Green Leaf Yield Research Articles

Efficacy of herbicides on weed control, rhizospheric micro-organisms, soil properties and leaf qualities in tea plantation

Field trials were conducted in Tarai region of Jalpaiguri, West Bengal, India (26°88 N latitude; 88°32 E longitude, and 122 m above mean sea level) under natural weed infestations in tea garden during 2017 and 2018 to evaluate the efficacy of herbicides on weed flora, non-target soil organisms, leaf quality and productivity of tea (var. TV-23). The pattern of nutrient uptake and soil physicochemicals properties were also itemized. The treatments were comprised of three doses of glufosinate ammonium 13.5% SL (0.27, 0.34, 0.45 kg/ha), glyphosate 41% SL (1.23 kg/ha), paraquat dichloride 24% SL (0.60 kg/ha) and weedy check within a randomized complete block design, replicated four times. The results revealed that glufosinate ammonium at 0.45 kg/ha was the most efficient against grassy and broad-leaf weeds with higher weed control efficiency (> 90%) and total green leaf yield (3.0 t/ha and 2.96 t/ha). Herbicides did not show any phytotoxicity symptoms on the matured tea plants throughout the observation period. An initial detrimental effect on rhizospheric micro-flora (total bacteria, fungi, and actinomycetes) was imposed by residual toxicity of herbicides but at later stage, no harmful effects were observed. Maximum nutrients uptake and soil available nutrients were determined under the higher dose of glufosinate ammonium. Tea leaf quality did not significantly influence by weed management practices. Based on overall performance, the glufosinate ammonium 0.45 kg/ha may be considered as the best substitute for others post-emergent herbicide against the complex weed floras in tea garden.

Enhancement of Green Leaf Yield in Tea [Camelia sinensis (L.) O Kuntze] as a Function of Pigments by Foliar Application of Triacontanol

Tricontanol is a natural plant growth regulator that possesses growth promoting activity and it is also able to increase leaf pigment and thereby improving yield of various crops. Plant pigments particularly leaf chlorophyll contents have widely been appraised as the most significant indicator of photosynthesis. Tea is one of the most important leverage in the world but its productivity needs to be increased to meet up the ever increasing demand of tea in coming years. Thus in the present experiment the effect of foliar application of triacontanol on green leaf yield as a function of chlorophyll and carotenoids contents of field grown mature tea was evaluated. Total six numbers of triacontanol (0.1% EW) treatments @ 0.3, 0.4, 0.5, 0.6, 0.8 and 1.0 ml l−1 of water, besides two control treatments, viz. untreated control and water spray were used. Total chlorophyll content in the various leaves viz. bud, 1st, 2nd and matured leaves were estimated during each plucking which was continued up to fourth round. It was observed that triacontanol exerted a markedly positive effect on leaf pigment contents and green leaf production of tea. The results further indicated that the total chlorophyll contents of matured leaves were positively associated with green leaf yield at fourth round of plucking. The application of triacontanol i.e. @ 0.5 ml l−1 at three weeks interval may be recommended for tea since this treatment was found to produce more green leaves as compared to others irrespective of plucking rounds.

Impact of foliar diseases and its interaction with nitrogen fertilization and fungicides mixtures on green leaf area dynamics and yield in oat genotypes with different resistance

