THE EFFECT OF DEGREE OF PANICLE MATURITY ON SEED YIELD AND YIELD COMPONENTS IN MEADOW FESCUE (FESTUCA PRATENSIS HUDS.) *

Zeszyty Problemowe Postępów Nauk Rolniczych nr 579, 2014, 111 120 THE EFFECT OF DEGREE OF PANICLE MATURITY ON SEED YIELD AND YIELD COMPONENTS IN MEADOW FESCUE (FESTUCA PRATENSIS HUDS.) * Tomasz Wójtowicz, Andrzej Zieliński, Maria Moś University of Agriculture in Krakow Summary. The aim of the research was to determine the degree of panicle maturity that reduces yield loss caused by seed shedding and allows reaching the optimal seed yield in four meadow fescue cultivars: Cykada, Skawa, Skiba and Skra. Observations of phenological phases and measurements of morphological traits were made in the years 2007 2009. Individual plants were harvested in three dates. After induced shedding, panicles were divided into three degrees of maturity. In the first year, heading and flowering began at the earliest date. The highest plants from 112.7 to 114.3 cm were obtained in the second year of cultivation. In succeeding harvest dates maturity of panicles was rising simultaneously with the increase in shed seeds yield, which on the second date showed over two-times increase as compared to the first date. The decisive effect on threshed and shed seeds yield had panicles characterized by second degree of maturity, which constituted 25 40% of the total amount of harvested panicles. Key words: meadow fescue cultivars, optimal date of harvest, seed production, seed shedding INTRODUCTION The seed production of grasses in Poland according to Domański [2004] is not able to satisfy the demand of area of grasslands. The cause of this situation is low yield of grass seeds and low area of seed cultivation. The lack of domestic cultivars of grasses concerns primarily meadow fescue. In the year 2008 a small increase in area of cultivation for seed was noted [Oleksiak 2008]. *This research was supported by the Polish Ministry of Agriculture and Rural Development as a part of basic research for biological progress in crop production. Corresponding author Adres do korespondencji: Tomasz Wójtowicz, Uniwersytet Rolniczy w Krakowie, Wydział Rolniczo-Ekonomiczny, Katedra Hodowli Roślin i Nasiennictwa, ul. Łobzowska 24, 31-140 Kraków, e-mail: twojtowicz@ar.krakow.pl

112 T. Wójtowicz, A. Zieliński, M. Moś In cultivation of grass for seeds one of the main problems is the determination of optimal date of harvest [Domański 2004]. It is a result of many causes arising from perennial cultivation of grasses, for example high variability of the number of inflorescences in subsequent years [Deleurean et al. 2013]. Another problem but equally important in seed production is seed shedding. This phenomenon is well known in wild grass species as a condition of seed spreading. In cultivated species of grasses resistance to seed shedding is very desirable but the way of its inheritance is highly complicated, thus the efficiency of selection for high resistance in breeding program is very low. Furthermore, the weather conditions during seed ripening and harvesting affect intensity of seed shedding. The aim of research was to determine the effect of degree of panicle maturity obtained in succeeding dates of harvest that reduces seed yield loss caused by shedding and allows reaching the optimal seed yield. MATERIAL AND METHODS Four meadow fescue cultivars: Cykada, Skawa, Skiba and Skra, bred by Małopolska Hodowla Roślin HBP sp. z o.o. (Poland) were tested. Field experiments were set up on August 2006 at Experimental Station of University of Agriculture in Prusy near Krakow (N 50 07 03 and E 20 05 13 ). Randomized complete block design was used considering six replications. Every block consisted of ten plants of each cultivar planted in rows with spacing 50 60 cm. In the years 2007 2009 observations of heading and flowering were performed and the length of the stems and panicles was measured, according to OECD methodology [1968]. Twelve individual plants of tested cultivars, six plants in each of two blocks, omitting marginal plants in every row, were harvested in three succeeding dates. The