Screening of coconut (Cocos nusifera L.) for drought tolerance

Drought causes a substantial reduction in national yield of coconut and also a loss of coconut palms in severe droughts thus resulting in serious economic consequences in the coconut industry in Sri Lanka. Therefore, it is a prime importance to identify some putative drought tolerant genotypes for the use in drought prone areas. The long generation and maturation periods of coconut restrict the selection of genotypes based on yield. Therefore, in this study the effects of drought on stomatal conductance (gs) and water potential (Ø) of four coconut genotypes (the accession Clovis [CL] is believed to be tolerant to drought while the rest Dwarf Green [DG], Dwarf Brown [DB] and Cameron Red Dwarf [CRD] are sensitive) were measured to develop an index for stomatal performances (ISP) using ISP = åtx=1 X. FX equation. Where, t, X and F are the number of genotypes, grade point obtained by the genotype for recordings of gs and Ø during drought and frequency of the corresponding grade point respectively. All palms were about 15 years of age and managed according to the recommended practices, in adjacent plots at the Potthkkulama Research Station, in IL1 Agro-Ecological Region. Eight adjacent palms from each of four genotypes were selected. Palms were monitored throughout the 80-day natural drought experienced in early 2005. DB showed the highest ISP (24) while DG (22.5) and CL (21.5) were next with minor differences and CRD (19), being the lowest of all. Thus, CRD can be identified as a drought sensitive genotype compared to the rest. Therefore, four genotypes can be ranked according to drought tolerance in terms of ISP as DB>DG>CL>CRD. However, these results are substantially different from known conditions at the field level. Therefore, more careful observations on much harsher and prolonged drought are needed to verify the applicability of this method.

W G D Lakmini1, N P A D Nainanayake2 and W A J M De Costa3
1Department of Crop Science, University of Ruhuna, Sri Lanka
2Plant Physiology Division, Coconut Research Institute of Sri Lank

Evaluation of Luffa (Luffa acutangula (L.) Roxb) varieties under low country intermediate zone of Sri Lanka

Luffa (Luffa acutangula) is a popular low country vegetable in Sri Lanka and it is one of the most highly utilized vegetable species in the farming systems of dry and intermediate zones. The existing Luffa varieties in Sri Lanka, recommended by the Department of Agriculture, and the introduced hybrids are vulnerable to pests and diseases and the cost for pest control mainly accounts for the higher production cost of Luffa. Makandura Selection (MK) is a Luffa variety selected from farmer fields and it shows tolerance to fruit fly (Bactrocera cucurbitae (Coquillett)), which is the most serious pest causing high level of economic losses. Therefore, an experiment was conducted at the Regional Agricultural Research and Development Centre, Makandura, to evaluate the performance of Makandura Selection along with the two Department of Agriculture recommended Luffa varieties, Asiri and LA 33. The experiment was laid out in a randomized complete block design with four replicates. Evaluation was done based on reproductive, yield and fruit quality parameters. Though the variety LA 33 recorded the significantly highest yield (9.08 t/ha), the higher fruit length (35.02 cm), higher fruit weight (280.5 g) and high fruit firmness (4.38 kg) were not desirable in the context of consumer preference. The variety Asiri recorded a significantly lower yield (7.05 t ha-1) and the lowest fruit firmness (3.89 kg) which are not preferred by the farmers. The variety Makandura Selection showed moderate yields (8.98 t ha-1) and better performance in fruit quality attributes such as lower fruit length (21.7 cm), lower fruit weight (207.2 g) and moderate firmness (4.25 kg). Therefore, the fruit fly tolerant ability, along with these positive fruit characteristics makes Makandura Selection a suitable variety to introduce to the Luffa growers in Sri Lanka after further testing.

R M S S Rajapaksha1, K P D Siriwardana2 and R H M K Ratnayake
Department of Horticulture and Landscape Gardening, Wayamba University of Sri Lanka, Sri Lanka.
Regional Agriculture Research and Development Center (RARDC), Makandura,
Sri Lanka.