Crown rust (Puccinia coronata f. sp. avenae P. Syd & Syd) and leaf spot [Pyrenophora avenae Ito and Kurib, anamorph Drechslera avenae (Eidam) Sharif] are considered the most important oat fungal diseases in the world, causing high yield and grain quality losses. A major aspect for the management of foliar diseases (mainly crown rust) is the use of host resistant; however most of the oat cultivars available behave as moderately resistant to susceptible. Considering this, fungicides application is a common method of control of fungal diseases in order to reduce yield losses. The objective of this work was to evaluate the effect of foliar diseases and the interaction between N fertilization and fungicides on green leaf area (GLAI), healthy area duration (HAD), grain yield and its components in three oat genotypes; two of them were genotypes obtained by the Breeding Program of the Facultad de Ciencias Agrarias y Forestales (FCAyF), Universidad Nacional de La Plata (UNLP) and a commercial cultivar (Bonaerense INTA Calén). The trials were carried out during two years using a split-split-plot design with three replications. Main plots were two environments: 2011–2014, the sub-plots were the fungicide treatments: with and without fungicide, the sub-sub plots were the fertilization treatments with 0 and 60 kg N.ha−1 and the sub-sub-sub plots were the oat genotypes. Fungicide application decreased the severity percentages at the three growth stages (GS) evaluated during 2014, whereas N fertilization caused increases in the severity of rust, which may be associated with the biotrophic habit of this causal pathogen. However, in the year with high levels of crown rust, N application did not cause effects in GLAI and HAD, due to the effect of N application in increasing the severity of the disease. Fungicide application increased GLAI, HAD and grain yield (GY) with higher responses in the most susceptible genotype (Calén). Results of this study suggest that relating HAD to Grain Yield could be an effective tool in order to improve the quantification and modelling of yield losses under foliar diseases infections. Moreover, the lines belonging to the breeding program of the FCAyF-UNLP showed values of resistance and grain yield superior to the commercial variety evaluated.

Effect of organic and inorganic fertilizers on growth, yield and nutrient use efficiency of clonal tea (Camellia sinensis)

Abstract. Mokaya BN, Chemining’wa GN, Ambuko JL, Nyankanga RO. 2018. Effect of organic and inorganic fertilizers on growth yield and nutrient use efficiency of clonal tea (Camellia sinensis). Cell Biol Dev 2: 15-26. This research observed how to boost tea yields in small-scale tea producers using inorganic NPK fertilizers yearly while the cost of fertilizers has been rising, resulting in a decrease in net returns. The influence of different rates of organic and inorganic fertilizers on the soil chemical characteristics, growth, yield, and nutrient usage efficiency of clonal tea was investigated in an experiment. In the 2014/2015 production year, experiments were put up in Kianjokoma, Embu County. Organic Rutuba® and inorganic NPK fertilizers were employed (26.5.5). No-fertilizer control, 625 kg NPK/ha, 937.5 kg NPK/ha, 1875 kg NPK/ha, 625 kg Rutuba/ha + 625 kg NPK/ha, 625 kg Rutuba/ha, 937.5 kg Rutuba/ha, and 1875 kg Rutuba/ha were the treatments. These treatments were repeated three times in a randomized full-block design. Green leaf yield, black made tea yield, leaf length, and leaf breadth were among the crop statistics obtained. The soil data collected at the trial included the pH, exchangeable acidity, organic carbon, micronutrients, and macronutrients. Plant utilization efficiency for nitrogen, phosphate, and potassium were also measured. The cost and net revenue of each fertilizer treatment were calculated as well. The data were subjected to analysis of variance, and the least significant difference test was used to separate the groups at p 0.05. Adding organic Rutuba to the soil raised the pH and the amounts of Mn, Cu, Fe, Zn, Ca, and Mg. Compared to the no-fertilizer control and farmers' practice, the application of 625 kg Rutuba/ha + 625 kg NPK/ha resulted in enhanced leaf length, breadth, fresh green leaf yield, and made tea yield. According to the findings, the application of Rutuba fertilizer considerably improved agronomic efficiency, apparent nutrient recovery, and partial factor productivity of N, P, and K compared to inorganic NPK fertilizer. The study also found that applying NPK 26.5.5 at rates more than 625 kg/ha did not affect growth, yield, nutrient usage efficiency, or net returns. However, because organic Rutuba has a low macronutrient level, the study indicated that it should not be used alone in tea manufacturing. More research is needed to discover the best NPK and Rutuba fertilizer mix, as well as the influence of organic Rutuba fertilizer on tea quality.

