WEEDS IN ORGANIC PRODUCTION OF PEPPER

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1 Biblid: (15) 19; 5; p UDK: Original Scientific Paper Originalni naučni rad WEEDS IN ORGANIC PRODUCTION OF PEPPER (Capsicum annuum L.) - BIOINDICATORS OF HABITAT CONDITIONS KOROVI U ORGANSKOJ PROIZVODNJI PAPRIKE (Capsicum annuum L.) BIOINDIKATORI USLOVA STANIŠTA Branka LJEVNAIĆ-MAŠIĆ, Ljiljana NIKOLIĆ, Dejana DŽIGURSKI University of Novi Sad, Faculty of Agriculture, Trg Dositeja Obradovića 8, 21 Novi Sad, Serbia brana@polj.uns.ac.rs ABSTRACT The aim of the study was to examine the weed flora structure and to identify possible differences in habitat conditions. The research was conducted in the crops of pepper grown according to the principles of organic production at two localities (Ljutovo and Stara Pazova). A total of 29 weed species was noted (8 common species). Floristically richer was the locality Stara Pazova. Five species are invasive in the region of Vojvodina. There were no significant differences in ecological conditions of habitats, except slightly larger differences in species diversity in relation to ecological indices for the temperature and humidity of habitat. Strong anthropogenic influence was indicated by significant dominance of therophytes in both localities. At Stara Pazova there were also perennial geophytes and hemikryptophytes, which indicate the stability of weed flora and worse weed control measures. Most of the weeds have a root system that penetrates to the depth of 5-1 cm. Approximately of the weeds begin to bloom in June and flowering ends in September. Approximately of the weeds form seed that can survive in soil from to 1 years. In both localities dominated by weed-ruderal species and species that develop under the strong anthropogenic influence. Key words: organic production, pepper, weeds, bioindicators, biological characteristics, ecological analysis. REZIME Cilj rada je bio da se sagleda struktura korovske flore i utvrde moguće razlike u uslovima staništa koji pogoduju razvoju korova. Istraživanje je vršeno u zasadu paprike, gajene po principima organske proizvodnje, na dva izdvojena lokaliteta (Ljutovo i Stara Pazova). Konstatovano je ukupno 29 korovskih vrsta (8 zajedničkih vrsta). Floristički bogatiji bio je lokalitet Stara Pazova sa 24 vrste, dok je u Ljutovu konstatovano 13 korova. Konstatovano je i 5 vrsta invazivnih za područje Vojvodine. Između ispitivanih lokaliteta nisu utvrđene značajnije razlike u ekološkim uslovima staništa, sem nešto veće razlike u divergentnosti vrsta u odnosu na ekološke indekse za temperaturu i vlažnosti staništa. U Ljutovu, dominiraju korovske vrste tolerantne na povećanu koncentraciju soli u zemljištu, dok u Staroj Pazovi dominiraju vrste tolerantne na teške metale. Na jak antropogeni uticaj, na ispitivanim agroekosistemima, ukazuje znatna dominacija terofita na oba lokaliteta. U Staroj Pazovi je konstatovano i prisustvo višegodišnjih geofita i hemikriptofita koje upućuju na stabilnost korovske flore i na nešto lošije mere suzbijanja korova. Većina prisutnih korova ima korenov sistem koji prodire na dubinu 5-1 cm što dodatno otežava njihovo suzbijanje i otežava razvoj gajene biljke. Oko zabeleženih korova počinje da cveta u junu, a većina cvetanje završava u septembru. Najduže vreme cvetanja imaju Stellaria media (januar-decembar) i Senecio vulgaris (mart-novembar), dok najkraće cveta Setaria viridis (jun). Oko korova formira semena koja mogu da prežive u zemljištu od do 1 godina. Na oba lokaliteta, dominiraju korovsko-ruderalne vrste i vrste koje se razvijaju pod jakim antropogenim uticajem. Ključne reči: organska proizvodnja, paprika, korovi, bioindikatori, biološke karakteristike, ekološka analiza. INTRODUCTION The importance of organic production is reflected in the protection and sustainable use of biological diversity, in the protection of the environment, natural resources, human and animal health by using biological and mechanical methods, as opposed to using synthetic materials (Lazić and Lazić, 8). Arable areas under organic products are growing from year to year. However, their share in the total agricultural area is still low. By September 13, in Serbia was 238 ha under organic vegetable production (123 ha with organic status and 115 ha under conversion), which is only 3 of the total area under organic production in Serbia (Kalentić et al., 14). Vegetables, with fruit, are the most important organic product in the European market. In addition, pepper, besides