Annals of the Sri Lanka Department of Agriculture. 2008.10:73-80.
POTENTIAL OF ROOTED SUCKERS OF HYBRID TOMATO (Lycopersicon esculentum MILL.) UNDER PROTECTED CULTURE K.M.S. KODIKARA1, K.P. SOMACHANDRA1 and S.M. WIJESUNDERA2 1 Regional Agricultural Research and Development Centre, Diyathalawa Road, Bandarawela 2 Ministry of Agriculture Development and Agrarian Services, “Govijana Mandiraya�, Rajamalwatte Avenue, Battaramulla
ABSTRACT Protected agriculture is becoming increasingly popular among vegetable and flower growers in the Up Country Intermediate Zone in Sri Lanka. Tomato is the most popular vegetable crop due to high market demand for high quality fruits and ability of growing throughout the off season. To achieve the above targets, farmers should select appropriate varieties. Although the above characters are found in imported hybrid varieties which are suitable for protected culture, high cost and unavailability of seeds cause problems for growers. Therefore, a study was conducted in a protected house at the Regional Agricultural Research and Development Centre (RARDC), Bandarawela during the year 2006 to identify alternative planting material for hybrid tomatoes. This research included two studies viz. identification of suitable rooting medium for sucker establishment and comparison of rooted suckers and seedlings for their yield and plant growth. Six different rooting media based on coir dust and sub soil were evaluated for establishment, shoot length, root length and number of roots. It was found that coir dust : compost : river sand (2:1:1) showed the highest establishment over 98% and significantly higher number of roots (32.33) and length (78.30 mm). In the second study, rooted suckers were compared with seedlings for plant growth and yield parameters including plant height, number of flower clusters per plant, number of flowers per cluster, number of fruits per plant, total yield per plant and average weight of fruit. The results did not show a significant difference between seedlings and rooted suckers. KEYWORDS: Hybrid tomato, Planting materials, Protected agriculture, Rooting media, Rooted suckers.
INTRODUCTION Protected Agriculture or Controlled Environment Agriculture (CEA) for vegetable production attracts interest from the farmers in Sri Lanka. CEA has been practiced to produce cut flowers and ornamental plants during past three decades. However, vegetable production in CEA commenced during late 1990s (Perera, 2002). The financial and technical support given by the government sector as well as private institutes encourage farmers to practice CEA. As a result of these efforts, nearly 120 greenhouses had been established in the Badulla district during 1997-1998 period (Weerakkody et al., 2001; Perera, 2002). Weerakkody et al. (2001) and Perera (2002) reported that, the main vegetables cultivated in this system in the Badulla district are
74 KODIKARA et al.
hybrid varieties of bell pepper, tomato, and salad cucumber, while small extent is under lettuce, cauliflower, strawberry, musk melon etc,.
ROOTED SUCKERS IN HYBRID TOMATO 75
Tomato is the most popular vegetable grown under this system in Sri Lanka (Wahundeniya et al., 2006), due to its high market demand. One of the main issues related to tomato cultivation in Sri Lanka is seeds. Perera (2002) reported that majority of the CEA farmers use high cost hybrid seeds. He further mentioned that scarcity of high quality seeds, higher price and disorganized seed supply were the main constraints faced by the farmers in obtaining seeds. Weerakkody et al. (2001) stated that most of the extension officers agreed with the fact that planting materials are not available in time. Farmers invest reasonable sums of money to construct a protected structure to initiate the CEA, and resource poor farmers are unable to spend more money to purchase seeds and fertilizer to cultivate the crops inside these structures. It is not possible to produce seeds of hybrid varieties and they have to depend solely on imported seeds. The propagation of plants is either sexual or asexual. Asexual propagation by stem cuttings has been used in many plant species (Edmond et al., 1975). The asexual propagation of the plant will provide a system of maintaining a selected clone or progeny from hybridization without fear of segregation, as there is no further recombination of genes (Toogood, 1980). Tomato (Lycopersicon esculentum Mill.) is mainly propagated by seeds. However, stem cuttings, tissue culture (Sabongari and Aliero, 2004) and grafting (Ilankoon et al., 2001) are the other alternatives to produce tomato. Nevertheless, the published information on vegetative propagation through stem cuttings of tomato is very scarce in Sri Lanka. It is well understood that single stem pruning is the standard practice in tomato production in greenhouses. The farmers have to remove all lateral branches (suckers) regularly to maintain the single stem. Hence, if there is a possibility of using these suckers to produce transplants of tomato, it will be an immense benefit for the resource poor farmers to reduce their cost of cultivation as well as a solution for problems faced by CEA farmers with planting materials. This study was therefore undertaken to determine the possibility of using tomato suckers as alternative planting materials for seeds and the influence of different rooting media, based in sub soil and coir dust, on the rooting and growth of tomato suckers. The specific objectives were to identify the best medium for establishment of tomato suckers and to select a substitute for high cost hybrid seeds. MATERIALS AND METHODS Two experiments were carried out during the year 2006 at the Regional Agricultural Research and Development Centre (RARDC), Bandarawela. The experiments were set up in a 75 m2 protected house