Spatiotemporal Attributes and Crop Loss Associated with Tan Spot Epidemics in Baby Lima Bean in New York.

Tan spot, caused by the pycnidial fungi Didymella americana and Boeremia exigua var. exigua, is a foliar disease affecting processing baby lima bean production in New York. Tan spot epidemics are prevalent, occur annually, and may result in substantial defoliation. The disease is controlled by the prophylactic application of fungicides to maximize green leaf area. Information on yield losses due to tan spot on baby lima bean yield and the benefits of fungicide applications is needed to justify investments in disease management. Four small-plot, replicated trials were conducted over 2 years in commercial baby lima bean fields to evaluate the efficacy of fungicides for tan spot control at Piffard and Leicester, NY. Applications of pyraclostrobin or boscalid significantly reduced tan spot incidence and severity compared with nontreated plots, and increased the number of leaves per stem. In 2016, the increase in green leaf area associated with fungicide application was also documented in canopy reflectance values at 830 nm. Despite the decrease in tan spot incidence and corresponding increase in crop health obtained from fungicides, this effect did not translate into significant increases in pod yield. This finding suggested that the relationship between green leaf area and yield is highly variable in baby lima bean. The spatial and spatiotemporal patterns of naturally occurring tan spot epidemics were also characterized in baby lima bean fields across western New York using disease incidence data collected in transects and grids. The spatial pattern of data collected in transects was analyzed using median runs analysis. Disease incidence data collected in two-dimensional grids were analyzed to quantify spatial pattern using spatial analysis by distance indices (SADIE). The association function of SADIE was used to quantify the spatiotemporal patterns of tan spot epidemics after crop emergence and at harvest. These findings suggested that tan spot is likely to initiate at relatively frequent, randomly positioned foci, and that subsequent, limited spread results in significant local aggregation. Hypotheses for inoculum sources and recommendations for tan spot control in baby lima bean fields in New York are discussed.

Evaluation of Different Clones (Grafts) of Kachnar (Bauhinia variegata L.) for Morphometric Characters in a Clonal Seed Orchard

Firstly thirty two genotypes of the species, collected from different areas, were evaluated for growth traits, mineral nutrients and proximate principles after four years in a previously raised progeny trial. In this way top eighteen genotypes were selected and grafted separately on seedling stock of the same species and a clonal seed orchard was established which consisted of eighteen clones (grafted) raised in RBD with three replications. After five years the observations were recorded on individual ramet viz; plant height, basal diameter, leaf width, leaf length, number of branches, petiole length and green leaf yield. Significant differences among clones were observed for different morphometric traits. Various genetic parameters and correlation coefficients for different growth characters were determined. The highest percent GCV (33.20) and PCV(36.02) as also heritability (84.95) were exhibited by green leaf yield while maximum GA (3.23) was noticed in leaf width. The highest percent GG (61.86) was recorded for green leaf yield. Significantly positive correlations were observed between plant height and basal diameter (0.6086), plant height and green leaf yield (0.8461), basal diameter and green leaf yield (0.6924), leaf width and leaf length (0.6490), leaf width and green leaf yield (0.5688) and leaf length and green leaf yield (0.4225).

Weather parameters vulnerability on tea production in north western Himalaya, India