onion, garlic and potatoes, is one of the organic products from Serbia with significant potential in the European Union. Pepper (Capsicum annuum L.) is an annual plant from tropical America where it is transferred to other continents. Its fruit (berry) is one of the most important sources of vitamin C. In addition, it contains vitamins B1, B2, B3 and carotene, organomineral compounds, organic acids and sugars (Tucakov, 1997). Because of its quality, it is used in cooking and in the prevention of many diseases (cardiovascular disease, kidney disease, anaemia, strengthening the immune system, etc.). Dander of pepper comes from the alkaloid capsaicin, which speeds up the metabolism and is used to reduce weight and for cleansing the blood from triglycerides (Tucakov, 1997). It belongs to the species with distinct requirements for water and heat air and soil. Pepper's requirements for water depend on the intensity of solar radiation, temperature and relative humidity. Excessive or reduced soil moisture slows down the growth of the root system and aboveground organs. The yield of peppers affects the temperature of water for irrigation, and the most favourable temperature of 25 C to 27 C. The optimal air temperature for germination of pepper is about 3 C, a soil of 25 C. It is very sensitive to low temperatures. Pepper is a 266 Journal on Processing and Energy in Agriculture 19 (15) 5

2 typical heliophilic plant that requires intense brightness of about 3 klx. Pepper favors the humus-rich soils, such as fertile alluvial soils, neutral to slightly acid reaction. It is sensitive to salinity and oxygen content in the soil. Organic fertilizers have a special significance in its production (Đurovka, 8). However, infestation of crops is a current problem in organic production. Weeds are a limiting factor that reduces yield and quality of cultivated plants, with respect to completely exclude the application of the herbicides. Weed control in organic production should be based on maintaining the soil without weed seeds and their organs for vegetative propagation, their suppression before fruiting, etc. Just understanding the ecological and biological characteristics of weeds facilitates propose concrete measures (preventive, biological, physical, mechanical) and adequate time for weed control in organic production. Therefore, the aim of the study was to examine weed flora structure and to identify possible differences in habitat conditions that allow and favour the development of identified weeds, based on the ecological analysis and the analysis of biological characteristics of weed species (life forms, the depth of the root system, flowering time, seed longevity), categorization of species according to their sites and the analysis of species tolerance to the anthropogenic impact, in crops of pepper, cultivated according to the principles of organic production at two separate sites. MATERIAL AND METHOD Floristic investigations of weeds, in organic production of pepper, were performed during the vegetation period 12 to 14. in two separate localities registered for organic production in Ljutovo (locality I "Mamužić") and Stara Pazova (locality II "Koluvija"), Fig. 1. The present weed flora was determined according Josifović ( ), a species characterized as invasive are according to IASV (11). Index of floristic similarity between the studied localities is presented according to Sørensen (1948). Based on the value of ecological indices according to Landolt (1), an ecological analysis of the flora was made with the aim to identify possible differences in habitat conditions that allow and favour the development of identified weeds. Because this is a relatively new literature, which is necessary in ecological analysis of the flora, we have given explanations of each of the analysed ecological indices. Were analysed bioindicators values that characterize the climate and soil conditions: Temperature (T), i.e. the average air temperature during the growing season of a plant, where the lower values of this ecological index point to a plant distribution in higher altitude areas (with lower temperatures), while higher values indicate that the species occurs in the lower regions (with higher temperatures), Tab. 1. Continentality (K) characterises the appearance of a species with respect to the continentality of the climate. The higher values indicate on dry air and a large variation in temperature, while the lower values indicate that