Exploring natural resources for sustainable management of ecosystems: future challenges for control and management of Xyleborus fornicatus eichh. (Coleoptera: Scolytidae), the shot-hole borer of tea in Sri Lanka

In view of the highly diverse genetic base of the seedling tea plants, though cultivated as a monocrop, along with shade trees and surrounding forests, provided a reasonably stable ecosystem then. With the introduction of high yielding vegetatively propagated tea during 1950’s, a significant change in the distribution and population densities of pests has been taken place. Shot-hole borer is one such pest and since then it has become the most serious and damaging pest of tea in Sri Lanka. Control has been a difficult task as a result of its’ wide distribution from near sea level up to 1500m amsl and the concealed habit virtually protected from parasites and predators. Biological control using entomopathogenic fungus, Beauvaria bassiana Vuillemin (Balsomo) is being viewed as an environmentally friendly alternative to chemical control in the light of growing concern on the usage of pesticides and since of late, the detection of pesticide residues in made tea. Preliminary investigations were carried out with a view to find out a suitable local strain/s of the fungus for use against this pest.

Laboratory studies have shown that strains of this fungus isolated from a tea garden in Talawakelle (Nuwera Eliya District) and a home garden in Welimada (Badulla District) are highly pathogenic to shot-hole borer imparting more than 90% mortality. A potential exists for using the locally available natural resources like entomopathogenic fungi for the management of key pests in a compatible and ecologically acceptable manner. This forms the basis for Integrated Pest Management (IPM) approach of key pests. These efforts will promote and ensure the sustainable development of the tea ecosystem.

R S Walgama, P Senanayake and C De Seram
Division of Entomology, Tea Research Institute, Talawakelle, Sri Lanka.

Development of new cultivation technology for straw mushroom (Volvariella

Paddy straw mushroom (Volvariella volvacea) is an edible mushroom variety which can be cultivated under tropical and sub tropical conditions. In Sri Lanka, though the majority of farmers grow oyster mushroom they are willing to undertake other mushroom types, including straw mushroom and milky mushroom. Straw mushroom cultivation is highly rewarding because of the favourable climatic conditions in Sri Lanka and the abundant availability of raw materials. The existing outdoor method for straw mushroom cultivation introduced by the Department of Agriculture (DOA) gives low or/and irregular yield. As the optimum environmental conditions are crucial in straw mushroom production, an indoor cultivation method using a polythene house was tested with the existing outdoor method. Cotton waste and paddy straw were used as the growing media in both outdoor and indoor conditions under four treatments viz. paddy straw compost in polythene house (T1), cotton waste compost in polythene house (T2), paddy straw in outdoor environment (T3) and cotton waste in outdoor environment (T4), arranged in a Completely Randomized Design with three replicates. The results revealed that,the indoor cultivation method with cotton waste compost substrate (T1) gave significantly higher values for average yield (6901.18 kg/ha) and average marketable yield (6489 kg/ha) compared to other treatments. Outdoor culture in straw substrate (T3) resulted lowest values for the same yield parameters (567.13 kg/ha, 516.31 kg/ha, respectively). Indoor cultivation method with paddy straw compost and cotton waste compost both resulted higher yields when compared to the outdoor culture. As paddy straw is freely available in Sri Lanka, combining of paddy straw compost and cotton waste compost as the substrate for straw mushroom culture under indoor conditions would be more profitable.

A S Nissanka1, P Rajapakshe2 and R H M K Ratnayake1
1Department of Horticulture and Landscape Gardening, Wayamba University of Sri Lanka, Sri Lanka
2Regional Agricultural Research and Development Centre, Gonawila, Sri Lanka

In vitro multiplication of Wthnia somnifera auxiliary buds for mass propagation

Wthnia somnifera of family Solanaceae commonly known as Amukkara or Ashwaganda is an important medicinal perennial herb with long tapering roots. The roots are widely used in ayurvedic medicine and prescribed for hiccup, female disorders, cough and rheumatism. Wild and cultivated forms are available and cultivated plants differ in morphological and therapeutical action from wild ones. The annual requirement of 42347 kg is imported from India spending Rs. 2, 840, 449 (IUCN , 2005). Development of a method for in vitro mass production of this valuable species would substantially reduce the import cost and generate employment opportunities. This study was conducted to develop an in vitro protocol for mass production of W. somnifera.

In vitro grown seedlings of W. somnifera were used to excise single nodal cuttings and cultured on MS (Murashige & Skoog, 1962) medium. The effect of NAA (0, 0.1, 0.2 mg/l) in combination with BAP (0.5, 1.0, 1.5 mg/l) on shoot proliferation was tested in solid and liquid MS media containing two levels of sucrose (3% and 4%). Proliferation (number of plantlets produced) was observed at weekly intervals.