The study assessed the sensitivity of weather parameters with respect to total green leaf and two leaves and bud (T & B) productivity of tea crop {Camellia sinensis (L.) Kuntze}. The maximum temperature ranging from 20.0 to 29.0 oC during March, May, August and September showed positive relationship with values ranging from 0.26 to 3.38 and 0.22 to 3.22 for green leaf and T & B yield, respectively. Similarly, minimum temperature ranging from 9.1 to 20.0 oC during March and July to October found positive 0.001 to 2.93 and 0.28 to 2.91 for green leaf and T & B productivity, respectively. The mean monthly rainfall amounting 52.7 to 664.7 mm during March, May, July to October and 52.7 to 488.4 mm during June, July, September and October also showed positive sensitivity with values ranging from 0.03 to 0.33 and 0.007 to 0.35 for green leaf and T & B yield, respectively. The relative humidity ranging between 41.2 to 77.3% during April to May for green leaf yield (0.32 to 1.71) and during April to May and October for two leaf and bud yield (0.00 to 1.70) showed positive relationship. So, maximum and minimum temperature between 20.0 to 29.0 oC and 9.1 to 20.0 oC, respectively with rainfall of 52.7 to 488.4 mm and relative humidity 41.2 to 77.3% are the most beneficial weather parameters for tea cultivation at Palampur conditions.

Effect of N and K levels on growth, yield and nutrient uptake of FCV tobacco cv. Kanchan

A field experiment was conducted during rabi, 2007-08 and 2008-09 at Jeelugumilli, Andhra Pradesh under irrigated Alfisols conditions to find out the effect of levels of nitrogen and potash on growth, yield and nutrient uptake pattern of flue-cured Virginia tobacco (Nicotiana tabacum L.) cv. Kanchan which is a heavy feeder and high yielder. The results of the experiment revealed that leaf dry weight increased from 30-90 days after planting with increase in N dose from 90 to 140 kg N/ha. Maximum accumulation of leaf dry weight was observed between 60-90 days after planting. Stem and root dry weight increased up to 120 days after planting during both the years. Green leaf yield and cured leaf yield increased progressively and significantly with increase in the N level from 90 to 140 kg N/ha. Higher grade index was recorded at 115 kg N/ha followed by 140 and 90 kg N/ha. The concentration of nitrogen in the leaf increased with increase in nitrogen dose but decreased with increase in level of potassium at the same nitrogen level. Nitrogen uptake increased with increased levels of N and K. Potassium content was high in the initial stages and slowly decreased with the advance in the age of the crop. Initially the difference in the uptake of N and K was narrow, the ratio widened with the age of the crop and finally the ratio was 1:1.3 to 1.4. Higher K uptake in leaf was observed at 115 kg N and while, higher K uptake in stem and root were observed at 140 kg N with 140 kg K2O /ha. The chemical quality parameters, viz. reducing sugars and nicotine in leaf lamina were within the acceptable limits. Higher green leaf yield, cured leaf yield, nitrogen and potassium uptake were recorded with application of 140 kg each of N and K2O/ha in FCV tobacco cv. Kanchan in irrigated Alfisols of Andhra Pradesh.

Performance of Different Clones of Morus alba for Morphometric Traits in a Clonal Evaluation Trial

Variation among different traits along with their correlation were studied in twenty seven clones of Morus alba . The significant differences were found among clones with respect to various morphometric traits. Moderate phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), heritability and genetic gain were recorded for green leaf yield, ramet height, leaf length, leaf width and basal diameter indicating that these characters can be more reliable for effective selection in future. Ramet height showed positive and significant correlation with basal diameter (0.5287), leaf length (0.4671), number of branches (0.6043), and green leaf yield (0.6893). Basal diameter, leaf length and leaf width also exhibited positive and significant correlation with green leaf yield i.e. 0.4705, 0.5714, 0.4813, respectively. Hence, these correlations can be useful in the indirect selection of the species.

Changes in Distribution and Frequency of Fungi Associated With a Foliar Disease Complex of Pyrethrum in Australia

