Impact of light on yielding of some Pleurotus sp. strains MAREK SIWULSKI, MIROSŁAWA ZIOMBRA and KRZYSZTOF SOBIERALSKI Department of Vegetable Crops, Poznań University of Life Sciences Dąbrowskiego 159, PL-60-594 Poznań, fungus@up.poznan.pl Siwulski M., Ziombra M., Sobieralski K.: Impact of light on yielding of some Pleurotus sp. strains. Acta Mycol. 47 (1): 65–73, 2012. Light is an important factor deciding about yielding and morphological characters of Pleurotus carpophores. The objective of the research was to ascertain the impact of period and intensity of lighting on yielding and carpophore morphological features of four strains of oyster mushroom. The following strains were investigated: P. ostreatus: PX, K22 and P80 strains, P. pulmonarius: P20 strain. Fluorescent lamps with Day-Light were used to provide light in the cultivation room. The following lighting periods were used: 6, 10 and 14 hours/ day and the applied lighting intensity included: 100, 300, 500 and 700 lx. Lighting exerted a significant impact on yielding. The highest carpophore crop was recorded when the applied lighting intensity was 500 and 700 lx for the period of 14 h/d. The highest mean mass of carpophores was recorded at 14-hour light exposure and 500 and 700 lx lighting intensity. Carpophore morphological features modified by the lighting period and its intensity included the cap diameter as well as the length and thickness of the stem. Key words: oyster mushroom, cultivation, lighting intensity, carpophore, morphological traits INTRODUCTION Species from the Pleurotus genus, including their strains, differ with regard to char- acters of their carpophores (Ziombra, Gembiak 2000; Siwulski et al. 2006). Yields of mushrooms from the Pleurotus genus depend on many factors; apart from genetic properties, also environmental factors play a significant role in this regard (Lelley 1991; Shah et al. 2004). The mycelium of mushrooms from the Pleurotus genus does not require light for its growth (Sharma 2004), nevertheless, light is necessary for the proper de- velopment of carpophores (Olivier 1988; Royse, Zaki 1991). Trukhonovets (1991) maintains that during the period of carpophore development and growth, light is an important factor deciding about yielding and morphological characters of fruiting ACTA MYCOLOGICA Vol. 47 (1): 65–73 2012 66 M. Siwulski et al. bodies. Experiments conducted by the above-mentioned researcher showed that light quantities required for carpophore development can be regulated by shorten- ing the exposure time and increasing the light intensity or, conversely, by lengthen- ing the time of exposure to light and decreasing its intensity. In other words, the total quantity of light is decisive for normal development of carpophores. It should, how- ever, be emphasised that there are significant differences between strains. Selection of profusely fruiting strains and providing optimal conditions for their cultivation are commonly considered to be among key yield-forming factors. Due to considerable variability of the Pleurotus genus, both with regard to mor- phological as well as functional features, many forms of this mushroom have already been selected and are used in cultivation as separate strains. Strains differ among one another with regard to the weight of their carpophores, size and thickness of the pileus as well as the length and thickness of the stem. These traits alter depending on cultivation conditions, although they remain characteristic for the given strain (Curvetto et al. 2002; Siwulski et al. 2006). The objective of the presented research project was to ascertain the impact of light on yielding and carpophore morphological features of four strains of oyster mushroom. MATERIAL AND METHODS The following species and strains of oyster mushroom were investigated: Pleurotus ostreatus Jacq.ex.