EFFECT OF BANANA PLANT EXTRACTS ON GERMINATION AND SEEDLING GROWTH OF SOME VEGETABLE CROPS

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1 Bangladesh j. crop sci. 2006, 17 (1): EFFECT OF BANANA PLANT EXTRACTS ON GERMINATION AND SEEDLING GROWTH OF SOME VEGETABLE CROPS S. Roy, M. Asaduzzaman, M.H.R. Pramanik and A. K. M. A. Prodhan Department of Crop Botany Bangladesh Agricultural University Mymensingh-2202, Bangladesh (Received on 18 May, 2006) Abstract An experiment was carried out at the Plant Ecology Laboratory of the Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, during the period from February to May, 2005 to investigate the effects of water soluble extracts from different parts of banana plant on seed germination and seedling growth of some vegetable crops. The test crops were lettuce, red amaranth, amaranth, radish, cucumber, ribbed gourd, bean and okra. The test solutions used as treatments were control (only distilled water) and the extracts (100%) from different parts of banana plant (rhizome, root, leaf sheath and leaf lamina) diluted to 15%, 25% and 50% with distilled water. Seeds of the test plants were sown on two layered tissue paper saturated with the extracts as per treatment in petridishes with six replications. The plant extracts showed a significant inhibition on germination in all the test crops compared to control. Among the extracts from different parts of banana plant, extract from rhizome showed strongest inhibition on the seed germination and seedling growth of the test crop. The test plant species responded differently to the rhizome extract and the lettuce seedlings were found most sensitive. The germination and seedling growth of other test plants were decreased with increase in concentration of the extracts and the highest inhibitory effect was observed in 100% concentration. Key words: Banana plant, extracts, germination, seedling growth, vegetable crops. Introduction Banana (Musa sp.) is an important fruit crop in Bangladesh and has a potential to reduce dependency of rice. It is one of the cheapest, most plentiful and nourishing of all fruits (Khader et al., 1995). Banana has high calorific and nutritional value. Carbohydrate content in the banana pulp can be as high as 36.4 % (Bajpai et al., 1995). Banana is particularly rich in vitamin C and also contains significant amounts of several other vitamins (INIBAP, 1987). Banana is a very popular fruit in Bangladesh and cultivated round the year. Total production of banana was metric tons in an area of acres with an average yield of t ha -1 (BBS, 2004). The yield is quite low compared to other banana growing countries of the world like Argentina (34 t ha -1 ) and Costa Rica (33 t ha -1 ) (FAO, 2002). In respect of total production, it ranks second position among the major fruits grown in Bangladesh (BBS, 2004) and comprises about 42% of the total fruit production (Haque, 1988). Banana is propagated by sucker (an offshoot from the parent rootstock). Ratooning (production of succeeding crop from parental rootstock in the same land without ploughing) is a common practice followed for banana cultivation. Generally, banana cultivation in a land is not fruitful after two consecutive ratoonings. Because in ratooned banana, yield declines drastically this is commonly attributed to decrease in soil fertility or disease infectation. However, application of adequate fertilizers was found to be ineffective for harvesting high yield from consecutive ratoon crop of banana. Many researchers have recommended to replace the old rhizomes of mother plants for better