first date of harvest occurred at 87 stage of growth according to BBCH scale and the next two dates were delayed for three days. Directly after harvest, all panicles obtained from each plant were subjected to induced shedding with the use of modified laboratory shaker. The weight of shed seeds was estimated. On the basis of the coloration, panicles were assigned to three degrees of maturity, according to Anderson s scale [1981]: I degree rachis and lower part of panicle are green, II degree rachis and upper part of panicle are yellow, III degree rachis and whole panicle are yellow. The number of panicles assigned to each degree of maturity was used to calculate the average degree of maturity (SSD) according to the formula: n1 1+ n2 2 + n3 3 SSD = n1 + n2 + n3 where n1, n2 and n3 are the numbers of panicles assigned to consecutive degrees of Anderson s scale. Assigned panicles were threshed and the weight of obtained seeds was measured. The threshed and shed seeds were joined in order to estimate the combined seed yield for individual plants. The share of shed seeds mass in the combined seed yield was calculated. Zeszyty Problemowe Postępów Nauk Rolniczych

The effect of degree of panicle maturity on seed yield and yield components... 113 Two-factor variance analyses using the mixed model were carried out. The year of cultivation was the first factor (random) and the investigated cultivars were the second factor (fixed). The blocks were analyzed as a representation of distinguished harvest dates. The evaluation of the correlations between traits and years of cultivation was performed on the basis of the Pearson linear correlation coefficient. RESULTS AND DISCUSSION In available literature there are only a few results concerning the effect of panicle maturity on seed yield [Anderson 1981, Binek and Moś 1992, Binek 1996] and sowing value [Wójtowicz and Moś 2011]. The results are mostly focused on the elements of yield structure [Falkowski et al. 1996, Goliński 2000, Kitczak and Czyż 2001, Martyniak and Martyniak 2002, Das and Taliaferro 2009] and cultivation [Goliński 2001, Vučković et al. 2003, Kitczak et al. 2010, Skinder et al. 2011] which affect seed yield. The course of phenological phases, morphological traits and the elements of yield structure of meadow fescue plants differed significantly in succeeding years of cultivation (Table 1). Table 1. Significance of differentiation of tested traits of meadow fescue cultivars in the experiments conducted in the years 2007 2009 Tabela 1. Istotność zróżnicowania badanych cech odmian kostrzewy łąkowej w doświadczeniach prowadzonych w latach 2007 2009 Trait Cecha Years Lata (A) Sources of variation Źródła zmienności Cultivars Odmiany (B) Harvest date Termin zbioru (C) A B Days to heading Dni do kłoszenia ** * ns Days to flowering Dni do kwitnienia ** ** ns Plant height Wysokość rośliny ** ns ns Panicle length Długość wiechy ** ns ns Average degree of panicle maturity Średni stopień dojrzałości ** * ** ns ** Combined seed yield łączny ** ns ns ns ns Combined seed yield per 100 panicles łączny na 100 wiech ** ns ns ns ns Threshed seeds yield per 100 panicles omłóconych na 100 wiech ** ns ns ns ns Shed seeds yield per 100 panicles osypanych na 100 wiech ** ns ** ns ** Share of shed seeds Udział nasion osypanych ** ns ** ns ** A C *significant at p 0.05 / istotne przy p 0,05, **significant at p 0.01 / istotne przy p 0,01, ns not significant / nieistotne. nr 579, 2014

114 T. Wójtowicz, A. Zieliński, M. Moś The earliest date of heading, between 16.1 and 16.6 days from the 1 st of May, was observed in the first year of cultivation, and in the following two years the heading was delayed by 2 3 days. The course of flowering was similar. The earliest date of this phase between 25.9 and 26.9 days from the 1 st of May was observed in the first year of cultivation. In the second and third year flowering began at the later dates, 32.1 32.6 days and 33.1 34.8 days from the 1 st of May, respectively. Moreover, the significant variation of observed phenological phases was found for tested cultivars, which agrees with the