(Fr.) Kumm. – PX, K22 and P80 strains, Pleurotus pulmonarius (Fr.) Quel. – P20 strain. The evaluation of yields depending on the duration and intensity of lighting exposure was carried out in air-conditioned chambers of the Department of Vegetable Crops, University of Life Sciences in Poznań. The experiment was set up in a random design in four replications and two cultivation cycles. The cultivation substrate was wheat straw cut into chaff of 3-5 cm length. The substrate of approximately 70% moisture content was pasteurised at the tempera- ture of 60°C for the period of 48 hours. After the pasteurisation process, the sub- strate was cooled down to the temperature of 25°C and mixed with oyster mushroom mycelium. The oyster mushroom mycelium as propagation material was produced on wheat grain. The proportion of the applied mycelium in relation to the cultiva- tion substrate was established at 5%. The substrate, together with oyster mushroom mycelium, were placed in perforated polyethylene bags; 10 dm3 in each bag. The process of overgrowing of the oyster mushroom mycelium through the sub- strate took place in darkness in a cultivation facility in which the temperature was maintained at the level of 18-20°C and air humidity – at 80-85%. Once the substrate was overgrown by the mycelium of the examined strains, dif- ferent lighting conditions were applied for the cropping period. Fluorescent lamps with light similar to natural light (Day-Light) were used to provide light in the fa- cilities. The following lighting periods were used: 6, 10 and 14 hours/day and the applied lighting intensity included: 100, 300, 500 and 700 lx. Measurements of the Impact of light on yielding of some Pleurotus sp. strains 67 lighting intensity were performed on the substrate surface with the assistance of a luxmeter L-20. The yield mass in relation to the substrate dry matter was determined and biomet- ric measurements of fruiting bodies were taken. A sample for biometric measure- ments consisting of 40 carpophores was collected randomly from each experimental combination. The diameter and thickness of the cap and length and thickness of the stem were determined. The results comprising yields and morphological traits of carpophores were analysed for mean values from replications and cultivation cycles. The analysis of variance for three-factorial experiments was performed calculating LSD at the significance level of α=0.05. RESULTS Lighting exerted a significant impact on yielding. The highest carpophore crop, ir- respective of the strain, was recorded in combinations where the applied lighting intensity was 500 and 700 lx for the period of 14 h/d. The experimental strains re- sponded differently to the applied light regimes. At lighting intensity of 500 and 700 lx, the highest and non-significantly differing crops were recorded for PX, K22 and P80 strains, whereas P20 strain exhibited the weakest response to changes in the lighting intensity, especially at 14-hour light exposure (Tab. 1). The light exposure of 6 h/d, irrespective of the lighting intensity, resulted in a sig- nificant decline of yields in comparison with 10 and 14 h/d lighting period. The high- est yields were obtained at 14-hour light exposure. Apart from the duration of the light exposure, also light intensity played a significant role. The highest crops were recorded at 500 and 700 lx lighting intensity. Yields obtained in such conditions did not differ significantly irrespective of the period of lighting. Table 1 Pleurotus yield in relation to intensity and period of lighting (g x kg-1 D.M. of substrate) Lighting Strain (h) (lx) PX P20 K22 B80 6 100 300 500 700 188 206 278 346 205 275 290 330 122 138 245 282 182 235 285 296 Mean 256 275 196 250 10 100 300 500 700 228 380 512 522 402 518 622 635 232 326 480 492 330 462 634 780 Mean 411 544 382 552 14 100 300 500 700 426 595 805 830 532 660 668 672 284 398 615 728 325 554 890 912 Mean 664 633 506 670 LSD 0.05 for strain=60, for lighting intensity=86, for period of lighting=82, for interaction=115 68 M. Siwulski et al. It was demonstrated on the basis of analyses of lighting intensity and time inter- relationships that it was not possible to shorten the time of light exposure even when light intensity was increased up to 700 lx. On the other hand, it is not advisable to reduce lighting intensity below 500 lx, if we want to lengthen the duration of light ex- posure at the expense of lighting intensity. The examined strains responded similarly to lighting duration in the 24-hour period. The recorded mean carpophore mass characteristic for a given strain changed following