2 236 BANANA PLANT EXTRACTS AND VEGETABLE SEEDS yield in ratooned banana. Recently, leftover residues of sugarcane (ratooning) (Chou, 1992), rice (Pramanik et al., 2001) and many other crops (Inderjit et al., 1995) have been reported to cause growth inhibition on the succeeding crops. Many inhibitory chemicals have been identified from the leftover residues of these crops. Thus, intoxication effects of the banana plant residues on the growth and yield of ratooned crop cannot be fully ignored. Recently plant exudates from different parts of plants have been used to check whether the exudates contain any toxic chemicals through bioassay (Dinardo et al., 1998). Different bioassay procedures have been suggested by many researchers in allelopathic studies (Enhellig et al., 1985). Thus, extracts from different parts of banana plants may contain some toxic chemicals which may cause growth and yield reduction in rationed banana. The present investigation was undertaken to evaluate the inhibitory effects of different extracts from banana plants on germination and seedling growth of some vegetable crops, and also to find out the extracts that are most inhibitory to the vegetable crops. Materials and Methods Source of test plant materials: Twelve month s old banana plants were collected from Horticultural Field Laboratory, Bangladesh Agricultural University, Mymensingh. Disease free, clean, fresh and healthy seeds of eight different vegetable crops were collected from BADC office, Mymensingh and were used as test crop. These were lettuce (Lactuca sativa var. Green wave), red amaranth (Amaranthus gangeticus var. Altapetti), amaranth (Amaranthus oleraceus var. Panna), radish (Raphanus sativus var. Tasakishan), cucumber (Cucumis sativus var. Sahi 50), ribbed gourd (Lufa acutangula var. Prince), bean (Lablab niger var. IPSA 2), and okra (Abelmoschus esculentus var. Anamika). Preparation of extracts: Hundred grams each of rhizome, root, pseudostem (leaf sheath) and leaf lamina were used for extraction in the experiment. Each plant part (100 g) was chopped into small pieces and ground to paste with distilled water in a mortar with pestle. The mixture was filtered through filter paper Whatman no. 1 and the filtrates were collected in measuring cylinders. The extract volume was adjusted to 100 ml with distilled water for bioassay and this was considered as stock solution. As the stock solution (100%) strongly inhibited the growth of test plants, each extract was diluted with distilled water to a series of concentrations. The stock solution (100%) and its dilutions (50%, 25% and 15%) were considered as experimental treatments with distilled water as control. Relative phytoxicity of rhizome, root, pseudostem and leaf lamina extract was evaluated (Experiment 1) for lettuce and the rhizome extract was further chosen to reveal its inhibitory effects on the other test vegetable crops in the subsequent experiment (Experiment 2). Bioassay technique: Double layers of tissue paper were used in glass petridishes (15 cm diameter) as substratum of germination and subsequent seedling growth. Five ml extract of each diluted test solution was added to moisten the substratum. Thirty seeds of each vegetable crop were placed uniformly by forceps in each treated petridish with six replications and were kept in dark at room condition. Germination (seed that emerged about 2 mm radicle was considered as germinated) was recorded daily and calculated as percent germination. After four days, of radicle and plumule of the seedlings were recorded (radicle and plumule was measured from root-shoot zone to the tip of the radicle and leaf, respectively by a graduated scale) to evaluate inhibition potential of the extracts.

3 ROY et al 237 Data analysis: Data recorded on germination percentage and growth parameters were compiled and analyzed following the common statistical package (MSTATC software). The mean differences among the treatments were adjudged by DMRT (Gomez and Gomez, 1984). Experiment 1 Results and Discussion Banana plant extracts (rhizome, root, pseudostem and leaf lamina) were evaluated for their relative phytotoxicity to some vegetable crops and rhizome extract showed the most inhibitory effect on lettuce seedling. Effects of banana plant extracts on seed germination and seedling growth of lettuce Banana plant extracts revealed a significant inhibition on seed germination and seedling growth of lettuce and the degree of inhibition increases with the increase of extract concentration. The absolute concentration (100%) extract showed the strongest inhibition (only 74.1% germination) of germination whilst the maximum percentage (95.8%) of germination was recorded from distilled water control at 72 hours after seed sown. The similar results were found by Chandra and Kandasamy (1997). They applied root extracts of Cyperus rotundus on onion and radish, and observed their inhibition effects on germination of the test crops. Besides, Lee et al. (1996) used root exudates of Capsicum annuum on lettuce and reported germination percentage of lettuce was reduced. Length of radicle of lettuce seedlings in control treatment (distilled water) was about 39 mm. While, absolute (100%) concentrated extract had significantly inhibited the radicle s (3.3 mm, 17.3 mm, 25.6 mm and 16.1 mm for extracts from rhizome, root, leaf sheath and leaf lamina, respectively) (Table 1). Considering the inhibitory point of view, strongest inhibition of 91.5, 55.8, 34.5 and 58.7% were recorded in 100% concentration of the extracts from rhizome, root, pseudostem and leaf lamina extracts, respectively, followed by 50% concentration of the extract. The lowest percent of inhibition (17.8, 13.5, 2.3 and 15.6) were found in the 15% of each type of extract. This result indicates that extract from rhizome was the strongest inhibitor than that from any other extracts. Similar pattern of inhibition was evident in case of plumule growth of lettuce (Table 1). Rhizome extract strongly delayed and inhibited the germination of lettuce (74.1%) at 72 hrs over control or compared to other extracts. It also strongly inhibited radicle of lettuce (91.5%) compared to root (55.8%), pseudostem (34.5%) and leaf lamina extract (58.7%), respectively, although the dry matter content and concentration of rhizome extract were similar to other parts or less than leaf lamina extract (Fig. 1 & 2). Thus, the results revealed that the rhizome extract showed more pronounced inhibition on germination and seedling growth of lettuce. Irrespective of nature of extracts radicle growth of lettuce was more inhibited than the plumule because the former was in direct contact with the extract than the latter. So, rhizome extract was chosen to observe its effect on other vegetable crops in the subsequent experiments.

