Berlin and HamburgISSN 0931-2250

    SvaldfAB, Svalov, Sweden

    Leaf Permeability and its Relationship to Grain Yieldand Dry Matter Production in Oats, Avena sativa L.

    N . O. BERTHOLDSSON

    Author's address: Dr. N. O. BERTHOLDSSON, Svalof AB, S-26800 Svalov, Sweden.

    With 8 figures and one table

    Received March 10, 1986; accepted April 22, 1986

    AbstractThe leaf permeability of eighteen field grown oat cultivars was examined with the aid of a

    viscous-flow porometer. The relationship of leaf permeability to grain yield was determinedduring two different years. An F4 population and its parents were further studied for frequencydistribution of leaf permeability, total plant dry matter, and grain yield. A plus and minusselection based on leaf permeability measurements was also studied.

    Leaf permeability proved to be cultivar specific, i.e. a cultivar with low values one year alsoexhibited low values next year and vice versa (rank correlation r = 0.55, p < 0.05). This in spiteof that one year was dry and the other wet. Old cultivars had low leaf permeability while newcultivars and new promising breeding lines had, with one exception, high values. Leafpermeability was positively correlated with grain yield, particularly during the wet year (r =0.70, p < 0.001). The population had a population mean of 1.09 porometer units compared to0.95 and 1.18 porometer units for the parents (LSD = 0.08, p < 0.05). Both total dry matterand grain production were positively correlated (p < 0.001) with leaf permeability during grain-filling. The plus and minus selection for leaf permeabiHty within a population showed in thenext generation significantly different population means (0.69 and 0.79 porometer units, LSD =0.08, p < 0.05). Total dry weight and grain yield were six per cent higher (non significant) inthe plus selection than in the minus selection. The possibility to use leaf permeability as aselection criterion is discussed.

    IntroductionEfficient leaf photosynthesis is a basic characteristic in the process of dry matter

    production in plants. Many efforts have been made to use photosynthesis as a selectioncriterion for increased yield (reviewed by GIFFORD and EVANS 1981, SECORet al. 1982). Sofar there has been only minor success, mainly because suggested selection methods havebeen too sophisticated and time consuming to be of any use in practical breeding work.Furthermore, the correlation between the rate of photosynthesis and yield is often weak(ELMORE 1980). Other selection methods, also based on leaf characteristics, have thereforebeen suggested; for instance selection for increased specific leaf weight or stomatalconductance (SHIMSHI and EPHRAT 1975).

    Normally stomata conductance and photosynthesis are correlated with each other.However, the relationship may be more indirect than direct since stomata respond to a

    U.S. Copyright Clearance Center Code Statement: 0931-2250/87/5804-0259$02.50/0

  • 260 N. O. BERTHOLDSSON

    large number of internal and external signals also affecting photosynthesis (FARQUHAR andSHARKEY 1982). Besides that stomatal conductance directly reacts to water stress by achanged water potential of the plant (SHIMSHI 1979).

    Stomatal conductance can be measured with various types of porpnieters, among whichthe viscous-flow porometer is cheap and easy to use (HSIAO and FISCHER 1975). Theoperating principle is that air under pressure is applied to a porometer cup, enclosing aportion of the leaf, and allowed to leak through the leaf to the atmosphere. The pressuredrop during a fixed time is then determined. This value, the leaf permeability (LP), aftercorrection for differences between viscous flow and diffusion, is a measure of stomatalconductance as well as of the intercellular conductance of CO2 diffusion in the leaf.

    Differences in leaf permeability between genotypes therefore could be related todifferent leaf morphologies, different stomatal numbers, different stomata sensitivities forwater stress or possibly avoidance of water stress through a more effective root system(SHIMSHI 1979). They could also be related to an alteration in plant hormone production(COOPER et al. 1972, SKENE 1975, RASCHKE 1979, MICHAEL 1980, FARQUHAR and SHARKEY1982).