the species occurs in areas with humid air and a small variation of temperature Light (L) i.e. the average light quantity received in the habitats, where a lower value means that the plant is growing in the shade, and a higher value that grows on the illuminated habitat Moisture (F) signifies an average soil moisture during the growing period on the site where the species most frequently occur. Low values indicate low soil moisture and high values high soil moisture Moisture variability (W) indicates the variability of moisture in the soil during a year, where lower values indicate less variation in soil moisture and vice versa Reaction (R) i.e. the chemical reaction of the soil, characterises the content of free H-ions in the soil, where lower values indicate acid soils, and higher values correspond to soil rich in bases Nutrients (N) characterise the nutrient content in soils (nitrogen and often also phosphorus). Lower values indicate to poor nutrients in soil, and vice versa, a higher value to rich nutrient contents in the soil Salt tolerance (S) where the label s indicates that the species is tolerant an increased salt content in the soil, and the designation ss means that the plant mostly depends on places with increased salt content in the soil Heavy metal tolerance (M), where m indicates a certain tolerance of plant to heavy metals in the soil, which may indicate on the possible contamination of soil with heavy metals Humus (H) characterises the humus content in the soil, i.e. the totality of dead organic matter in/on the soil. Lower values indicate to little humus content and higher values indicate to much humus content in/on the soil. Aeration (D) i.e. the oxygen supply of the soil, where lower values of this index indicate badly aerated soils and higher value good aeration. According to the Landolt (1), an adaptation of the plants to temperature (T) and moisture (F) characterized by a bioindicators values 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5, to continentality (K), light (L), the chemical reaction (R) and the content of nutrients in the soil (N) with 1, 2, 3, 4 and 5, and the variability of soil moisture during the year (W), humus content in the soil (H) and soil aeration (D) with 1, 3, and 5. We also analysed the biological characteristics of the species: - Life forms (Újvárosi, 1973), - Root depth (WT) which specifies the depth of the root penetration in the soil (Landolt, 1), - Seed longevity (SU) indicates the known durability of the seed buried in the soil under favourable conditions (Landolt, 1) - The time of flowering (Čanak et al., 1978), - Categorization of species according to site (Kojić et al., 1972) and - Influence of man on site condition (EM) specifies the ability of species to tolerate the human impact on growth conditions (Landolt, 1). RESULTS AND DISCUSSION Floristic investigations of weed flora in the crops of peppers, grown according to the principles of organic production, were performed at two separate localities (locality I - Ljutovo and locality II Stara Pazova), Fig. 1. During the vegetation period 12-14, it was recorded a total of 29 species, of which five species are invasive in Vojvodina: Amaranthus retroflexus L., Ambrosia artemisiifolia L., Datura stramonium L., Portulaca oleracea L. and Sorghum halepense (L.) Pers. (IASV 11), Tab. 1. At both localities are dominated by broadleaved weeds from the class Magnoliopsida. Comparing the weed flora between the Journal on Processing and Energy in Agriculture 19 (15) 5 267

3 two studied localities showed significant floristic differences in the number of present species as well as differences in species diversity. In the locality I were recorded thirteen, while a total of twenty-four weed species were recorded in the locality II (Tab. 1). Only 8 species are common, i.e. present at both studied localities. Index of floristic similarity according to Sørensen (1948) amounts to Fig. 1. The investigation area (I - Ljutovo; II Stara Pazova) Ecological analysis of recorded weed flora in the crops of pepper, grown according to the principles of organic production at two separate localities, showed that among the examined localities there was no significant difference in ecological habitat conditions (Fig. 1, Tab. 2). However, as far as the ecological index for temperature (T), in the locality I is dominated species that like favourable temperature conditions (T ), while in the locality II are present species adapted to different average air temperatures during the growing season (T T , T ), which indicates that in this locality appear slightly larger fluctuations in temperature during the growing season (Fig. 1, Tab. 2). Average values of ecological indices are shown in Table 2. At both localities, are dominated species adapted to medium relative air humidity with moderate daily and annual variations of temperature and moderate winter temperatures (I K ; II K ), Graph. 