different light exposure of the cultivation. When a 14-hour lighting regime was employed, the mean weight of harvested carpophores was higher in comparison with fruiting bodies grown in 6 or 10-hour regimes. The mean carpophore weight increased together with the length of the lighting period per day. Also lighting in- tensity exerted influence on carpophore weight. When the applied lighting intensity was 100 or 300 lx, carpophores of significantly smaller weight were obtained than at Table 2 Carpophore mean mass of Pleurotus strains in relation to intensity and period of lighting (g) Lighting Strain (h) (lx) PX P20 K22 B80 6 100 300 500 700 22 28 36 42 28 32 32 32 20 20 22 24 26 28 40 42 Mean 32 31 22 34 10 100 300 500 700 38 42 48 50 34 36 38 38 24 36 38 38 32 44 46 48 Mean 45 37 34 43 14 100 300 500 700 40 58 66 68 24 36 48 50 24 34 48 50 36 50 58 60 Mean 58 40 39 51 LSD 0.05 for strain=8, for lighting intensity=8, for period of lighting=10, for interaction=15 Table 3 Cap diameter of Pleurotus strains in relation to intensity and period of lighting (mm) Lighting Strain (h) (lx) PX P20 K22 B80 6 100 300 500 700 22 30 36 34 30 32 36 38 18 20 26 26 22 22 28 32 Mean 31 34 23 26 10 100 300 500 700 32 42 50 53 42 52 52 52 24 32 37 38 28 38 46 46 Mean 44 50 33 40 14 100 300 500 700 38 56 72 74 46 48 52 52 28 38 47 52 32 46 58 62 Mean 60 50 41 50 LSD 0.05 for strain=6, for lighting intensity=8, for period of lighting=6, for interaction=11 Impact of light on yielding of some Pleurotus sp. strains 69 the same period to light exposure but of 500 and 700 lx. However, lighting intensity of 500 and 700 lx applied only for 6 or 10 hours exerted a negative influence on car- pophore weight. The highest weight of fruiting bodies was recorded at 14-hour light exposure and 500 and 700 lx lighting intensity (Tab. 2). Strain P20 was characterised by the weakest response to changes in lighting conditions. The remaining strains were found to respond similarly to changes in both lighting intensity and duration. Cap diameter and thickness were features characteristic for a given strain and, similarly to the carpophore mass, depended on lighting intensity and duration. Car- pophores with the largest and thickest caps were observed in combinations with 14 h/d light exposure and 500 and 700 lx lighting intensity (Tabs 3 and 4). The applied lighting intensity of cultivations affected the length and diameter of mushroom stems (Tabs 5 and 6). Fruiting bodies with the shortest stems were found in strains cultivated for the longest light exposure (14 h/d). In addition, a distinct Table 4 Cap thickness of Pleurotus strains in relation to intensity and period of lighting (mm) Lighting Strain (h) (lx) PX P20 K22 B80 6 100 300 500 700 8 10 12 12 6 6 8 8 6 6 6 6 8 8 10 10 Mean 11 7 6 9 10 100 300 500 700 12 12 14 14 8 9 9 9 8 8 10 10 12 12 14 14 Mean 13 9 9 13 14 100 300 500 700 12 15 17 17 8 10 10 10 10 10 12 12 12 15 16 16 Mean 15 10 11 15 LSD 0.05 for strain=2, for lighting intensity=2, for period of lighting=2, for interaction=2 Table 5 Stem length of Pleurotus strains in relation to intensity and period of lighting (mm) Lighting Strain (h) (lx) PX P20 K22 B80 6 100 300 500 700 40 38 36 36 14 14 12 12 38 38 34 34 38 36 34 34 Mean 38 13 36 35 10 100 300 500 700 40 36 34 32 14 12 12 10 36 34 33 33 34 32 28 26 Mean 36 12 34 30 14 100 300 500 700 36 32 28 26 12 10 10 10 34 26 25 25 34 28 26 26 Mean 31 11 28 28 LSD 0.05 for strain=6, for lighting intensity=8, for period of lighting=3, for interaction=10 70 M. Siwulski et al. tendency was found with decreasing lighting intensity for the development of car- pophores with increasingly long stems. The stem thickness of carpophores declined with decreasing lighting intensity and shortening of time exposure to light. The proportion of stems in the weight of carpophores ranged from 11 to 42% de- pending on strain, lighting intensity and light exposure time. P20 strain was charac- terised by the smallest proportion (11-16%) of stems in carpophores; short stems are typical for this strain and in comparison with other strains, the length of their stems is least dependent on variations in lighting. In the case of the remaining strains, the percentage proportion of the stem weight