    Wheat leaf permeability, measured on plants during their generative stage, has beenpositively correlated to grain yield and total biomass production (SHIMSHI and EPHRATH1975, FISCHER et al. 1981). Leaf permeability measured on spaced F2 plants showed the bestoverall correlation with the F5 yield compared with more than twenty-five other mainlymorphological selection criteria (CIMMYT 1978).

    Most studies so far have been done on irrigated material on sandy soils. The presentexperiment was carried out to study the relationship between leaf permeability and grainyield in material grown on non-irrigated clay soils. The use of permeability measurementsas a rapid screening technique to improve yield is also discussed.

    Material and MethodsPlant material: The experiment was conducted on a heavy clay soil in southern Sweden

    during 1983 to 1985. In 1983 and 1984 eighteen genotypes of oats, selected from the presentbreeding program were used. The material was arranged in two blocks with four replicates. Thefirst block consisted of a mixture of old and modern cultivars and the second block of somemodern cultivars and some new breeding lines. Two of the cultivars, 'Sang' and 'Selma\ werecommon to both blocks. Three of the breeding lines from 1983 were replaced by three otherlines in 1984. Each plot consisted of ten rows, 12.5 cm apart and 10 m long. Nitrogen fertilizerat a rate of 8090 and 100105 kg N/ha in replicate A, C and B, D, respectively, was applied atseeding.

    During 1984 three cultivars Arne, Vital and Stil with high, medium and low leaf pernieability,respectively, were also sown together with unselected F3-seeds from the crosses Ame X Vitaland Vital X Stil, in a randomized block design with four replicates. Each plot consisted of sevenrows, 12.5 cm apart and 1.5 m long. The seeds were planted by hand 5 cm apart in the rows.

    During 1985 the cultivars Ame and Vital and two populations from Ame X Vital, selectedduring 1984 as high and low leaf permeability populations, were machine sown in small (1.5 m )^plots with four replicates.

    The weather during the summer 1983 was much drier than during 1984 and 1985. Rainfall inJune was 45 mm in 1983 compared to 131 and 52 mm in 1984 and 1985, respectively. In July itwas 9, 28 and 69 mm, respectively. The average temperature was identical in June (14.0 "C) forall three years but was different in July (18.3 "C in 1983 compared to 16.0 ''C and 16.3 C in1984 and 1985, respectively).

    Leaf permeability: Leaf permeability (LP) was measured by means of a fast readingporometer (FISCHER et al. 1977). The porometer used was modified so that it was possible to geta digital read-out of the pressure drop for a period of five seconds. Technically this was achievedthrough electronic control of time start and freezing of manometer readings after five seconds.

  • Leaf Permeability and Grain Yield in Oats 261

    Calibration of the porometer, was carried out with glass capillaries of different resistances. Theair flow which is measured by a bubble method, gives leaf permeability in arbitrary porometerunits. From this technique the diffusive conductance was calculated as the square root of viscousconductance (MEiDNERand MANSFIELD 1968). The relation between the manometer readings andthe calculated diffusive conductance was curvi-linear and best described by a power function(r = 0.996, n = 9). An over-pressure of 23 mmHg was used during the measurements. Theporometer cup area was 0.44 cm^.

    Leaf permeability of the flag leaf was measured three times during the grain-filling period, 6,15 and 28 days after fertilization. The measurements were performed between 8.00 a.m. andnoon. In each plot four plants were measured. In 1983 all of the four replicates in each of thetwo blocks were measured separately. In 1984 all replicates in both blocks were measuredtogether. It took 35 minutes to measure each replicate for the twenty cultivars.

    In the plots of the hand sown population material, 25 plants from each of the two populationsand from each of the two parents were marked with a label. These plants were then measuredthree times during the grain-filling period.

    In 1985 a hundred plants each from Arne, Vital and the two selected populations with highand low LP, respectively, were measured once at about four weeks after anthesis.