76 KODIKARA et al.
covered with insect proof netting and UV resistant polythene. The protected house had a top ventilated system and day temperature ranged between 27±8°C during day and 18±4°C during night. Two studies were conducted separately to identify a suitable rooting medium for the successful establishment of suckers and to compare the growth and yield potential of rooted suckers vs. seedlings. The hybrid tomato variety “volcano” was selected for the study due to it is high yielding ability and popularity as a CEA crop (Wahundeniya et al., 2006). Plant material The seeds of the selected variety were sown in the seedling trays which were filled with steam sterilized (at 80-100°C for 3 hrs.) coir dust and placed inside the greenhouse. Three weeks after germination the seedlings were transplanted in individual containers. Containers for transplants were prepared using black polythene (200 gauge) bags which were of 35 cm x 40 cm (W x H) in size, sealed at the bottom with 5 mm diameter holes (12 in each container) and punched at the basal one third of the bottom. These containers were filled with a mixture of steam sterilized coir dust and partially burned rice husk (2:1). The plants were maintained with the fertilizer given in (Table 1) for 3 months. Uniformly matured 6 cm high lateral branches emerged from 3-7 leaf nodes of the main stem were excised using a sterilized stainless steel sharp blade during the early hours in the day when the plants were turgid. These cuttings (lateral branches) were used, immediately after excision in all experiments. Table 1.
Quantity of fertilizer (Albert’s mixture, a complete commercial fertilizer mixture manufactured by CIC Pvt. Ltd.) and water applied during the cropping cycle.
Weeks after transplanting (WAT) 1-3 4-6 7-10 >10
Fertilizer (gms./plant/day) 0.4 0.75 1.0 1.5
Water (ml./plant/day) 150 200-250 400-500 500-750
Selection of suitable rooting medium Three coir dust based media and three soil based media, differing in composition, were evaluated for the selection of the most suitable medium for rooting of tomato cuttings. The media were formulated on volume ratios of Coir Dust (CD), Compost (CO), River Sand (RS) and Sub Soil (SS). The control treatment was only sub soil. The media included SS only, SS + CO (2:1), SS + CO + RS (2:1:1), CD only, CD + CO (2:1) and CD + CO + RS (2:1:1). The treatments were laid out in a Randomized Complete Block Design (RCBD) replicated three times. Twenty cuttings were used for a
ROOTED SUCKERS IN HYBRID TOMATO 77
treatment. The trial was established in styrofoam seedling trays filled with selected media and pre sterilized with steam (at 80-100°C for 3 hrs.). After establishment of cuttings, the trays were placed inside the protected house and maintained at field capacity, supplying a little water for first 3 days. Thereafter, a complete fertilizer mixture (Albert’s mixture, a commercial fertilizer mixture, manufactured by CIC Pvt. Ltd.) dissolved in water at the concentration of 1 g/l was supplied to the plants daily. Percentage of establishment, plant height, root length and number of roots per cutting were recorded twenty five days after transplanting. Comparison of rooted cuttings vs. seedlings Cuttings, obtained from the procedure mentioned above were used in this trial. These cuttings were established in nursery trays filled with the best medium selected from previous experiment. Seedlings were obtained in a nursery where they were established in seedling trays filled with steam sterilized coir dust. Cuttings and seeds were established at the same time and were maintained inside the protected house for 25 days. Seedlings and rooted cuttings were then transferred to individual containers, prepared using the procedure described in the plant material section. These containers were placed on a polythene sheet laid out on the greenhouse floor to avoid ground soil contamination. The transplants were arranged in RCBD in single rows with 60 cm inter row and 45 cm within row spacing to maintain a density of 3.7 plants/m2. The experiment was replicated 10 times. Plants were manually irrigated to maintain adequate water content in each container. Fertilizers were applied as shown in Table 1. Additionally, calcium and potassium nitrate were added at the rate of 4 and 2 g per plant respectively, once a week beginning from the 10th WAT. Electrical conductivity and pH of the nutrient solution was maintained between 3.25-4.5 mS/cm and 5.5-6.5 respectively. De-suckering was practiced 2 WAT and continued in 3-4 days intervals to maintain the single stem structure of the tomato plant. Suckers which emerged from leaf nodes were removed during the early hours of the day using disinfected stainless steel blades to avoid possible contamination and transmission of diseases. Vertical supports (stakes) were provided when transplants were 50 cm high (2 WAT). Early flowering was observed in transplants of rooted cuttings. However, these flowers were removed until the emergence of flowers in seedling transplants. Vegetative growth and yield parameters were evaluated. Plant height was measured from the soil level to apical bud at final harvest. Number of flower clusters per plant and number of flowers per cluster were recorded as reproductive growth parameters while number of fruits per plant, total and marketable fruit yield per plant and average fruit weight per plant were recorded as yield parameters.