Highest shoot proliferation rate (1: 20) was observed in solid MS medium containing 3% sucrose and 1.5mg/l BAP after two months. In solid MS medium with 4% sucrose and 1.0 mg/l BAP 1: 10 shoot proliferation rate was observed after two months. During the same time period 1:15 shoot proliferation rate was observed in solid MS medium with 3% sucrose, 0.5 mg/l BAP and 0.2 mg/l NAA, where 1: 12 proliferation rate was observed when BAP concentration increased up to 1.0 mg/l. Solid MS media both with 3% and 4% sucrose levels and 0.5 mg/l BAP showed some proliferated shoots while other solid cultures were not proliferated. However cultures containing NAA in addition to BAP enhance rooting of proliferated shoots before transferring the separated shoots to rooting media. The explants in liquid MS medium with 4% sucrose and 1.0 mg/l BAP, proliferation initiated in one week and gave 1:40 shoot multiplication rate after two months. Rest of the liquid cultures with different BAP and NAA combinations were not proliferated within the same time duration.

Finally it can be concluded that highest shoot proliferation of W. somnifera through single nodal cuttings can be obtained on liquid MS medium with 4% sucrose and 1.0 mg/l BAP.

P S Warakagoda, D L C Kumari and S Subasinghe
Department of Crop Science, Faculty of Agriculture, University of Ruhuna, Sri Lanka займы на карту

Effect of physiological status on rooting of Masbedda (Gymnema sylvestre) cuttings

Vegetative propagation by means of cuttings is an important method for starting new plants identical to the parent plants. Many plants can be propagated with good results by cutting, though the success depends upon the propagator’s circumstances, the time of year, and the plant to be propagated. The present study was carried out to investigate the effect of physiological stage on rooting of Gymnema sylvestre stem cuttings.

Healthy, double nodded cuttings were made from the mature plant stock established at the Faculty of Agriculture, University of Ruhuna. The cuttings taken from pre-flowering (T1), flowering (T2) and post-flowering (T3) stages were stuck into preformed holes in poly bags filled with moistened rooting medium which consisted of sand, top soil and compost (1:1:1 by volume). They were placed in a shade house and watered once a day. The Completely Randomized Design (CRD) was used with ten replicates. Assessment was done 75 days after for rooting. The percentage survival was not significantly (p £ 0.05) different between cuttings taken from the pre-flowering (92%) and post-flowering (87%) stages. No significant (p £ 0.05) differences also in the percentage of callused and rooted cuttings were recorded between T1 and T3. However, number of roots and length of the longest root per cutting were significantly (p £ 0.05) higher in T1 than any other. Furthermore, T2 showed the lowest figures for all the parameters assessed, indicating that the physiological status of the stock plant at the time the cuttings are excised is of great importance for the rooting process.

K K I U Arunakumara1, U Wickramasinghe1, B C Walpola2 and S Subasinghe1
1Department of Crop Science, University of Ruhuna, Kamburupitiya.
2Department of Soil Science, University of Ruhuna, Kamburupitiya. займ без отказа

In vitro propagation of Kaempferia galanga (L)

Kaempferia galanga (L) is an aromatic perennial herb, which is widely used in Ayurvedic medicine. Dry tubers are imported in large scale to Sri Lanka due to lack of mass production in Sri Lanka. Disease susceptibility and higher cost of production have restricted its cultivation. Propagation of Kaempferia galanga is normally by rhizome cuttings but disease susceptibility of tender rhizomes restricts propagation in large scale. Propagation through other vegetative methods is not possible. Rahman et al. (2004) reported the possibility of obtaining plants through somatic embryogenesis but the survival rate was low. Therefore an attempt was made to develop a protocol for mass propagation of Kaempferia galanga through direct organogenesis. Leaf discs and axillary buds were used as explants. Axillary buds isolated from rhizomes of Kaempferia galanga mother plants were sprayed with 0.2% Captanä 2-3 days before collection. After that, they were placed on a wet paper lined tray and covered again with another wet paper. Five to six days later young axillary buds were emerged from nodes and they were used as explants. For leaf disc explants leaves were washed with soap and soaked in a solution of Teepolä for 15 minutes, and washed with running tap water for 45 minutes.

Both leaf discs and axillury buds were dipped in 5% Chloroxä (5.25% Sodium hyperclorite v/v) for 10-15 minutes under sterile conditions. Then they were washed 10% Cloroxä for 3 minutes and 70% ethanol for one minute each followed by two successive washings in sterile distilled water. Explants were cultured on MS basal medium (Murashige and Skoog, 1962) supplemented with different concentrations of Benzyl amino purine (BAP) and Indole acetic acid (IAA) (2.00 mgl-1 – 2.25 mgl-1 and 0.30 mgl-1 – 0.70 mgl-1 respectively). Sucrose 3% (w/v) and 0.8% agar were added to the media. pH was adjusted to 5.8.