in the carpophore weight was consider- ably higher ranging from 25 to 42%, depending on the lighting regime. In general, it can be said that the better the lighting conditions, the smaller was the proportion of the stem weight in the carpophore weight. It is true that when lighting conditions Table 6 Stem diameter of Pleurotus strains in relation to intensity and period of lighting (mm) Lighting Strain (h) (lx) PX P20 K22 B80 6 100 300 500 700 8 8 8 9 8 8 10 10 8 8 9 10 9 9 11 11 Mean 8 9 9 10 10 100 300 500 700 9 10 10 12 10 10 10 10 8 9 10 10 8 8 10 10 Mean 10 10 9 9 14 100 300 500 700 10 12 14 14 10 12 12 12 8 8 10 10 8 8 10 10 Mean 13 12 9 9 LSD 0.05 for strain=2, for lighting intensity=3, for period of lighting=2, for interaction=3 Table 7 Proportion of stem in carpophore mass of Pleurotus strains in relation to intensity and period of lighting (%) Lighting Strain (h) (lx) PX P20 K22 B80 6 100 300 500 700 42 38 36 36 16 16 14 14 36 36 32 32 40 36 34 30 Mean 38 15 34 35 10 100 300 500 700 38 35 30 28 15 14 12 12 36 36 30 30 34 32 30 30 Mean 33 13 33 32 14 100 300 500 700 33 30 27 27 13 12 11 11 32 30 27 27 28 26 26 25 Mean 29 12 29 26 LSD 0.05 for strain=5, for lighting intensity=5, for period of lighting=4, for interaction=8 Impact of light on yielding of some Pleurotus sp. strains 71 deteriorated, the stem also became thinner but it also became longer and this caused that the stem weight increased affecting its percentage proportion in the carpophore weight (Tab. 7). DISCUSSION Light, along with other external factors, exerts a significant impact on the growth and development processes of carpophores of mushrooms from the Pleurotus genus. It acts as a signal triggering off various biophysical and biochemical processes ulti- mately leading to morphological and phototrophic reactions (Trukhonovets 1991). In the performed investigations, the size and thickness of the cap and length and thickness of the carpophore stem characteristic for the strain altered under the influence of the applied various lighting regimes. The mean carpophore weight was a trait characteristic for a given strain but dependent on time and intensity of light- ing of cultivations. Also Trukhonovets (1991) reported a dependence of the size of the cap and stem length on lighting intensity. Among important characters affecting salability of fruit- ing bodies is the ratio of the cap size to the stem size. Stems of carpophores of the majority of oyster mushroom species, with the exception of Pleurotus eryngii, are inedible and should be as small as possible. In our investigations, irrespective of the applied lighting regime, the shortest stems were determined in the case of car- pophores of the P20 strain, whereas in the remaining examined strains stems were longer and changed depending on lighting intensity. However, according to literature data, there is no agreement as to the optimal range of lighting intensity recommended in the mushroom cultivation of Pleurotus genus and, depending on individual researchers, this range fluctuates from 300 to 1500 lx (Lelley 1991; Stamets 2000; Oei 2003; Ziombra et al. 2008). In the presented experiments, the optimal lighting intensity to obtain high crops of advantageous carpophore morphological features ranged from 500 to 700 lx for PX, K22 and B80 strains. The examined P20 strain was characterized by the lowest requirements regarding the applied lighting regimes and gave similarly high yields both at 300 and 700 lx lighting intensity. Carpophore morphological traits of the P20 strain remained unchanged throughout the examined range of lighting intensity. The appropriate growth of fruiting bodies is also affected by the length of the lighting period in the 24 h rhythm (Trukhonovets 1991). The research results ob- tained in this study indicate that the applied 14 h lighting regime turned out to be the most favourable for carpophore development. Crops harvested following the 8 h light regime were lower than in the case of 10 h and 14 h light exposure despite the application of higher lighting intensity of 500 and 700 lx. Recapitulating, it was concluded on the basis of the performed experiments that cultivations of the examined species of mushrooms from the Pleurotus genus