    Photosynthesis: About four weeks after anthesis in 1984 photosynthesis was measured onflag leaves from five plants from eight of the twenty machine drilled cultivars. The fieldapparatus and procedure for measuring short-term photosynthesis was a modification of that ofSHIMSHI (1969). Both leaf permeability and photosynthesis were measured on the same leaf,although not at the same site.

    Yield and dry matter: At maturity total grain yield was determined after machine harvest ofthe field trial plots. The labelled plants from the hand sown population material were harvestedby hand. Number of shoots of these plants and total dry matter and grain weight weredetermined. In 1985 three rows of each plot were cut by hand and total dry matter and grainweight were determined.

    ResultsGenotypic effects on leaf permeability: There are large variations in leaf permeability

    (LP) between the studied cultivars, especially in 1984 (Fig. 1). Relative LP used in Figure 1is based on average LP values from three different days during grain-filling and differenttimes during the day. Results concerning variations in LP during the season and during theday are reported below. In 1983, a dry and warm year, most cultivars showed similarranking relative to Sang as in 1984 (rank correlation r = 0.55, p < 0.05). There is,however, a general trend that cultivars with lower LP than Sang in 1984 showed a higherLP relative to Sang and vice versa.

    Diurnal changes in leaf permeability: Most of the studies were done between 8.00 a.m.and noon. During this period LP changed due to the influence of both environmental andinternal factors. This is illustrated by the average changes in LP of all cultivars on the 9thand 20th of July 1984 (Fig. 2). On the 9th, a warm and sunny day, average LP decreaseduntil 10.40, while on the 20th, a cloudy and chilly day, LP increased as the weatherimproved during the day. Some cultivars, however, differed in their response to theenvironment and diurnal variations. This is illustrated by the behaviour of the two extrennetypes, where the cultivar with the lowest LP {Stil) showed diurnal changes which werequite different from those of the cultivar with the highest LP {Arne).

    Relationship to grain yield: In 1983 and 1984 the average LP during grain-filling waspositively correlated with grain yield (r = 0.27 n.s. and r = 0.70, p < 0.001), althoughthere is a tendency that cultivars with very high LP have moderate grain yields compared tocultivars with somewhat lower LP (Fig. 3). The opposite is, however, true for one cultivar,Stil, which showed a low LP but gave a high yield.

    The weaker good correlation in 1983 could partly be due to the fact that blocks one andtwo were measured at different occasions and partly be caused by the fact that three

  • 262 N. O. BERTHOLDSSON

    5 0 100

    Porometer units (Re l ) Fig. 1. Relative leaf permeability of differentoat cultivars measured during grain-filling in1983 and 1984. Averages from measure-ments of leaf permeability at three differentoccasions during grain-filling {Sang = 100,n = 4 x 4 ) . Figures within () show thecultivar number as they appeared in block 1in 1984. Cultivars 17, 18, 19 were only

    studied in 1984

    ARNELP8171SV82090SV82089SV81563FIXSANG 6 ,SVEADULAVITALSELMA 5 ,HEDVIGSV 80538

    13191817?0

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    1983 1

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    :*:'!::':-Sx*:-x::-:-:-:-:-i9 9 9 9 9 9 9 9 9 * !

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    2.0

    TIME OF DAYFig. 2. Diurnal changes of leaf permeability on two different days in 1984. a) The 9th of July aday with sunshine but no water stress and b) The 20th of July, a cloudy and chilly day. Bars

    indicate 2 X SE, n = 4

  • Leaf Permeability and Grain Yield in Oats 263

    8 -CO

    7 -X

    0)6 -

    5 -

    120140 0

    0

    00 00

    9 0

    30 2010,

    198301 984

    0.6 0.8 1.0 1.2 1.4

    Porometer unitsFig. 3. The relationship between leaf permeability and grain yield for eighteen different cultivars(see Fig. 1) measured in 1983 and 1984. Very old and new cultivars are identified to the left of

    the symbol with the cultivar number according to Fig. 1. n = 4 x 4

    2 8

    26 -

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    'Ea 22

    J 20

    18 -

    16 -

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    SOL

    SELMA

    FIX

    ITAL

    SANG

    LANTHAVRE

    0.8 1.0 1.2 1.4 1.6 1.8

    Porometer unitsFig, 4. The relationship between leaf permeability and rate of photosynthesis in eight ra.ndomlyselected oat cultivars in 1984. Parallel measurements of leaf permeability and photosynthesis

    were done once on five flag-leaves, (y = 4.75 + 12.03x, r = 0.83, p < 0.01)