In Australia, pyrethrum (Tanacetum cinerariifolium) is affected by a foliar disease complex that can substantially reduce green leaf area and yield. Historically, the most important foliar disease of pyrethrum in Australia has been ray blight, caused by Stagonosporopsis tanaceti, and other fungi generally of minor importance. Temporal fluctuations in the frequency of fungi associated with foliar disease were quantified in each of 83 fields in northern Tasmania, Australia, during 2012 and 2013. Sampling was conducted throughout winter (April to July), spring (August to September), and summer (November) representing different phenological stages. Microsphaeropsis tanaceti, the cause of tan spot, was the pathogen most prevalent and isolated at the highest frequency, irrespective of sampling period. The next most common species was S. tanaceti, whose isolation frequency was low in winter and increased in spring and summer. Known pathogens of pyrethrum, Alternaria tenuissima, Colletotrichum tanaceti, and Stemphylium botryosum were recovered sporadically and at low frequency. Two species of potential importance, Paraphoma chrysanthemicola and Itersonilia perplexans, were also found at low frequency. This finding suggests a substantial shift in the dominant pathogen associated with foliar disease, from S. tanaceti to M. tanaceti, and coincides with an increase in defoliation severity in winter, and control failures of the spring fungicide program. Factors associated with this finding were also investigated. Sensitivity of M. tanaceti and S. tanaceti populations to the fungicides boscalid and cyprodinil collected prior to and following disease control failures in the field were tested under in vitro conditions. A high proportion (60%) of the M. tanaceti isolates obtained from fields in which no response to the spring fungicide program was found were insensitive to 50 µg a.i./ml boscalid. This represented a 4.2-fold increase in the frequency of this phenotype within the M. tanaceti population over 2 years. No shifts in sensitivities to cyprodinil of M. tanaceti and S. tanaceti, or S. tanaceti to boscalid, were observed. Considering the increase in defoliation severity over winter, the benefits of applying fungicides in autumn, in addition to the commercial standard (spring only), were quantified in 14 individual field trials conducted in 2011 and 2012. Mixed-model analysis suggested fungicide application in autumn may improve pyrethrum growth during late winter and early spring, although effects on defoliation and yield were minimal. The increasing prevalence and isolation frequency of M. tanaceti and boscalid resistance within the population is of concern and highlights the urgent need for adoption of nonchemical methods for disease management in Australian pyrethrum fields.

Evaluation of Streptomyces spp. for effective management of Poria hypolateritia causing red root-rot disease in tea plants

A field study was conducted to evaluate the efficacy of indigenous biocontrol agents such as Streptomyces griseus and Streptomyces lydicus along with Bacillus subtilis and Trichoderma harzianum for controlling red root rot disease of tea plants. In response to biological treatments, disease incidence, green leaf yield, biometric and physiological parameters and organoleptic characters of made tea were assessed. Among the thirteen treatments tested, soil drenching of carbendazim was superior in terms of reducing red root rot incidence followed by combination of S. griseus and T. harzianum recorded in two consecutive field experiments. In contrast, the maximum green leaf yield and plant growth was achieved in soil application of these biocontrol agents. However, the performance of this dual combination of biocontrol agents was on par with systemic fungicide in terms of disease control. Correspondingly, the biometric, physiological and biochemical parameters were also considerably increased in biologically treated plants when compared to untreated control. The disease increased from 38.7% to 47.6% in untreated control plots and those plants were unhealthy in terms of leaf yellowing, stunted growth with heavy flowering, drying of branches and sudden death of bushes. The tea quality parameters such as theaflavin and thearubigin contents were significantly increased in the range of 0.75–1.43% and 10.38–13.22% respectively in biocontrol treated plants. This was also reflected in tea liquor characteristics. Our results suggested that the combination of biocontrol agents represent a promising alternative for effective management of red root rot disease in tea plants.