Cultures were incubated under 16 hr light /8 hr dark at 26 + 1 0C temperature for 21 days. Callusing was not observed from both tested explants in any of the media tested. After 15 –18 days of incubation axillary buds were elongated in all combinations tested. MS supplemented with 2.25 mgl-1 BAP and 0.5 mgl-1 IAA showed the highest elongation (490 ± 10 mm). After 25-30 days of incubation in vitro grown shoots were cut and separated from the explant. Then they were subcultured on the same medium and incubated in 16 hr light at 26 + 1 0C temperature for shoot multiplication. MS medium was used as basal medium with above combinations of growth regulators.

The highest multiplication was observed in 2.25 mgl-1 BAP and 0.5 mg-1 IAA (7.0 + 0.02) shoots per explant. Further sub culturing on to the same medium induced roots. Seven-weeks old plantlets were removed from culture vessels, washed well to remove all agar and transferred to small plastic pots containing sand, soil and compost in 1:1:1 proportion by volume and kept in shade house covered with polythene bags, for acclimatization. 100% survival was observed when acclimatized plants were transferred to the field.

 K M R T Wijekoon and W T P S K Senarath
Department of Botany, University of Sri Jayewardenepura, Sri Lanka кредит онлайн

Collection, conservation, evaluation and use of durian germplasm at Horana

Unavailability of high quality varieties is one of the constraints in commercial durian production. A program to collect durian germplasm was initiated at Horana. Fruits from 26 seedling trees were evaluated for fruit weight, number of arils, number of seeds, weight of husk and seeds using six fruit per tree. Aril size, seed size, % rind, % seed and % aril were calculated. Aril color, flavor and overall acceptability were also recorded with a panel test. Results showed high variability in fruit quality traits exists among trees. Highest variability was found in number of seeds per fruit (CV=36.2%) while % rind showed the lowest variability (CV=7.26%). Number of seeds varied from 3.7 -19.2 per fruit while % rind varied from 60.5-79.5%. Nine accessions selected were planted with five replicates for further evaluation. Plant height and stem girth showed significant differences at early stages but became non significant by three years after planting. At 42 months after planting plant height varied from 368-492 cm while stem girth ranged from 42.0 – 52.8 cm. Principal component analysis of selected fruit and leaf characteristics of six accessions showed that first three PCs accounted for 89.35% of the variation in the characteristics used for the analysis indicating that the varieties of the collection are diverse. Collection of germplasm continued with establishment of a field gene bank to conserve accessions with two replicates. Nine selections were also further tested in farmer fields for adaptability.

K H S Peiris
Fruit Crops Research and Development Center, Department of Agriculture, Kananwila, Horana взять деньги в долг на карту

In vitro callus induction of Spilanthes calva DC [Spilanthes acmella auct. nonL,.] (Maha Akmella)

Spilanthes calva DC. (Maha Akmella) is a valuable medicinal plant belongs to Family Asteraceae. It is widely used in indigenous medicine to treat toothache in most of the Asian countries. Not only it has anesthetic properties, but also contain secondary metabolites, with the insecticidal properties, which could be used as potential bio insecticide. This is an annual plant, which grows to a height about 30 cm. After flowering mother plant is dried off. Four to six weeks later seeds are germinated and new seedlings are produced. Viability of seeds loses within short period of time. Even though seeds are germinated percentage of germination is low (about 30%). Rooting of cuttings is also not possible. This is a limitation in using this valuable medicinal plant for commercial production. Therefore it is very important to develop a protocol for mass propagation through tissue culture and establishing cell cultures will be useful for large-scale chemical extraction in industrial purposes.

Leaf discs were used as explant for callus initiation. In order to identify the suitable maturity stage for callus initiation, leaves were harvested at different maturity stages i.e first, second and third fully opened leaf.

Leaves were washed with Dettolä soap and soaked in a solution of Teepolä for 5 minutes. After that leaves were washed with running tap water for 45 minutes. In order to surface sterilize. Leaves were washed with 10% Cloroxä (5.25% Sodium hypochlorite v/v) for 5 minutes and then with 70% alcohol for 30 seconds each followed by three successive washings in sterile distilled water. These operations were carried out inside the laminar airflow cabinet before inoculation. Basal media tested for the study were full strength MS (Murashige and Skoog, 1962) medium and ½ MS (both macro and micronutrients) medium. Media were supplemented with different concentrations (1.0 mgl-1 – 3.0 mgl-1) of BAP and 2,4-D. Cultures were incubated under complete dark at 25±1°C in the growth room.