  • 264 N. O. BERTHOLDSSON

    cultivars from 1983 were replaced in 1984. It is therefore more accurate to compare theresults from the two years, by only looking at results from the first block. In this reducednumber of cultivars, LP was significantly and positively correlated with grain yield bothyears (r = 0.78 and r = 0.88, p < 0.01). In 1983, however, the difference in LPs affectedgrain yield more than in 1984.

    LP measured at different days were, with exception for the measurements one weekafter anthesis in 1984, positively correlated with grain yield. Furthermore, on twooccasions in 1983 hard wind resulted in very low LP values, negatively (nonsignificantly)correlated with grain yield. New measurements were therefore carried out on less windydays.

    Relationship to leaf photosynthesis: Four weeks after anthesis eight cultivars withdifferent LPs were analyzed for leaf photosynthesis and LP. With exception for the oldcultivar Sol 11 the rate of photosynthesis was positively correlated with LP (r = 0.83,p < 0.01) (Fig. 4). Moreover, photosynthesis and LP were significantly (r = 0.67,p < 0.05) and highly significantly (r = 0.90, p>0.001) correlated with mean grain yield ofall four replicates. In this experiment only five plants in one of the blocks were measuredonce during grain filling.

    30-

    20-

    1 0-

    0 .V

    VITAL

    < 2 0 -

    U.OOClUCO

    1 0 -

    ARNE X VITAL

    30 -

    20 -

    1 0 -

    0

    <

    ARNE

    0.3 0.9 1.2 1.50.6Porometer units

    Fig. 5. Frequency distribution of leaf permeability in three different populations. Each plantwas measured 6, 15 and 28 days after anthesis. Averages are presented, n = 100. Populationmeans 0.95, 1.09, and 1.18 porometer units for Vital, Ame X VitaUndAme, respectively. (LSD

    = 0.08, p < 0.05)

  • Leaf Permeability and Grain Yield in Oats 265

    Relationship to plant height and anthesis date: Both in 1983 and 1984 LP wasnegatively correlated with plant height in the first block of old and new cultivars (r =0.72 and r = 0.82, p < 0.01). In the second block there was no such correlation. LPwas not significantly correlated with anthesis date (r = 0.31 and r = 0.12) or withmaturity date (r = 0.40 and r = 0.34).

    Variations in LP and dry matter production within populations: Individually spacedplants were used to study variations within populations. Three cultivars with low {Stil),medium {Vital) and high {Ame) LP were studied together with populations from thecrosses Stil X Vital and Arne X Vital. Since there were only small differences between Stil,Vital and Stil X Vital the results from this cross have been omitted.

    In Figure 5 the frequency distribution of LP (average of three different measurements) isshown for a 100 plants oiAme, Vital and Arne x Vital. The two cultivars have pronouncedpopulation means at 1.18 porometer units and 0.95 porometer units (LSD = 0.08, p =0.05), respectively, while the population has a less pronounced mean at 1.09 porometerunits. Since the measurements were done during a period of about two hours thepopulation variance is probably higher than if all plants were measured at the same time.The values from the three populations are, however, comparable since the measurementswere done blockwise and not cultivar by cultivar.

    Fig. 6. Leaf permeabilityand total dry weight pershoot. Averages of plantsfrom leaf permeability inter-vals of 0.2 porometer units,(y = 0.96 + 3.44x, r = 0.95,

    p < 0.001)0.5 1.0 1.5

    Porometer units

    In Figures 6 and 7 the relationship between mean of LP and mean of dry matterproduction is shown for groups of plants with an LP interval of 0.2 porometer units.Except for a few plants with low LPs, both total dry matter per shoot and grain yield pershoot are positively and significantly (p < 0.001) correlated with LPs during grain filling.