results of Rutkowska and Kamiński [1988]. Cultivar Skawa was characterized by delayed heading and flowering phases, by 0.9 days on average, as compared to the other cultivars. The highest plants, which height ranged from 112.7 to 114.3 cm on average, were obtained in the second year of cultivation. In two other years the height ranged from 83.2 to 98.5 cm on average. The longest panicles were found in the first year of cultivation. In that date the length ranged from 18.3 to 19.8 cm on average, whereas in the next two years it was lower by 2 3 cm. The variability of these traits calculated on the basis of coefficient of variation was very low and did not exceed 10%. According to Martyniak [2005], mentioned traits are indirectly connected with plant density but highly correlated with seed yield. The correlation coefficients between succeeding years of cultivation, calculated for the course of phenological phases, morphological indices and traits conditioning seed productivity were in most cases significant for the second and third year. Average degree of panicle maturity and shed seeds yield were the only traits for which a significant interrelationship between all analyzed years was found (Table 2). The share of panicles assigned to each degree of maturity in the total amount of harvested panicles was meanly affected by the year of cultivation and the date of harvest (Table 3). During the harvest conducted at three successive dates a significant increase in the average degree of panicle maturity accompanied by an increase in the yield of shed seeds was observed (Fig. 1). The significant differences in the yield of shed seeds between the first and the next two harvest dates were found. In the third harvest date the yield of shed seeds was lower, probably as a result of the shedding which had occurred before harvest. However, despite the significant variation in the degree of panicle maturity and the share of shed seeds there was no significant effect of mentioned traits on combined seed yield per 100 panicles. These results are in accordance with previous publication [Wójtowicz et al. 2009] in which a direct effect of degree of panicle maturity on the seed yield was not found. While indirect effect of that trait on the seed yield was poor and unstable in succeeding years of cultivation. The years of cultivation had a great effect on the interrelationship between panicle maturity indices and the yield structure traits. Coefficients of correlation between the yield of shed seeds and the number of panicles assigned to each of the three degrees of maturity were significant in the case of the first degree of maturity in succeeding years of cultivation. However, only in the second and third year an increase in the number of panicles assigned to that degree caused a decrease in the mass of shed seeds. For the second degree of panicle maturity the significant and positive coefficients of correlation were found in the first year as well as for the third degree in the second and third year of cultivation (Table 4). Zeszyty Problemowe Postępów Nauk Rolniczych

Table 2. Correlation coefficients for yield structure traits (n = 24) in 2008 and 2009 Tabela 2. Współczynniki korelacji cech struktury plonu nasion (n = 24) w 2008 i 2009 roku Trait Cecha 2008 2009 Days to heading Dni do kłoszenia Days to flowering Dni do kwitnienia Plant height Wysokość rośliny Number of panicles Liczba wiech Panicle length Długość wiechy Combined seed yield łączny Share of shed seeds Udział nasion osypanych Combined seed yield per 100 panicles Plon łączny nasion na 100 wiech Shed seeds yield per 100 panicles osypanych na 100 wiech Average degree of panicle maturity Średni stopień dojrzałości 0.347 0.503* 0.455* 0.227 0.381 0.461* 0.399 0.396 0.330 0.399 0.396 0.330 0.304 0.058 0.189 0.153 0.179 0.472* 0.016 0.106 0.646** 0.313 0.116 0.748** 0.528** 0.221 0.460* 0.713** 0.582** 0.909** 0.578** 0.612** Shed seeds yield osypanych 0.540** *significant at p 0.05 / istotne przy p 0,05, ** significant at p 0.01 / istotne przy p 0,01. Table 3. The share of panicles assigned to each degree of maturity