4 238 BANANA PLANT EXTRACTS AND VEGETABLE SEEDS Table 1. Effects of extracts from different parts of banana plant on seed germination and seedling growth of lettuce Treatments (banana plant extracts) Rhizome extract Root extract Pseudostem (leaf sheath) extract Leaf lamina extract Germination growth growth 24 hrs 72 hrs Control 92.5 a 95.8 a 39.2 a a 0 15 % 90.8 ab 95.8 a 32.2 b b % 86.6 ab 90.0 b 25.4 c c % 78.3 b 85.0 b 15.3 d d % 39.1 c 74.1 c 3.3 e e 50.7 Control 90.8 a 98.3 a 39.2 a a 0 15 % 87.5 a 93.3 ab 33.9 b b % 88.3 a 91.6 abc 32.1 c c % 85.8 a 89.1 bc 27.4 d d % 79.1 b 85.8 c 17.3 e e 34.5 Control 95.8 a 99.1 a 39.1 a a 0 15 % 95.0 a 98.3 a 38.2 ab b % 90.8 ab 94.1 b 36.3 b b % 83.3 b 95.0 b 34.3 cd c % 80.8 c 90.0 c 25.6 e d 31.6 Control 93.3 a 98.3 a 39.0 a a 0 15 % 89.1 b 92.5 b 32.9 b b % 85.0 c 89.1 bc 25.9 c c % 80.0 d 87.5 cd 22.7 d c % 78.3 d 84.1 d 16.1 e d 41.5 The figures in a column having the similar letter (s) do not differ significantly as per DMRT at 5% level of significance. Experiment 2 Rhizome extracts were selected for further experiment to observe its effect on germination percentage, radicle and plumule growth of radish, red amaranth, amaranth, cucumber, ribbed gourd, bean and okra.

5 ROY et al Dry matter (g) Rhizome Root Pseudostem Leaf lamina Different parts of banana plants Fig. 1 Amount of dry matter in the fresh parts (100 g each) of banana plant used for the experiment (each value is the average of three replications) Concentration of extracts Rhizome Root Pseudostem Leaf lamina Different parts of banana plants Fig. 2 Actual concentration of the extracts (before dilution) extracted from different parts of banana plants (each value is the average of three replications)