    Although total biomass production shows similar regression for the two cultivars andthe population (Fig. 6), the regression grain yield vs. LP is about 30 % higher in Vital thanin Ame or the population (Fig. 7).

    J. Agronomy & Crop Science, Vol. 158 (4) 19

  • N. O. BERTHOLDSSON

    Fig. 7. Leaf permeabilityand grain dry weight pershoot. Averages of plantsfrom leaf permeability inter-vals of 0.2 porometer units,(y = 0.53 + 1.62x, r = 0.96,p < 0.001 for Arne andArne X Vital and y = 0.29+ 2.18x, r = 0.98, p < 0.01

    for Vital)

    1.0

    Porometer units

    The correlations between a single LP measurement and various yield components of themature plant are for some characters also positively and significantly correlated with eachother (Table 1). Among the various components total dry weight per shoot and grainweight per shoot are best correlated with LP during the whole grain-filling period (r =0.30.4, p < 0.001).

    Effect of plus and minus selection: In 1985 seeds from plants which in 1984 wereselected for high and low LPs, respectively, from the population Arne X Vital and the twoparents were sown in small plots. Four weeks after anthesis, a hundred plants each of thehigh and low LP selections were measured for LP, and frequency distributions of plants

    Table 1 Correlation coefficients between yield components and leaf permeability measured atvarious days after anthesis in Vital and Arne and the population Arne X Vital, n = 100

    Yield components Leaf permeability6 DAF 15 DAF 28 DAF

    Total dry wt per plantGrain wt per plantNo. shoots per plantTotal dry wt per shootGrain wt per shootStraw wt per shoot

    0.34^'**0.20'=-

    0.27'=-'=- 0.22'=-0.28'=-'=- 0.25'''0.11 n.s. 0.08 n.s.

    0.30'^ - 0.24==-0.40'^ =^='0.17 n.s.

    ', '-"', "''" s ignif icant at 5, 1, 0.1 % , respec t ive ly .n.s. Not significant at 5 % level.Mean correlation coefficient for the three populations studied.DAF = days after fertilization.

  • Leaf Permeability and Grain Yield in Oats 267

    Fig. 8. Frequency distribu-tion of leaf permeability intwo populations from AmeX Vital selected after leafpermeabilit)' in 1984 andmeasured once four weeksafter anthesis in 1985. Popu-lation means 0.69 and 0.79for high and low LP-selec-tions. (LSD = 0.08,

    p < 0.05)

    30-

    20-

    10-

    LOW

    HIGH

    IlI:-SI .

    | I-0.3 0.6 0.9 1.2

    Porometer units1.5 1.8

    were calculated. As shown in Figure 8 the selection of high and low LP plants resulted indifferences in the frequency distribution of the two populations also in the next generation.The high LP population had a population mean of 0.79 porometer units compared to 0.69for the low LP population. The means were significantly different at 0.05 % level. Thecomparison between plus and minus selection in the parents showed, as expected, nosignificant differences in the population means. The average population means for Arneand Vital wcrt 0.87 and 0.73 porometer units, respectively. These means were significantlydifferent at the 0.01 % level.

    At maturity, 0.75 m^ of each plot were cut by hand and total dry matter and grain drymatter were determined. Both total dry matter and grain yield were about 6 per cent higherin the high LP selection than in the low LP selection. The differences were, however, notsignificant.

    DiscussionThe study demonstrates that there are genotypical differences in LP. LP also seems to

    have increased during breeding for improved grain yield. Although the correlationbetween LP and grain yield is highly significant, at least during non-stress conditions,there is a broad spectrum in the relationship, LP vs. grain yield. The reason for this iscomplex.