1, Tab. 3. Both habitats are favourable for the development of weed species that tolerates shade only temporary or short period (I L 4-1 ; II L ), Graph. 1, Tab. 3. In both investigated localities are dominated species adapted to moderately moist soil (I F ; II F ), but is also a significant presence of a species characterized by ecological indices F 2.5 and F 2 which indicates on fresh and moderately dry habitat (Graph. 1, Tab. 3). More than 5 of plants present in both localities suggests that soil moisture varies little throughout the year (I W ; II W ), Graph. 1, Tab. 2. Table 1. Weed flora in organic production of peppers (Locality I - Ljutovo, Locality II - Stara Pazova) Plant species Locality I II Agropyrum repens (L.) Beauv. + Amaranthus retroflexus L. + + Ambrosia artemisiifolia L. + Anagallis arvensis L. + Bilberdykia convolvulus (L.) Dum. + + Chenopodium album L. + + Cirsium arvense (L.) Scop. + Convolvulus arvensis L. + Cynodon dactylon (L.) Pers. + Datura stramonium L. + + Daucus carota L. + Euphorbia helioscopia L. + Herniaria glabra L. + Hibiscus trionum L. + Hordeum murinum L. + Poa trivialis L. + Polygonum aviculare L. + Polygonum lapathifolium L. + + Portulaca oleracea L. + + Senecio vulgaris L. + Setaria viridis (L.) P.B. + Solanum nigrum L. + + Sonchus arvensis L. + Sorghum halepense (L.) Pers. + + Stachys annua L. + Stellaria media (L.) Vill. + Taraxacum officinale Weber. + Trifolium repens L. + Urtica dioica L. + Total Legend: invasive species Soil of both investigated localities can be characterized as a slightly acidic to neutral weak (I R , R - 3:38; II R , R ), but also is a significant presence of species that favour the neutral to alkaline chemical reaction of the soil (Figure 2). The dominance of a species characterized by ecological index N 4 (I N ; II N ) in both investigated localities refers that a soil is rich in nutrients (especially nitrogen), Figure 2. Approximately 5 of the weed species present in the locality I possesses tolerance to increased salt concentration (Ss ), while on the locality II dominated weeds tolerant to heavy metals (Mm ), which may indicate on possible soil contamination on this locality by heavy metals (Figure 2). 268 Journal on Processing and Energy in Agriculture 19 (15) 5

4 ,5 4 4, ,5 2 2,5 3 3, s m T K L F w R N S M H D CLIMATE INDICATORS SOIL INDICATORS Fig. 2. Ecological analysis of weed flora in the crops of peppers T (temperature): 3 montane, 3.5 lower montane and uuper colline, 4 - colline, 4.5 warm colline, 5 very warm colline; K (continentality): 2 suboceanic, 3 suboceanic and subcontinental, 4 subcontinental; L (light): 3 semi-shade, 4 well lit places, 5 full light; F (moisture): 1.5 dry, 2 moderately dry, fresh, 3 moderately moist, 3.5 moist; W (moisture variability): 1 moisture little varying, 2 - moisture moderately varying, 3 - moisture strongly varying; R (reaction): 3 weakly acid to weakly neutral, 4 neutral or alkaline; N (nutients): 2 infertile, 3 medium infertile to medium fertile, 4 fertile, 5 very fertile and over-rich; S (salt tolerance): s salt tolerant M (heavy metal tolerance): m - heavy metal tolerant; H (humus): 1 little or no humus, 3 high humus content; D (aeration): 1 bad aeration, 3 moderate aeration, 5 good aeration On investigation localities, the soil is moderately rich in humus and moderately aerated with respect to the absolute dominance of species characterized by ecological indices H 3 and D 3 (Figure 2, Table 2). On a strong anthropogenic influence indicates significant dominance of therophytes (I ; II ) on the both studied agro ecosystems. The most common are annual T 4 therophytes, on both localities, that germinate in the spring and seeds are formed at the end of the summer (I ; II ). Similar results were also obtained by researching other organic vegetable production (Ljevnaić-Mašić et al., 12; Džigurski et al., 13; Ljevnaić-Mašić et al., 13). However, at the locality II there were also recorded 25. of perennial Table 2. Average values of ecological indices of weed flora in the crops