nr 579, 2014, 111–120
*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. Łob- zowska 24, 31-140 Kraków, e-mail: twojtowicz@ar.krakow.pl
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 phenologi- cal 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 di- vided 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 shed- ding
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].
112 T. Wójtowicz, A. Zieliński, M. Moś
Zeszyty Problemowe Postępów Nauk Rolniczych In cultivation of grass for seeds one of the main problems is the determination of opti- mal 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 Kra- kow (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 plant- ed 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 ac- cording 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, accord- ing 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 indi- vidual plants. The share of shed seeds mass in the combined seed yield was calculated.
Two-factor variance analyses using the mixed model were carried out. The year of cul- tivation 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 cultiva- tion (Table 1).
Table 1. Significance of differentiation of tested traits of meadow fescue cultivars in the experi- ments conducted in the years 2007–2009
Tabela 1. Istotność zróżnicowania badanych cech odmian kostrzewy łąkowej w doświadczeniach prowadzonych w latach 2007–2009
Trait – Cecha
Sources of variation – Źródła zmienności Years
Lata (A)
Cultivars Odmiany
(B)
Harvest date Termin zbioru
(C)
A × B A × C
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
Plon nasion łączny ** ns ns ns ns
Combined seed yield per 100 panicles
Plon nasion łączny na 100 wiech ** ns ns ns ns
Threshed seeds yield per 100 panicles
Plon nasion omłóconych na 100 wiech ** ns ns ns ns
Shed seeds yield per 100 panicles
Plon nasion osypanych na 100 wiech ** ns ** ns **
Share of shed seeds
Udział nasion osypanych ** ns ** ns **
*significant at p ≤ 0.05 / istotne przy p ≤ 0,05, **significant at p ≤ 0.01 / istotne przy p ≤ 0,01, ns – not sig- nificant / nieistotne.
114 T. Wójtowicz, A. Zieliński, M. Moś
Zeszyty Problemowe Postępów Nauk Rolniczych The earliest date of heading, between 16.1 and 16.6 days from the 1st 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 1st 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 1st 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 cor- relation 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 har- vested panicles was meanly affected by the year of cultivation and the date of harvest (Ta- ble 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).
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 0.347 0.503*
– 0.455*
Days to flowering – Dni do kwitnienia 0.227 0.381
– 0.461*
Plant height – Wysokość rośliny 0.399 0.396
– 0.330
Number of panicles – Liczba wiech 0.399 0.396
– 0.330
Panicle length – Długość wiechy –0.304 –0.058
– 0.189
Combined seed yield – Plon nasion łączny 0.153 –0.179
– 0.472*
Share of shed seeds – Udział nasion osypanych 0.016 –0.106
– 0.646**
Combined seed yield per 100 panicles Plon łączny nasion na 100 wiech
0.313 0.116
– 0.748**
Shed seeds yield per 100 panicles Plon nasion osypanych na 100 wiech
0.528** 0.221
– 0.460*
Average degree of panicle maturity Średni stopień dojrzałości
0.713** 0.582**
– 0.909**
Shed seeds yield – Plon nasion osypanych –0.578** 0.612**
– 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 ze- branych wiech
Cultivar Odmiana
Harvest date Termin
zbioru
2007 2008 2009
Degree of maturity – Stopień dojrzałości
1 2 3 1 2 3 1 2 3
Cykada
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
Skawa
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
Skiba
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
Skra
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
116 T. Wójtowicz, A. Zieliński, M. Moś
Zeszyty Problemowe Postępów Nauk Rolniczych 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 usu- ally 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 concomi- tant 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.
0 0.5 1 1.5 2 2.5 3
0 2 4 6 8 10 12 14 16 18 20 22
I II III
SSD
Weight [1 g per 100 panicles] Masa [1 g na 100 wiech]
shed seeds yield plon nasion osypanych
combined seed yield plon łączny nasion
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. The effect of successive harvest dates on the mass of shed seeds, combined seed yield and average degree of maturity (SSD) in meadow fescue
Rys. 1. Wpływ terminu zbioru na masę osypanych nasion i łączny plon nasion oraz stopień doj- rzałości wiech (SSD) kostrzewy łąkowej
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 Plon nasion
osypanych
Trait Cecha
Degree of maturity
Stopień dojrzałości 2007
Combined seed yield Plon nasion
łączny
0.707** Number of panicles in the
I degree Liczba wiech
I stopnia dojrzałości
0.675** Combined seeds yield per
100 panicles Plon nasion łączny na 100
wiech
–0.173
2008 0.164 –0.715** 0.601**
2009 0.809** –0.500* 0.680**
2007
Shed seeds yield Plon nasion
osypanych
0.642** Number of panicles in the
II degree Liczba wiech
II stopnia dojrzałości
0.539** Threshed seeds yield per 100
panicles Plon nasion omłóconych na
100 wiech
–0.133
2008 –0.638** –0.209 0.332
2009 0.233 –0.150 0.535**
2007
Average degree of maturity Średni stopień
dojrzałości
0.056 Number of panicles in the
III degree Liczba wiech
III stopnia dojrzałości
0.171
Shed seeds yield Plon nasion
osypanych
–0.310
2008 –0.593** 0.465* 0.611**
2009 –0.256 0.755** 0.649**
2007 Combined seed yield per 100
panicles Plon nasion łączny na 100
wiech
–0.222
Combined seed yield Plon nasion
łączny
0.867**
Share of shed seeds Udział nasion
osypanych
–0.360
2008 –0.630** 0.271 0.655**
2009 –0.085 0.490* 0.703**
2007 Threshed seeds yield per 100
panicles Plon nasion omłóconych na
100 wiech
–0.236 – – – –
2008 –0.373 – – – –
2009 –0.058 – – – –
*signifi cant at p ≤ 0.05 / istotne przy p ≤ 0,05, **signifi cant at p ≤ 0.01 / istotne przy p ≤ 0,01.
118 T. Wójtowicz, A. Zieliński, M. Moś
Zeszyty Problemowe Postępów Nauk Rolniczych 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 sec- ond 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 (head- ing 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 shed- ding. At the second date of harvest shed seeds yield obtained during seed shedding induc- tion was two times higher as compared with the first date of harvest.
Fig. 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
Rys. 2. Wpływ lat wegetacji na masę osypanych nasion i łączny plon nasion oraz stopień dojrza- łości wiech (SSD) kostrzewy łąkowej
shed seeds yield plon nasion osypanych
combined seed yield plon łączny nasion
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
0 0.5 1 1.5 2 2.5 3
0 5 10 15 20 25
2007 2008 2009
SSD
Weight [1 g per 100 panicles] Masa [1 g na 100 wiech]
SSD
3. The significant relationship between the yield of shed seeds and the degree of pani- cle 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.
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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 róż- nych terminach zbioru, przy którym straty nasion wynikające z osypywania są najmniej- sze 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 przeprowa- dzono w trzech terminach. Po indukcji osypywania wiechy podzielono na trzy stopnie dojrzałości, a następnie omłócono. Przebieg faz fenologicznych, a także cechy morfolo- giczne roślin i cechy związane z plonem nasion podlegały silnemu wpływowi lat wege- tacji. 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 więk- sza w porównaniu do pierwszego terminu zbioru. Stwierdzono, że wiechy II stopnia doj- rzałości, 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