should receive, during the period of the development and growth of fruiting bodies not less than 10 hours of light per 24 h. In order to obtain carpophores of large caps and short stems, the lighting intensity should not be lower than 500 lx. In addition, the 72 M. Siwulski et al. obtained research results showed that a longer lighting period within the 24 h pe- riod failed to compensate insufficient lighting intensity and, conversely, despite high intensity of lighting, shortening of the lighting exposure time below 10 hours/day is not recommendable. CONCLUSIONS 1. The highest yields of PX, K22 and B80 strains of oyster mushroom were obtained from cultivations exposed to 10 and 14 hours of light per 24 h applying 500 and 700 lx lighting intensity. 2. The P20 strain of oyster mushroom gave similar yields at lighting intensity ranging from 300 through 500 up to 700 lx. 3. The examined oyster mushroom strains developed carpophores with largest caps within the range of lighting considered as optimal to obtain abundant crops. 4. Carpophore morphological features modified by the length of the lighting period and its intensity included the cap diameter as well as the length and thickness of the stem. REFERENCES Curvetto N. R., Figlas D., Devalis R., Delmastro S. 2002. Growth and productivity of different Pleurotus ostreatus strains on sunflower seed hulls supplemented with N-NH4 + and/or Mn (II). Bioresource Technology 84(2): 171–176. Lelley J. 1991. Pilzanbau. Biotechnologie der Kulturspeisepilze. Ulmer, Stuttgart, 404 pp. Oei P. 2003. Mushroom cultivation. Backhuys Publishers Leiden, Netherlands, 429 pp. Olivier J. M. 1988. Les besoins en lumiere dans la culture des Pleurotes. Bull. Fed. Nat. Syndicate Agricol. Cult. Champignons 40: 1433–1439. Royse D. I., Zaki S. A. 1991. Yield stimulation of Pleurotus sp. by dual nutrient supplementation of pasteurized wheat straw. (In:) M.J. Maher (ed.). Science and cultivation of edible fungi. Balkema, Rotterdam: 545–547. Shah Z. A., Ashraf M., Ishtiag M. 2004. Comparative study on cultivatin and yield performance of oyster mushroom (Pleurotus ostreatus) on different substrates. Pakistan J. Nutrition 3 (3): 158–160. Sharma B. B. 2004. Effect of duration of light on radial growth of pink oyster mushroom. Indian Pathol- ogy 57 (2): 234. Siwulski M., Sobieralski K., Ławicka K. 2006. Porównanie plonowania wybranych odmian i krzyżówek boczniaka Pleurotus sp. Folia Horticulturae, Supl. 2: 130–133. Stamets P. 2000. Growing Gourmet and Medicinal Mushrooms. Ten Speed Press, Berkeley, pp.574. Tan Q., Wang ZQ., Cheng JH., Guo Q., Guo L. 2005. Cultivation of Pleurotus spp. in China. Acta Edulis Fungi 12: 338–342. Trukhonovets V. V. 1991. Effect of illumination intensity on the formation of fruiting bodies in Pleurotus ostreatus (Jacq. Fr.) Kumm. Ukr. Bot. Zh. 48 (2): 67–72. Ziombra M., Gembiak R. 2000. Cechy morfologiczne owocników grzybów z rodzaju Pleurotus sp. Rocz. AR Pozn. 31: 573–577. Ziombra M., Czerwińska-Nowak A., Ławicka K. 2008. Wpływ natężenia światła i czasu oświetlenia na plon i cechy morfologiczne owocników kilku odmian boczniaka. Zeszyty Problemowe Postępów Nauk Rolniczych 527: 335–341. Impact of light on yielding of some Pleurotus sp. strains 73 Wpływ światła na plonowanie kilku ras Pleurotus sp. Streszczenie Światło jest ważnym czynnikiem decydującym o plonowaniu i cechach morfologicznych owoc- ników boczniaka. Celem badań było określenie wpływu czasu i natężenia oświetlenia na wiel- kość plonu oraz cechy morfologiczne owocników czterech ras boczniaka. Przedmiotem badań były rasy Pleurotus ostreatus: PX, K22 i P80 oraz rasa Pleurotus pulmonarius:P20. Do oświetle- nia pomieszczeń uprawowych użyto lamp fluoroscencyjnych o świetle zbliżonym do natural- nego. Okres oświetlenia wynosił 6, 10 i 14 godzin na dobę. Zastosowano oświetlenie o natęże- niu 100, 300, 500 i 700 lx. Stwierdzono, że światło wywierało znaczący wpływ na plonowanie. Największe plony owocników uzyskano stosując oświetlenie o natężeniu 500 i 700 lx przez 14 godzin na dobę. Cechami morfologicznymi owocników modyfikowanymi przez długość okre- su oświetlenia i jego intensywność były średnica kapelusza oraz długość i grubość trzonu. 2014-01-02T12:03:35+0100 Polish Botanical Society