    Initially LP was measured only on flag leaves, but the relative importance of differentphotosynthesizing organs differs most certainly between cultivars. In oats e.g. the paniclecontributes with up to 40 % of all assimilate translocated to the seeds (NALBORCZYK et al.1981). The panicle may have quite different stomata regulation and hence a variation of thecontribution of the panicle may affect the relationship between flag leaf LP and grain yield.Also variations in the contribution of assimilate from other leaves than the flag leaf may beof importance.

    19=;-

  • 268 N. O. BERTHOLDSSON

    Furthermore, permeability of leaves to air, as measured by the flow porometer, isdependent on stomata resistances on both upper and lower surface (FISCHER et al. 1977,SHIMSHI 1979). The two resistances are in series and hence LP is mostly influenced by thesurface with greatest resistance. Photosynthesis, on the other hand, is less affected, sincestomata resistance on both surfaces acts as parallel resistances to diffusion of CO2 (GAASTRA1959). Therefore genotypic differences in e.g. number of stomata in lower and upperepidermis may affect the correlation between LP and photosynthesis. In fact, the suddendrop in LP in Stil (see Fig. 2 a) could be a result of stomata closure at one surface, which iscompensated by low resistance to CO2 at the other surface.

    Judging from the parallel studies of photosynthesis and LP (Fig. 4) there is, however, atleast under certain conditions, good correlation between photosynthesis and LP (see alsoFISCHER et al. 1981, SHIMSHI 1979). At a very high LP in wheat, LP can increase without acorresponding increase in photosynthesis (SHIMSHI 1979).

    All of this may explain why e.g. Stil, a new high yielding cultivar, has low LP but highyield or why some of the breeding lines have high LP but not a corresponding high grainyield. Therefore selection of plants within a population may have better effect thanselection within different cultivars.

    The fact that the relationship between LP and grain weight can differ between cultivarseven though the relationship between total plant weight and LP is constant (Figs. 6 and 7)suggests that LP influences total production more than grain production. However, thiswill not make LP less attractive as a selection criterion. The reason is that special efforts areneeded to increase total dry matter production to assure future increases in grain yield assoon as optimum harvest index has been reached (AUSTIN 1980).

    The value of LP as a selection criterion is furthermore dependent on its heritability,which most certainly is very complex. Nevertheless the study of Vital and Ame and theunselected population Arne X Vital suggest that it is feasible by crossing and subsequentselection to improve LP. The population mean for LP of Arne X Vital was intermediate tothat of the parents (Fig. 5), and a plus and minus selection resulted in the next generation insmall but significant differences between population means (Fig. 8). '^

    Other studies, such as a study over possible selection criteria in F2 spaced plants,support the view that it is possible to select for increased yield by using LP (ClMMYT 1978).In this study LP, measured three weeks after flowering, showed the best overall correlationwith F5 yield of normally spaced wheat plants (r = 0.33, p < 0.001).

    The value of a selection method for increased yield based on measurements during plantdevelopment is dependent on if a single or at least a limited number of measurements canpredict yields at maturity. The measurements must therefore be more or less uncorrelatedto differences in earliness. From this point of view LP is more useful than photosynthesismeasurements since LP was uncorrelated with the ontogenetic differences both in 1983 and1984 (see also FISCHER et al. 1981). Much of the variation in photosynthesis betweengenotypes can, on the other hand, be referred to differences in days to an thesis (FISCHER etal. 1981, SECORet al. 1982, unpublished own results).

    One disadvantage of the porometer method is, however, that LP showed pronouncedenvironmental and diurnal changes, which was different for various genotypes. Thereforeevery 30 minutes, at least, some kind of control measurement must be included. Measure-ments should also be done at different times of the day. This is less practical if used as aselection method, however, as it would involve keeping records on each plant during theseason. Selection of individual plants for high LP should be carried out about 24 weeksafter flowering. During this period LP is best correlated with dry matter production andyield (Table 1, CIMMYT1978).