6 240 BANANA PLANT EXTRACTS AND VEGETABLE SEEDS Effect of rhizome extracts on seed germination of some vegetable crops The effects of rhizome extracts on seed germination of radish, red amaranth, amaranth, cucumber, ribbed gourd, bean and okra were found to be significant (Table 2). Results showed that germination percentage decreased with increasing concentration of rhizome extract. Control showed the highest germination percentage (86.6 and 95.8, 85.0 and 96.6, 80 and 96.6, 89.1 and 100, 48.3 and 95, 76.6 and 95.8, and 77.5 and 91.6% in case of radish, red amaranth, amaranth, cucumber, ribbed gourd, bean and okra, respectively at 24 and 72 hours), followed by 15% rhizome extract. In contrast, absolute extracts (100%) showed the lowest germination percentage (38.3 and 66.6, 53.3 and 63.3, 42.5 and 50.8, 57.5 and 76.6, 30.0 and 51.6, 52.5 and 60.8, and 55.0 and 60.0% in case of radish, red amaranth, amaranth, cucumber, ribbed gourd, bean and okra at 24 hrs and 72 hrs, respectively). Initially at 24 hours the vegetable seeds showed slow rate of germination compared to later stage at 72 hours. It can be concluded that the germination was delayed and significantly inhibited in all the vegetable crops with increasing concentration of rhizome extract. Radish, amaranth and ribbed gourd was more responsive to the rhizome extract than the other vegetable crops. Effects of rhizome extracts on radicle of some vegetable crops The result revealed that radicle of the test crops declined with increasing the concentration of rhizome extract (Table 3). However, the most inhibitory effects of rhizome extract on radish, red amaranth, amaranth, cucumber, ribbed gourd, bean and okra (62.4, 87.4, 78.7, 79.4, 82.1, 59.9 and 72.5%, respectively) were found in absolute (100%) concentration of the extract whilst the least (5.5, 21.0, 27.7, 15.8, 40.6, 20.4 and 17.4%, respectively) were found in 15% of the extract concentration. It is evident that rhizome extracts showed more pronounced inhibitory effect on radicle growth than that of plumule growth as the radicle remain direct contact with the extract solution. Effects of rhizome extracts on plumule of some vegetable crops Although plumule growth of the vegetable crops responded differently, the regular pattern of inhibition was evident i.e., inhibition increased with the increase of concentration of rhizome extract. Control plants showed the highest plumule while the lowest was found in 100% concentrated extract (Table 4). Thus, the most inhibition of the vegetable crops plumule (28.5, 50.5, 52.3, 67.0, 70.1, 72.5 and 75.9% in case of radish, red amaranth, amaranth, cucumber, ribbed gourd, bean and okra, respectively) was evident for absolute (100%) concentration of rhizome extracts. The aforesaid results lead to the conclusion that among the studied extracts (rhizome, root, pseudostem and leaf lamina), rhizome extract had shown the strongest inhibitory effects on germination and seedling growth of the test plants. Different concentrations of the diluted extracts of banana plants also showed significant inhibition on seedling growth of all studied vegetable crops and the inhibition was concentration dependent. The response of the test plant species to the rhizome extract varied differently and the lettuce seedlings were found most sensitive.

7 ROY et al Table 2. Effects of rhizome extracts from banana plants at different concentration on the seed germination of some vegetable crops at 24 hrs and 72 hrs after sowing Treatment (rhizome extracts) Radish Red amaranth Amaranth Cucumber Ribbed gourd Bean Okra 24 hrs 72 hrs 24 hrs 72 hrs 24 hrs 72 hrs 24 hrs 72 hrs 24 hrs 72 hrs 24 hrs 72 hrs 24 hrs 72 hrs Control 86.6 a 95.8 a 85.0a 96.6a 80.0 a 96.6 a 89.1 a a 48.3 a 95.0 a 76.6 a 95.8 a 77.5 a 91.6 a 15 % 80.0 ab 82.5 b 70.8b 78.3b 70.0 ab 79.1 b 75.0 b 92.5 ab 46.6 ab 67.5 b 64.1 b 78.3 b 68.3 b 74.1 b 25 % 70.8 bc 83.3 b 64.1c 75.0b 61.6 b 74.1 bc 68.3 c 90.0 b 45.1 b 61.6 c 60.8 bc 73.3 c 64.1 bc 70.8 b 50 % 61.6 c 75.0 bc 61.6c 68.3c 59.1 b 66.6 c 60.8 d 84.1 bc 40.8 b 55.8 d 58.3 c 67.5 d 61.6 c 65.8 c 100 % 38.3 d 66.6 c 53.3d 63.3d 42.5 c 50.8 d 57.5 d 76.6 c 30.0 c 51.6 d 52.5 d 68.8 e 55.0 d 60.0 d The figures in a column having the similar letter (s) do not differ significantly as per DMRT at 5% level of significance. Table 3. Inhibitory effects of different concentration of rhizome extracts from banana plant on the radicle of some vegetable crops at four days after sowing Treatment (rhizome extracts) Radish Red amaranth Amaranth Cucumber Ribbed gourd Bean Okra Control 72.2 a a a a a a a 0 15 % 68.2 b b b b b b b % 56.8 c c c c c c c % 42.6 d d d d d d d % 27.1 e e e e e e e 72.5 The figures in a column having the similar letter (s) do not differ significantly as per DMRT at 5% level of significance. Table 4. effects of rhizome extracts from banana plants at different concentrations on the plumule of some vegetable crops at four days after sowing Treatment (rhizome extracts) Radish Red amaranth Amaranth Cucumber Ribbed gourd Bean Okra Control 65.2 a b b a a a a 0 15 % 62.8 ab a a a b b b % 61.0 b c c a c c b % 55.2 c d d b d c c % 46.6 d e e c e e d 75.9 The figures in a column having the similar letter (s) do not differ significantly as per DMRT at 5% level of significance. 241

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