in the total amount of harvested panicles Tabela 3. Udział wiech przyporządkowanych do danego stopnia dojrzałości w łącznej liczbie zebranych wiech Cultivar Odmiana Cykada Skawa Skiba Skra Harvest date Termin zbioru 2007 2008 2009 Degree of maturity Stopień dojrzałości 1 2 3 1 2 3 1 2 3 I 32.8 36.9 30.4 37.0 35.8 27.2 43.9 31.8 24.3 II 30.0 33.5 36.5 11.6 31.0 57.4 19.0 22.9 58.1 III 24.6 32.4 43.1 4.5 23.8 71.8 10.6 12.5 76.9 I 37.1 33.2 29.7 50.4 34.2 15.4 77.0 14.1 8.8 II 35.4 42.8 21.8 19.0 41.0 40.0 38.7 22.1 39.2 III 19.6 38.0 42.4 7.6 31.8 60.7 26.0 15.3 58.7 I 46.5 30.8 22.7 53.8 28.3 17.9 61.7 23.7 14.6 II 29.9 39.3 30.8 19.1 40.4 40.5 28.3 19.4 52.3 III 13.0 28.3 58.6 3.3 22.1 74.6 13.8 12.1 74.1 I 44.5 33.3 22.2 50.0 33.7 16.3 60.3 20.8 18.9 II 27.3 38.1 34.7 15.6 35.2 49.2 31.5 22.3 46.2 III 26.8 42.5 30.7 7.2 27.6 65.3 29.4 27.3 43.4

116 T. Wójtowicz, A. Zieliński, M. Moś Weight [1 g per 100 panicles] Masa [1 g na 100 wiech] 22 20 18 16 14 12 10 8 6 4 2 0 I II III shed seeds yield plon nasion osypanych combined seed yield plon łączny nasion SSD 3 2.5 2 1.5 1 0.5 0 SSD LSD (α = 0.05) = 0.78 LSD (α = 0.05) = 2.31 LSD (α = 0.05) = 0.07 NIR (α = 0.05) = 0.78 NIR (α = 0.05) = 2.31 NIR (α = 0.05) = 0.07 Fig. 1. Rys. 1. The effect of successive harvest dates on the mass of shed seeds, combined seed yield and average degree of maturity (SSD) in meadow fescue Wpływ terminu zbioru na masę osypanych nasion i łączny plon nasion oraz stopień dojrzałości wiech (SSD) kostrzewy łąkowej The significant effect of the years of cultivation on degree of maturity, shed seeds yield and combined seed yield was found (Fig. 2). The highest combined seeds yield was observed in the first year of cultivation as a result of the longest panicles formation. Martyniak [2005], as well as Das and Taliaferro [2009], reported a significant relationship between the seeds yield and yield components: panicle length (r = 0.576 at p 0.01) and seed number per panicle (r = 0.720 at p 0.01). According to Deleurean et al. [2013], in succeeding years of cultivation grasses usually produce lower number of generative stems which in consequence affects a decrease in the seeds yield. In our study, a significant decrease in the combined seed yield observed in the second and third year of cultivation was also the result of increase in shed seeds yield. The positive and indirect effect of shed seeds yield on the combined seed yield, particularly in the third year of cultivation, was found in previous Wójtowicz et al. [2009] study. As a consequence of the increase in degree of panicle maturity there was a concomitant increase in shed seeds yield. This relationship was the main cause of a decrease in combined seed yield at the first and second harvest date. At the third date of harvest this relationship was not found and the yield of shed seeds was not precisely estimated because of an intensive seed shedding which has taken place before the panicles were harvested. Zeszyty Problemowe Postępów Nauk Rolniczych

The effect of degree of panicle maturity on seed yield and yield components... 117 Table 4. Correlation coefficients of maturity indices and yield structure traits (n = 24) Tabela 4. Współczynniki korelacji wskaźników dojrzałości i cech struktury plonu (n = 24) Year Rok Trait Cecha Number of panicles Liczba wiech Trait Cecha Shed seeds yield osypanych Trait Cecha Degree of maturity Stopień dojrzałości 2007 0.707** 0.675** 0.173 Number of Combined Combined seed panicles in the seeds yield per yield I degree 100 panicles 2008 0.164 0.715** 0.601** Liczba wiech łączny I stopnia łączny na 100 dojrzałości wiech 2009 0.809** 0.500* 0.680** 2007 0.642** Number of Threshed seeds panicles in the yield per 100 Shed seeds yield II degree panicles 2008 0.638** 0.209 0.332 osypanych Liczba wiech II stopnia dojrzałości 0.539** omłóconych na 100 wiech 0.133 2009 0.233 0.150 0.535** 2007 0.056 0.171 0.310 Number of Average degree panicles in the Shed seeds of maturity III degree yield 2008 0.593** 0.465* 0.611** Średni stopień Liczba wiech dojrzałości III stopnia osypanych dojrzałości 2009 0.256 0.755** 0.649** 2007 0.222 0.867** 0.360 Combined seed yield per 100 Combined seed Share of shed panicles yield seeds 2008 0.630** 0.271 0.655** Udział nasion łączny na 100 łączny osypanych wiech 2009 0.085 0.490* 0.703** 2007 Threshed seeds 0.236 2008 yield per 100 panicles 0.373 2009 omłóconych na 100 wiech 0.058 *significant at p 0.05 / istotne przy p 0,05, **significant at p 0.01 / istotne przy p 0,01. nr 579, 2014