78 KODIKARA et al.
RESULTS AND DISCUSSION Selection of suitable rooting medium It is important to mention that all the treatments based on sub soil showed poor performance than coir dust based mixtures. The data recorded in different treatments were analysed using Analysis of Variance (ANOVA) and the results are presented in Table 2. Table 2. Effect of rooting media on the establishment of cuttings (%), number of roots/plant, and root and shoot length. Rooting media
Establishment of No. of roots/ Root length Shoot cuttings (%) plant (mm) length (cm) SS only 40.66 d 09.33 e 39.33 c 6.70 c SS + CO (2:1) 55.33 c 15.33 d 40.66 c 7.03 c SS + CO + RS (2:1:1) 68.33 b 15.66 d 41.33 c 7.90 b b c b CD only 73.66 19.00 59.33 8.60 a b b b CD + CO (2:1) 82.66 23.66 61.66 9.00 a a a a CD + CO + RS (2:1:1) 98.67 32.33 78.33 9.10 a CV % 5.61 9.04 4.30 4.10 Values followed by same letter in each column are not significantly different at p=0.05, based on DMRT
Data recorded for the establishment of cuttings (%) showed that growth media had a significant effect on establishment. Mean values for establishment proved that CD + CO + RS was the most successful medium with 98.67% closely followed by CD + CO with 82.66% establishment, while lowest establishment (40.66%) was found in sub soil. Data pertaining to the number of roots per cutting is showed in Table 2. The ANOVA showed that media had significant effect on the number of roots per cutting. Means shows that maximum number of roots (32.33) was formed in CD + CO + RS followed by 23.66 in CD + CO, while minimum number of roots (9.33) were observed in the sub soil medium. The length of roots per plant was significantly affected by treatments. The means in Table 2 indicated that maximum root length of 78.33 mm was measured in CD + CO + RS medium. CD + CO and CD media performed similarly without significant difference among treatment means (61.66 mm and 59.33 mm respectively). The lowest root length (39.33 mm) was recorded in the medium containing sub soil only. In general, media based on sub soil showed poor performances with respect to each parameter. Nevertheless, mixing compost and river sand to the sub soil showed positive effect on observed parameters.
ROOTED SUCKERS IN HYBRID TOMATO 79
The recorded data revealed that cuttings laid on soil based media performed poorly with respect to all measured parameters compared to coir dust based media in rooting experiment. Among the CD based growth media, CD + CO + RS gave better results in terms of establishment (%), no. of roots per cutting, root and shoot length. The increased number and length of roots recorded in coir dust based media could be attributed to favourable environment created for root growth. Mayalagu (1983) and Mazeen (1999) reported that coir dust amended media has low bulk density, high porosity and low compactness. Coir dust has some advantages over other organic substrates such as low resistant to root penetration (Agbo and Omaliko, 2006). It was also observed that, coir dust improves absorption, infiltration and retention of water and thereby increase the root elongation (Mazeen, 1999). On the other hand organic matter (compost) would have helped to increase nutrient content and nutrient retention in the medium. Therefore, CD + CO medium performed better than only CD. Addition of sand into a medium increase weight per unit volume making it course textured and thereby increasing the water movement. The above physical improvement in a medium permits better proliferation of roots (Mayalagu, 1983). Increased number of roots and length facilitate the absorption of water and nutrient resulting in better establishment and more shoot growth. The high establishment (%) observed in coir dust based media may also be due to less consequences of rotting of cuttings by microbes. Mazeen (1999) also reported that addition of coir dust into a medium increase the CO2 production. CO2 enrichment at the surrounding atmosphere of a plant enhances shoot growth (Edmond et al., 1975). All these factors could attribute to the better performances of coir dust based media. It is also clear that addition of CO and RS further increased the establishment (%), number of roots, and root and shoot length. Lower establishment of suckers and comparatively low number of roots and root length observed in soil based media was probably due to lower porosity due to higher proportion of silt and clay. Lower porosity meant poorer aeration and it may be attributed to less number of roots per cutting and poor establishment. It also affects the root penetration. Comparison of rooted cuttings vs seedlings The rooted cuttings obtained from previous experiment were compared with seedling transplants for their growth and yield performances. Table 3 documents the growth and yield parameters obtained from plants produced using two different planting materials. Data revealed that plants of generative as well as vegetative origin had equal performance in terms of plant height, yield per plant and number of fruits per plant.