Cultivation Studies of Stevia rebaudiana Bertoni in Turkey

Stevia rebaudiana Bertoni which belongs to the Asteraceae family is a herbaceous perennial plant and native to Paraguay. Stevia leaves produce steviol glycosides (stevioside and rebaudiosides), zero calorie natural sweetener and may substitute sucrose as well as other synthetic sweeteners, being 200 – 300 times sweeter than sucrose. Adaptation studies in Mediterranean climate condition of Antalya in Turkey was started four years ago and, initially seed germination problem was solved using cross-pollination of stevia flowers. The aim of this study was to determine some plant traits such as plant height, plant weight, number of stem per plant, leaf yield, leaf/stem ratio, days for flowering, stevioside and rebaudioside A rates of stevia in the conditions of Antalya. The experiment was carried out in randomized plots design with four replications for two years. Row spacing and intra-row spacing applied were 65 cm and 45 cm, respectively. In the experimental plots, drip irrigation was used and weeding was controlled by using garden tools. No fertilizers were applied to the plots. Plants were harvested at the beginning of the flowering time using pruning shears. According to the results, average plant height was found 98 cm, average number of stem per plant was found 9, average plant weight value was recorded as 720 g, average leaf/stem ratio was 1.03, average green leaf yield per hectare was found 8.6 tonnes, average days for flowering was 160 days, stevioside and rebaudioside A rates was found as 8.2% and 3.5%, respectively. In conclusion, stevia could be cultivated successfully in the conditions of Antalya as a perennial crop.

Efficacy of various fungicides and indigenous biocontrol agents against red root rot disease of tea plants

An experiment was conducted to study the effectiveness of contact, systemic and botanical fungicides, and indigenous biocontrol agents in controlling red root rot disease of tea plants. In general, all tested bioagents, the combination of Pseudomonas fluorescens and Trichoderma atroviride reduced red root disease incidence recorded in two consecutive field experiments. Among the fourteen treatments tested, soil drenching of systemic fungicides was superior but similar to the combination between P. fluorescens and T. atroviride. In contrast, the maximum green leaf yield and plant growth was achieved when soil application of biocontrol agents was carried out. However, the performance of these biocontrol agents under various combinations was on par with systemic fungicides, but superior to botanical fungicides. Correspondingly, the physiological and biochemical parameters were also greatly increased in plants in several treatments when compared to untreated control. The disease increased from 31.5 % to 40.0 % in untreated control plots and those plants were unhealthy in terms of leaf yellowing, stunted growth with heavy flowering, drying of branches and sudden death of bushes. The tea quality parameters were significantly improved in treated plants including total liquor colour, thearubigins, theaflavins, highly polymerized substance and caffeine contents.

Performance Of Coriander Cultivars For Green Leaf Production Under Late Sowing Condition

A field experiment was conducted at the research farm of Institute of Agriculture and Animal Science, , Chitwan, Nepal from December 2009 to March 2010 to study the green leaf production potential of coriander (Coriandrum sativum L.) cultivars. Ten cultivars of coriander were evaluated in a Randomized Complete Block Design (RCBD) replicated three times. Coriander Local, Marpha Local, Mallika, Surabhi and Kalmi Chhattedar showed better performance as compared to others on growth, yield and quality parameters. The highest green leaf yield (10.09 mt/ha) was recorded in Coriander Local followed by Mallika (9.54 mt/ha), Surabhi (9.40 mt/ha) and Kalmi Chhattedar (9.24 mt/ha). Surabhi was found promising cultivar under late sowing condition because if its highest rosette diameter, number of basal leaves and length of basal leaf Hence, there is good scope of coriander cultivation for green leaf production, however, it is more suitable to sow the seeds in usual tome of sowing for the better performance of all the cultivars. The Journal of Agriculture and Environment Vol:12, Jun.2011, Page 67-73 DOI: http://dx.doi.org/10.3126/aej.v12i0.7565

Sensors and imaging techniques for the assessment of the delay of wheat senescence induced by fungicides.