118 T. Wójtowicz, A. Zieliński, M. Moś 25 3 Weight [1 g per 100 panicles] Masa [1 g na 100 wiech] 20 15 10 5 2.5 2 1.5 1 0.5 SSD 0 2007 2008 2009 shed seeds yield plon nasion osypanych combined seed yield plon łączny nasion SSD 0 LSD (α = 0.05) = 1.36 LSD (α = 0.05) = 2.46 LSD (α = 0.05) = 0.116 NIR (α = 0.05) = 1.36 NIR (α = 0.05) = 2.46 NIR (α = 0.05) = 0.116 Fig. 2. Rys. 2. The effect of the years of vegetation on mass of shed seeds, combined seed yield and average degree of panicle maturity (SSD) in meadow fescue Wpływ lat wegetacji na masę osypanych nasion i łączny plon nasion oraz stopień dojrzałości wiech (SSD) kostrzewy łąkowej The coefficients of correlation between the degree of panicle maturity and combined seed yield, threshed seeds yield as well as shed seeds yield, calculated for the second and third year of cultivation, were significant and positive. The panicles assigned to the second degree of maturity accounted for 25 40% of the total number of harvested panicles regardless of the year of harvest and had the greatest effect on the combined seed yield. The tested cultivars had an effect only on the course of phenological phases (heading and flowering) and the maturity of panicles (Table 1). Differences in the earliness of heading and flowering observed for tested cultivars were not confirmed by a degree of panicle maturity (r from 0.015 to 0.356). CONCLUSIONS 1. The years of cultivation had a great effect on the course of phenological phases, the length of stems and panicles as well as the traits affecting seeds yield. The earliness of heading and flowering and also the plants height were the highest in the first year. 2. The increase in maturity of panicles was accompanied by intensified seed shedding. At the second date of harvest shed seeds yield obtained during seed shedding induction was two times higher as compared with the first date of harvest. Zeszyty Problemowe Postępów Nauk Rolniczych

The effect of degree of panicle maturity on seed yield and yield components... 119 3. The significant relationship between the yield of shed seeds and the degree of panicle maturity was found. The panicles assigned to the second degree of maturity, which accounted for 25 40% of the total harvested panicles irrespective of the date and year of harvest, had a decisive effect on the intensity of seed shedding and combined seed yield. The ratio between the number of panicles of the first and third degree of maturity had also a great importance. REFERENCES Anderson S., 1981. Relationship between dry matter and seed yield in grasses. W: Breeding high yielding forage varieties combined with high seed yield. Report of the meeting of the EUCARPIA Fodder Crops Section, Merelbeke-Gent, Belgium, 49 56. Binek A., 1996. Osobnicza zmienność cech warunkujących produktywność nasienną odmian kupkówki pospolitej, Dactylis glomerata L. Biul. IHAR 199, 81 87 (in Polish). Binek A., Moś M., 1992. Zmienność i współzależność cech warunkujących plon nasion wybranych odmian traw gazonowych. Biul. IHAR 181/182, 273 283 (in Polish). Das M.K., Taliaferro C.M., 2009. Genetic variability and interrelationships of seed yield and yield components in switchgrass. Euphytica 167, 95 105. Deleuran L.C., Kristensen K., Gislum R., Boelt B., 2013. Optimizing the number of consecutive seed harvests in red fescue (Festuca rubra L.) and perennial ryegrass (Lolium perenne L.) for yield, yield components and economic return. Acta Agric. Scand. Sect. B Soil Plant Sci. 63(1), 1 10. Domański P., 2004. Rynek nasienny traw w Polsce. Hod. Rośl. Nasienn. 