  • Leaf Permeability and Grain Yield in Oats 269

    When selecting on cultivar level, on the other hand, LP could be measured on severaloccasions and on different plants to obtain average LP values for each cultivar. In thisstudy with four replicate blocks and four measurements per plot, overall least significantdifference (p < 0.05) between the cultivar means was 0.30 porometer units. As LP variedbetween 0.72 and 1.29 porometer units, significant cultivar effects regarding LP could bedetected, although six to seven measurements per plot might have given more significantdifferences.

    The value of screening for high LP is dependent on if source or sink limitation isprevailing. Under conditions of sink limitation, LP may just reflect source capacity, sincethe source evidently is regulated by the sink (see GIFFORD and EVANS 1981). In this caseselection at earlier stages, when the panicle is differentiating, would probably be moreeffective. Further studies are therefore needed to see if LP at this stage is correlated withe.g. number of flowers per panicle.

    If the source is limiting during grain filling, a situation often prevailing during stressconditions, plants with high LP apparently show less stress symptoms. Photosynthesis isless depressed and sink activity (grain weight) is positively affected. Such plants may berelatively stress insensitive or they can avoid stress by means of a more effective rootsystem (SHIMSHI 1979, FARQUHAR and SHARKEY 1982). A combination of early and late LPmeasurements may therefore be an effective way to improve yield in oats.

    ZusammenfassungDie Blattpermeabilitat und ihre Beziehung zu Kornertragund Trockenmasseproduktion beim Hafer, Avena sativa L.

    Die Blattpermeabilitat von achtzehn im Felde angebauten Hafersorten wurde mit Hilfeeines Massendurchflufi-Porometers bestimmt. Die Beziehung von Blattpermeabilitat zuKornertrag wurde in zwei aufeinanderfolgenden Jahren ermittelt. Aufierdem wurde eineF4-Population und die entsprechenden Kreuzungseltern auf Blattpermeabilitat, Gesamt-trockenmasse und Kornertrag untersucht. Eine auf Blattpermeabilitatsmessungen basiertePlus- bzw. Minusselektion wurde auch analysiert.

    Die Blattpermeabilitat erwies sich als sortenspezifisch, d. h. eine Sorte mit niedrigenWerten im einen Jahr zeigte auch niedrige Werte im folgenden Jahr, und umgekehrt(Rangordnungskorrelation r = 0.55, p < 0.05), und dieses, obwohl das eine Jahr trockenund das nachste feucht war. Alte Sorten waren durch niedrige Blattpermeabilitatswertegekennzeichnet, wahrend neue Sorten und neue, versprechende Ziichtungslinien mit einerAusnahme hohe Werte aufwiesen. Die Blattpermeabilitat war positiv mit dem Kornertragkorreliert, besonders im feuchten Jahr (r = 0.70, p < 0.001). Die Population zeigte einenPopulationsmittelwert von 1.09 Porometereinheiten gegeniiber 0.95 und 0.1.18 fur diebeiden Eltern (GD5% = 0.08). Sowohl Gesamttrockenmasse wie Kornproduktion warenpositiv (p < 0.001) mit der Blattpermeabilitat wahrend der Kornflillungsphase korreliert.Die Plus- bzw. Minusselektionen auf Blattpermeabilitat innerhalb einer Population zeigtenin der folgenden Generation signifikant unterschiedliche Populationsmittelwerte (0.69bzw. 0.79 Porometereinheiten, GDso/^ = 0.08). Gesamttrockenmasse und Komerntewaren 6 % (nicht signifikant) hoher in der Plus- als in der Minusselektion. Die Moglich-keit, die Blattpermeabilitat als Selektionsmerkmal zu verwenden, wird diskutiert.

    I am very grateful to Dr. B. MATTSONfor the use of the breeding material and to Dr. V. STOYand Dr. S. LARSSON for the critical reading of the manuscript. I am also grateful to the SwedishPlant Breeding Board for financial support.

  • 270 N. O. BERTHOLDSSON, Leaf Permeability and Grain Yield in Oats

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