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

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<ul><li><p>J. Agronomy and Crop Science, 158, 259270 (1987) 1987 Paul Parey Scientific Publishers, Berlin and HamburgISSN 0931-2250</p><p>SvaldfAB, Svalov, Sweden</p><p>Leaf Permeability and its Relationship to Grain Yieldand Dry Matter Production in Oats, Avena sativa L.</p><p>N . O. BERTHOLDSSON</p><p>Author's address: Dr. N. O. BERTHOLDSSON, Svalof AB, S-26800 Svalov, Sweden.</p><p>With 8 figures and one table</p><p>Received March 10, 1986; accepted April 22, 1986</p><p>AbstractThe leaf permeability of eighteen field grown oat cultivars was examined with the aid of a</p><p>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.</p><p>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 &lt; 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 &lt; 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 &lt; 0.05). Both total dry matterand grain production were positively correlated (p &lt; 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 &lt; 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.</p><p>IntroductionEfficient leaf photosynthesis is a basic characteristic in the process of dry matter</p><p>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).</p><p>Normally stomata conductance and photosynthesis are correlated with each other.However, the relationship may be more indirect than direct since stomata respond to a</p><p>U.S. Copyright Clearance Center Code Statement: 0931-2250/87/5804-0259$02.50/0</p></li><li><p>260 N. O. BERTHOLDSSON</p><p>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).</p><p>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.</p><p>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).</p><p>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).</p><p>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.</p><p>Material and MethodsPlant material: The experiment was conducted on a heavy clay soil in southern Sweden</p><p>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.</p><p>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.</p><p>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.</p><p>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).</p><p>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.</p></li><li><p>Leaf Permeability and Grain Yield in Oats 261</p><p>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^.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>ResultsGenotypic effects on leaf permeability: There are large variations in leaf permeability</p><p>(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 &lt; 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.</p><p>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).</p><p>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 &lt; 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.</p><p>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</p></li><li><p>262 N. O. BERTHOLDSSON</p><p>5 0 100</p><p>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</p><p>studied in 1984</p><p>ARNELP8171SV82090SV82089SV81563FIXSANG 6 ,SVEADULAVITALSELMA 5 ,HEDVIGSV 80538</p><p>13191817?0</p><p>916</p><p>78</p><p>12111015</p><p>LANTHAVRE 1SOL IIGULDREGNSEGER 1STIL</p><p>fx*x*:i 1</p><p>432</p><p>14</p><p> a a a a ^* * * * * * * *</p><p>* * * * * * * *</p><p> - .Vaa*a^*a'a</p><p>; ; ; % ; ; ; </p><p>* * * * * * * * *</p><p> a a a a a a a</p><p> a I</p><p>* </p><p>p'^ 'a a ap a *_*^*^*^*^</p><p>! * * " " ' " " '* * * * * * * *) </p><p>' *B*a*a*a*a*a a&gt; * </p><p> a a a a a a a a a a a a</p><p> a a</p><p>'XvMvI'a'a'a'a'a'a'B'a9 9 9 9 9 9 9 9B a a a a a *</p><p>1%'X'X'X'a a a a a B a a</p><p> a a a 4</p><p>9 9 9 9 9 9 9 9</p><p>1983 1</p><p>:X:::X::::\:;:;:;:::.:.:.;.:.:.:^^&gt;&gt;X::!X:X::v::X::vy* * * * a a ^ a ^ ^ ^ , , * J</p><p>:*:'!::':-Sx*:-x::-:-:-:-:-i9 9 9 9 9 9 9 9 9 * ! </p><p> a a a a , , , ! , . , , , </p><p>a ' a ' a ' B a a a a a a a a a a t ^ J B a a a B a a a a a a a [ _ 4</p><p>9 9 * * * * . . . . . . ^ - f . ' J</p><p> a a a a a a a a a a a) a a a a a a B B 4</p><p> a B B ^ * a a a a a a a |</p><p>a * B * a * a B * a a a a a a B B I Ia B a a a a a a a a a a l l</p><p>a A A a a a i t l l T ' J</p><p>p a a B a a a B a a B 9 9 9 9 9 9 9 9 9 9 9 9 9</p><p> ^ * a 9 9 9 9 * 9 9 9 * * 9 9 9</p><p> - - - _ _ _ _ - *</p><p>* * * * * 9 9 * 9 * V ' l</p><p>B B a a a B a a a B a a l9 9 9 9 9 9 9 9 9 9 9 1</p><p> B a a a a B a a a a a l</p><p>:-&gt;x '^x-Xv;|a * a * B a a * * * a a l</p><p>' a ' a ' * B a a J 1a ^ , , , , , , , 1 1</p><p>a a a B B a a a al 1</p><p>* a * a * a ' a a a a 4i 1a a a a a a a a l 1a a a a a a a ! J</p><p>a a a a a a ] 1.....1 1</p><p>r-SSSSl'l^ 1 9 8(4</p><p>2.0</p><p>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</p><p>indicate 2 X SE, n = 4</p></li><li><p>Leaf Permeability and Grain Yield in Oats 263</p><p>8 -CO</p><p>7 -X</p><p>0)6 -</p><p>5 -</p><p>120140 0</p><p>0</p><p>00 00</p><p>9 0</p><p>30 2010,</p><p> 198301 984</p><p>0.6 0.8 1.0 1.2 1.4</p><p>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</p><p>the symbol with the cultivar number according to Fig. 1. n = 4 x 4</p><p>2 8</p><p>26 -</p><p>^ 2 4 -]</p><p>'Ea 22</p><p>J 20</p><p>18 -</p><p>16 -</p><p>14 -</p><p>Sv82089I Lp8i71</p><p> SOL</p><p>SELMA</p><p>FIX </p><p>ITAL</p><p> SANG</p><p>LANTHAVRE</p><p>0.8 1.0 1.2 1.4 1.6 1.8</p><p>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</p><p>were done once on five flag-leaves, (y = 4.75 + 12.03x, r = 0.83, p &lt; 0.01)</p></li><li><p>264 N. O. BERTHOLDSSON</p><p>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 &lt; 0.01). In 1983, however, the difference in LPs affectedgrain yield more than in 1984.</p><p>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 y...</p></li></ul>