80 KODIKARA et al. Table 3. Growth and yield of rooted cuttings of tomato compared to the planting material of generative origin. Treatment Seedlings Rooted suckers CV% LSD
Plant height (cm) 238.00 224.50 4.3 ns
Av. No. of flowers per cluster 8.0 8.3 2.1 ns
Av. No of clusters per plant 11.7 11.7 2.7 ns
Fruit yield per plant (kg) 3.76 3.65 4.1 ns
No. of fruits per plant 56.5 54.3 5.1 ns
Average weight/ fruit (gm) 66.69 66.76 5.1 ns
Farmers who cultivate tomato in protected houses are mainly concerned about the per plant yield. Rooted suckers produce nearly 4.00 kg of fruits per plant. This yield is similar to the yield obtained by the farmers (Perera, 2002). Almost the same fruit yield was obtained in seedlings. The results clearly indicated that, there was no difference between seedlings and rooted suckers in all of the tested parameters. CONCLUSIONS Based on the results obtained from the two experiments, it appears that, tomato rooted suckers raised in CD+CO+RS (2:1:1) medium is a comparable alternative for seedlings, for production of hybrid tomato in protected systems. This will reduce the planting material cost and ensure the continuous cultivation of hybrid tomato in protected system rectifying the problem of scarcity of seeds. REFERENCES Agbo, C.U. and C.M. Omaliko. 2006. Initiation and growth of Gongronema latifolia Banth stem cuttings in different rooting media. African Journal of Biotechnology 5 (5):425-428. Edmond, J.B., T.L. Senn, F.S. Andrews and R.G. Halfacre. 1975. Fundamentals of horticulture, Fourth edition. McGraw-Hill Book Company, New York. USA. 198-206 p. Illankoon, J., I.J.De Zoysa and A. Wijesekera. 2001. Tomato grafting as a remedy for bacterial wilt in a protected agriculture system. Annals of the Sri Lanka Department of Agriculture 3:53-60. Mayalagu, K. 1983. Influence of different soil amendments on the physical properties of a heavy black soil and yield of groundnut TMV 7 in the Periyar-Vaigai command area. In The Madras Agricultural Journal. Eds. R. Jeyarajan. Pp 304-308. Agricultural University campus, Coimbatore, India. Mazeen, A.C.M., H.M.W. Herath and L.H.J. Van Holm. 1999. Use of coir dust as a soil amendment of growth and nitrogen fixation of Winged bean. Annals of the Sri Lanka Department of Agriculture 1:109-119.
ROOTED SUCKERS IN HYBRID TOMATO 81 Perera, T.H.C.S. 2002. Socio-economic aspects of controlled environment agriculture in Badulla district. Socio-Economics and Planning Centre, Department of Agriculture, Peradeniya. 5-25 p. Sabongari, S. and B.L. Aliero. 2004. Effect of soaking duration on germination and seedling growth of tomato (Lycopersicon esculentum Mill.). African Journal of Biotechnology 3 (1):47-51. Toogood, A. 1980. Propagation. J.M.Dent and Sons Ltd. London. 62 p. Wahundeniya, W.M.K.B., R. Ramanan, R.C. Wickramathunga and W.A.P. Weerakkody. 2006. Comparison of growth and yield performances of tomato (Lycopersicon esculentum Mill.) varieties under controlled environment conditions. Annals of the Sri Lanka Department of Agriculture 8:251-262. Weerakkody, W.A.P., L.H.P. Gunarathne and B.C.N. Peiris. 2001. Controlled Environmental Agriculture (CEA) in the Uva Province, Sri Lanka. Area based growth with equity programme. Department of Crop Science, Faculty of Agriculture, University of Peradeniya. 03-25 p.