of peppers in two separate localities The average value of ecological indicator Locality Climate indicators Soil indicators T K L F W R N H D Locality I (Ljutovo) Locality II (Stara Pazova) geophytes and 12.5 of hemicryptophytes which indicate the stability of the weed flora, but also of slightly worse weed control measures (Figure 4). Most of the identified weeds, at both localities, have the largest number of roots that penetrate to a depth of 5-1 cm, which also indicates that the soil is moderately aerated and the ecological analysis for soil aeration also proving this fact (Figure 4, Table 2). On the locality I dominate the weed whose roots penetrates to a depth of 25 to 1 cm (characterized by bioindicators values 2.5 and 3), while on the locality II, in addition to these, develop and weeds with a slightly shallower root system (<25 cm), Figure 4. The presence of a significant number of annual and perennial weeds, with deep root systems (characterized by values of 3.5 and 4.5) on the locality II, indicates to certain degree more stable weed flora. Bearing in mind that the depth of the roots of weed species is certainly one of the factors that further complicates their control, on the locality II is necessary to intensify appropriate measures of weed control. Journal on Processing and Energy in Agriculture 19 (15) 5 269

5 Weed control in organic production should be based on maintaining the soil without organs for vegetative propagation of weeds, but above all, the maintenance of soil without weed seeds. Therefore, the knowledge of the time of flowering of weed species is important for taking adequate measures of weed control prior to their fruiting. Approximately of identified weeds begin to bloom in June, and most weed species flowering ends in September (Figure 3). From identified weed species, the longest flowering time have Stellaria media (L.) Vill. (January- December), Senecio vulgaris L. (March-November), Euphorbia helioscopia L. (April-November) and Urtica dioica L. (June- November), while the species Setaria viridis (L.) P. B. (June), Agropyrum repens (L.) Beauv. (May-June), Cynodon dactylon (L.) Pers. (June-July) and Sorghum halepense (L.) Pers. (June- July) have the shortest flowering time (Graph. 2). Approximately of identified weeds, on both locations, are characterized by the value 4 according to Landolt (1). This means that their seeds can survive in soil from to 1 years (I ; II 59.9 ) which further complicates their control (Figure 4). Both localities are significantly dominated by weed-ruderal species (I ; II ). They are followed by segetal weeds (I ; II -.83 ) and ruderal weeds (I ; II ), Figure 4. This attitude of certain groups, clearly indicates on intensive human impact on the studied agro ecosystems (Kojić et al., 1972; Nikolić et. al., 12). On the investigated habitats is a significant dominance of species that develop under the strong anthropogenic influence (I ; II ), characterized by values 4 and 5, which is understandable considering that these are two anthropogenic agro ecosystems (Figure 4). Based on the analysis of ecological and the biological characteristics of identified weeds, in the crops of peppers, can be concluded that on the studied agro ecosystems is significant anthropogenic impact, especially in the locality I, while in the locality II is necessary to intensify appropriate measures of weed control. The knowledge of the ecological and the biological characteristics of weeds facilitate proposing of concrete measures (preventive, biological, physical and mechanical) and adequate time for weed control in organic production, which completely excluded the use of herbicides. Plant species Amb. art. Son. arv. Urt. dio. Che. alb. Poly. lap. Sol. nig. Sta. ann. Ama. ret. Bil. con. Con. arv. Dat. str. Dau. car. Cir. arv. Hib. tri. Poa tri. Por. ole. Cyn. dac. Sor. hal. Set. vir. Agr. rep. Her. gla. Hor. mur. Tri. rep. Ana. arv. Poly. avi. Tar. off. Eup. hel. Sen. vul. Ste. med. I II III IV V VI VII VIII IX X XI XII Month Fig. 3. Time of flowering of weed species in the crops of pepper 27 Journal on Processing and Energy in Agriculture 19 (15) 5