Study conducted by Haw and Keng (2003) on the same species produced multiple shoots from axillary bud explants without inducing callus in MS medium supplemented with 2.0 mgL-1 BAP. In the present study, callusing was observed within 5 days of incubation in full strength MS medium supplemented with BAP and 2,4D. It took longer period to initiate callus when both macro and micro nutrients in the basal medium was lowered to half and the amount of callus produced was also very low even after 6th week of incubation. In order to observe the time taken to produce maximum amount callus fresh weight was measured after 2nd, 4th and 6th week of incubation. It was observed that maximum amount of callus was produced within 4 weeks in all explant types tested with a maximum of 0.88 g ± 0.23 in leaf discs obtained from first fully opened leaf.

In order to determine the best growth regulator combination for callus initiation, calli fresh weights were measured after fourth week of incubation in different growth regulator combinations tested. Highest amount of calli were in MS medium in the presence of 2.25 mgl-1 BAP and 1.0 mgl-1 2,4-D. Fragile calli, which were transulant and mucilaginous in nature were observed within 15 days of incubation, which could lead to cell suspension cultures. заём

In vitro callus induction of Spilanthes calva DC [Spilanthes acmella auct. nonL,.] (Maha Akmella)

Spilanthes calva DC. (Maha Akmella) is a valuable medicinal plant belongs to Family Asteraceae. It is widely used in indigenous medicine to treat toothache in most of the Asian countries. Not only it has anesthetic properties, but also contain secondary metabolites, with the insecticidal properties, which could be used as potential bio insecticide. This is an annual plant, which grows to a height about 30 cm. After flowering mother plant is dried off. Four to six weeks later seeds are germinated and new seedlings are produced. Viability of seeds loses within short period of time. Even though seeds are germinated percentage of germination is low (about 30%). Rooting of cuttings is also not possible. This is a limitation in using this valuable medicinal plant for commercial production. Therefore it is very important to develop a protocol for mass propagation through tissue culture and establishing cell cultures will be useful for large-scale chemical extraction in industrial purposes.

Leaf discs were used as explant for callus initiation. In order to identify the suitable maturity stage for callus initiation, leaves were harvested at different maturity stages i.e first, second and third fully opened leaf.

Leaves were washed with Dettolä soap and soaked in a solution of Teepolä for 5 minutes. After that leaves were washed with running tap water for 45 minutes. In order to surface sterilize. Leaves were washed with 10% Cloroxä (5.25% Sodium hypochlorite v/v) for 5 minutes and then with 70% alcohol for 30 seconds each followed by three successive washings in sterile distilled water. These operations were carried out inside the laminar airflow cabinet before inoculation. Basal media tested for the study were full strength MS (Murashige and Skoog, 1962) medium and ½ MS (both macro and micronutrients) medium. Media were supplemented with different concentrations (1.0 mgl-1 – 3.0 mgl-1) of BAP and 2,4-D. Cultures were incubated under complete dark at 25±1°C in the growth room.

Study conducted by Haw and Keng (2003) on the same species produced multiple shoots from axillary bud explants without inducing callus in MS medium supplemented with 2.0 mgL-1 BAP. In the present study, callusing was observed within 5 days of incubation in full strength MS medium supplemented with BAP and 2,4D. It took longer period to initiate callus when both macro and micro nutrients in the basal medium was lowered to half and the amount of callus produced was also very low even after 6th week of incubation. In order to observe the time taken to produce maximum amount callus fresh weight was measured after 2nd, 4th and 6th week of incubation. It was observed that maximum amount of callus was produced within 4 weeks in all explant types tested with a maximum of 0.88 g ± 0.23 in leaf discs obtained from first fully opened leaf.

In order to determine the best growth regulator combination for callus initiation, calli fresh weights were measured after fourth week of incubation in different growth regulator combinations tested. Highest amount of calli were in MS medium in the presence of 2.25 mgl-1 BAP and 1.0 mgl-1 2,4-D. Fragile calli, which were transulant and mucilaginous in nature were observed within 15 days of incubation, which could lead to cell suspension cultures.

 S Hewage and W T P S K Senarath
Department of Botany, University of Sri Jayewardenepura, Sri Lanka. срочный займ без проверок