1, 26 42 (in Polish). Falkowski M., Kukułka I., Kozłowski S., 1996. Wykształcanie pędów generatywnych a plonowanie plantacji nasiennych traw. Biul. IHAR 199, 99 107 (in Polish). Goliński P., 2000. Czynniki determinujące plonowanie plantacji nasiennych Festuca rubra. Łąkarstwo w Polsce (Grassland Science in Poland) 3, 31 41 (in Polish). Goliński P., 2001. Efektywność nawożenia azotem w produkcji nasion Lolium perenne L. Rocz. Akad. Rol. Pozn., Rozprawy Naukowe 321, 1 103 (in Polish). Kitczak T., Czyż H., 2001. Wpływ ilości wysiewu na plon nasion dwóch odmian kostrzewy czerwonej (Festuca rubra L.) i życicy trwałej (Lolium perenne L.) na glebie lekkiej. Zesz. Probl. Post. Nauk Rol. 474, 293 299 (in Polish). Kitczak T., Czyż H., Sarnowski A., 2010. Wpływ nawożenia mineralnego NPK na plon nasion odmiany Asterix Festuca arundinacea. Łąk. Pol. 13, 93 100 (in Polish). Martyniak D., 2005. Wpływ ilości wysianych nasion na obsadę roślin i plonowanie odmian gazonowych kostrzewy czerwonej (Festuca rubra L.) w uprawie na nasiona. Biul. IHAR 237/238, 259 267 (in Polish). Martyniak J., Martyniak D., 2002. Wpływ ilości wysianych nasion na obsadę roślin i plonowanie Lolium perenne w uprawie na nasiona. Łąk. Pol. 5, 145 154 (in Polish). OECD, 1968. Guide to the methods used in plot tests and to the methods of field inspection of herbage seed crops. OECD, Paris. Oleksiak T., 2008. Rynek nasion roślin rolniczych. Hod. Rośl. Nasienn. 3, 12 21 (in Polish). Rutkowska B., Kamiński J., 1988. Fazy rozwojowe gatunków i odmian traw z zależności od terminu pierwszego pokosu oraz warunków siedliskowych. Zesz. Probl. Post. Nauk Rol. 366, 53 60 (in Polish). nr 579, 2014

120 T. Wójtowicz, A. Zieliński, M. Moś Skinder Z., Szczepanek M., Wilczewski E., 2011. Effect of rate and time of nitrogen fertilization on the yield and chemical composition of autumn regrowth of red fescue cultivated for seeds. Acta Sci. Pol. Agric. 10(2), 105 115. Vučković S., Simić A., Ćupina B., Stojanović I., Stanisavljević R., 2003. The effect of vegetation area size on grass seed yield. Journal of Agricultural Sciences 48(1), 125 134. Wójtowicz T., Binek A., Moś M., 2009. Correlations and path analysis of the components of Festuca pratensis seed yield. Łąk. Pol. 12, 223 232. Wójtowicz T., Moś M., 2011. Wpływ stopnia dojrzałości wiech na wartość siewną nasion kostrzewy łąkowej (Festuca pratensis Huds.). Łąk. Pol. 14, 147 160 (in Polish). WPŁYW STOPNIA DOJRZAŁOŚCI WIECH NA PLON NASION I ELEMENTY STRUKTURY PLONU KOSTRZEWY ŁĄKOWEJ (FESTUCA PRATENSIS HUDS.) Streszczenie. Celem pracy było określenie stopnia dojrzałości wiech uzyskanego w różnych terminach zbioru, przy którym straty nasion wynikające z osypywania są najmniejsze i pozwalają na uzyskanie optymalnego plonu. Badania przeprowadzono w latach 2007 2009 na roślinach czterech odmian kostrzewy łąkowej: Cykada, Skawa, Skiba i Skra. Każdego roku wykonywano obserwacje faz kłoszenia i kwitnienia oraz pomiary biometryczne wysokości roślin i długości wiech. Zbiór pojedynczych roślin przeprowadzono w trzech terminach. Po indukcji osypywania wiechy podzielono na trzy stopnie dojrzałości, a następnie omłócono. Przebieg faz fenologicznych, a także cechy morfologiczne roślin i cechy związane z plonem nasion podlegały silnemu wpływowi lat wegetacji. W pierwszym roku wegetacji kłoszenie i kwitnienie rozpoczynało się najwcześniej. Spośród badanych odmian najpóźniejszą okazała się odmiana Skawa. W drugim roku średnia wysokość roślin wahała się od 112,7 do 114,3 cm, natomiast najdłuższe wiechy obserwowano w pierwszym roku wegetacji (od 18,3 do 19,8 cm). W kolejnych terminach zbioru stopień dojrzałości wiech wzrastał, jednocześnie indukcja osypywania ujawniła przyrost masy utraconych nasion, która w drugim terminie zbioru była dwukrotnie większa w porównaniu do pierwszego terminu zbioru. Stwierdzono, że wiechy II stopnia dojrzałości, które stanowiły 25 40% ogólnej liczby zebranych wiech niezależnie od terminu i roku zbioru, miały decydujący wpływ na plon nasion omłóconych i osypanych. Równie istotne znaczenie miał stosunek między liczbą wiech I i III stopnia dojrzałości. Słowa kluczowe: odmiany kostrzewy łąkowej, optymalny termin zbioru, produkcja nasion, osypywanie nasion Zeszyty Problemowe Postępów Nauk Rolniczych