6 , T1 T2 T4 G1 G3 H2 H3 Life forms 1,5 2,5 3 3,5 4,5 Root depth Seed longevity KR R S Categorization according to site Influence of man Fig. 4. Biological characteristics of weed flora in the crops of peppers Life forms: T therophytes, G geophytes, H hemicryptophyte; Root depth: 1.5 about at the root depth in <25cm, about at the root depth in 25-5cm, 3 root depth in 5-1cm, about 9 at the root depth in 5-1cm, about 95 at the root depth in 1-cm;Seed longevity: 2 1 to 5 years, 3 5 to years, 4 to 1 years, 5 more than 1 years;categorization according to site: KR weed-ruderal plant, R ruderal plant, S segetal weed, LK weed of meadows and pastures;influence of man on site conditions: 3 urbanoneutral plant, 4 moderately urbanophilous plant, 5 strictly urbanophilous plan Locality I (Ljutovo) Locality II (Stara Pazova) CONCLUSION The research of weed flora in the crops of peppers, grown according to the principles of organic production at two separate locations in Ljutovo (locality I Mamužić ) and Stara Pazova (locality II Koluvija ), showed significant floristic differences, Journal on Processing and Energy in Agriculture 19 (15) 5 271

7 both in the number of species present, as well as species diversity. It was noted that a total of 29 weed species (I - 13 species; II - 24 species), of which only eight species in common i.e. present at each studied locality. Five species are invasive in Vojvodina: Amaranthus retroflexus L., Ambrosia artemisiifolia L., Datura stramonium L., Portulaca oleracea L. and Sorghum halepense (L.) Pers. At both localities are dominated by broadleaved weeds class Magnoliopsida. Based on the ecological analysis ascertained weed flora, among the studied localities were no significant differences in ecological conditions of habitats, except some slightly larger differences in the species diversity in relation to ecological indices for the temperature (T) and humidity (F) of habitat. Based on the ecological analysis, it was found that examined agroecosystems are moderately warm to warm (I T - 4:4; II T ) and good lighting habitats (I L - 4:; II L ) with dominance of species adapted to the conditions of the mean relative humidity and moderate daily and annual temperature fluctuations (I K ; II K ). These are moderately moist to moderately dry habitats (I F ; II F ), with low or moderate humidity variation during the year (I W - 1:54; II W - 1:59), slightly acidic to slightly neutral (I R - 3:38; II R ), rich in nutrients (I N - 4.; II N ), moderately rich in humus (I H ; II H - 3.) and moderately aerated (I D - 2:54; II D ). On the locality I dominate the weed species tolerant to increased salt concentration in the soil (Ss ), while at the locality II dominate species tolerant to heavy metals (Mm ), which indicates on potential soil contamination with these substances. Analysis of the life forms of identified weeds species showed dominance of hemitherophytes on both investigated localities (I ; II ), which indicates on strong anthropogenic influence. On the stability of the weed flora and slightly worse weed control measures indicate a significant presence of perennial geophytes (25. ) and hemikryptophytes (12.5 ) on the locality II where is necessary to intensify appropriate measures of weed control. The root system of most of the identified weeds penetrates to a depth of 5-1 cm, which further complicates their control. The longest flowering period has Stellaria media (L.) Vill. and the shortest flowering time has Setaria viridis (L.) P.B. Approximately of the identified weeds form seed that can survive in soil from to 1 years, which further complicates their control (I ; II ). At both localities, significantly dominate the weed-ruderal species (I ; II ) and species that develop under the strong anthropogenic influence (I ; II ). Based on the ecological analysis and the analysis of the examined biological characteristics of weeds can be concluded that on the investigated agro ecosystems is significant anthropogenic impact, especially in the locality I, while the locality II is necessary to intensify appropriate measures of weed control. The knowledge of the ecological and the biological characteristics of weeds facilitate proposing of concrete measures and adequate time of weed control in organic production. ACKNOWLEDGEMENTS: This study is part of the project TR3127 titled»organic agriculture: Improvement of production by use of fertilizers, biopreparates and biological measures subsidized by the Ministry for Education and Science of the Republic of Serbia. REFERENCES Čanak, M., Parabućski, Stanija, Kojić, M. (1978). Ilustrovana korovska flora Jugoslavije. Matica srpska, Novi Sad, Srbija. Džigurski, D., Nikolić, Lj., Ljevnaić-Mašić, B. (13). Weed flora in organic onion production Allium cepa L. 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