Near-range and remote sensing techniques are excellent alternatives to destructive methods for measuring beneficial effects of fungicides on plant physiology. Different noninvasive sensors and imaging techniques have been used and compared to measure the effects of three fungicidal compounds (bixafen, fluoxastrobin and prothioconazole) on wheat (Triticum aestivum L.) physiology under disease-free conditions in the greenhouse. Depending on the fungicidal treatment, changes in green leaf area and yield parameters were observed. Chlorophyll fluorescence of leaves was useful for measuring differences in the effective quantum yield of PSII. Reflectance measurements of wheat leaves were highly sensitive to changes in plant vitality. The spectral vegetation indices were useful for determining the differences among treatments in terms of leaf senescence, pigments and water content. The analysis of ear and leaf surface temperature was reliable for detecting effects of fungicides on plant senescence. Using nondestructive sensors, it was possible to assess a delay in senescence of wheat due to fungicide application. Furthermore, it was deduced that sensors and imaging methods are useful tools to estimate the effects of fungicides on wheat physiology. Physiological parameters measured by the sensors were actually more sensitive than yield parameters to assess the effect caused by fungicide application on wheat physiology.

Management of Cephaleuros parasiticaus Karst (Trentepohliales: Trentepohliaceae), an algal pathogen of tea plant, Camellia sinsensis (L) (O. Kuntze)

The efficacy of certain biocontrol agents were evaluated against Cephaleuros parasiticus Karst, a causal organism of red rust disease in tea plants. Spraying of systemic fungicides was found to be superior to biocontrol agents followed by algicides in controlling the disease under field condition. Dipping of shears in the solutions of fungicide, detergent or biocontrol agents failed to protect the disease spread. The study on the impact of different harvesting practices on disease development showed the highest disease incidence in continuously shear harvested fields and least in hand plucked fields. There was a reduction in disease incidence in spraying of a solution containing urea and murate of potash mixture at 1% level. The maximum green leaf yield and productivity index were recorded in biocontrol agents treated plots. Among the various group of biocontrol agents evaluated, Streptomyces sannanensis and Streptomyces griseus belong to actinomycetes was better than bacterial and fungal antagonists in terms of disease protection and increase in yield potential. Similarly, tea bush canopy architecture, physiological and biochemical parameters were also increased in plants treated with biocontrol agents. In the case of untreated control plots, the disease incidence was increased from 36% to 44.5% and the plants were found unhealthy in terms of chlorosis, stunted growth and heavy flowering with banji buds. The shoots collected from treated and untreated control plots were subjected to manufacture CTC black tea which revealed almost all the tea quality parameters were significantly improved in the treated plot over the untreated plots.

Influence of potassium solubilizing bacteria on crop productivity and quality of tea (Camellia sinensis)

A field experiment was conducted to study the efficacy of indigenous potassium solubilizing bacteria (KSB) in combination with various dosages of potash fertilizers along with recommended dose of nitrogen (N) and phosphorus (P) fertilizers in tea plants. Soil and leaf samples were drawn from the respective plots and they were subjected for the analysis of various parameters related to nutrients and quality aspects. Among various treatments, plants treated with N100 P100 K75 + KSB concentration formulation was found to be the best in terms of high chlorophyll, carotenoid, N, P and K contents in the crop shoots followed by other treatments. Significantly higher yield of the green leaf was achieved by the same treatment. K content in soil and also in crop shoots was greatly improved due to the application of KSB along with possible reduced doses of potash source. On the other hand, N100 P100 K25 + KSB formulation and untreated control plots have exhibited least green leaf yield and nutrient status of soil and crop shoots. The biochemical parameters, total polyphenols, catechins, amino acids and sugars were significantly at higher level in plants after imposing treatments in combination with KSB. Biometric parameters such as plucking surface of the tea bush canopy, plucking points per unit area, internodal length, leaf moisture and dry matter contents were analyzed and found to be high in tea plants treated with N100 P100 K75 + KSB combination. Banji content was significantly reduced invariably in all the treatments except the untreated control plots. Evaluation of KSB population in soil revealed thatwherever KSB was incorporated, there was a significant increase in population level and has coincided with dehydrogenase enzyme activity. The flush shoots of tea comprising of three leaves and a bud were subjected to manufacture black tea, and it was revealed that almost all the tea quality parameters such as theaflavin, thearubigin, highly polymerized substances, total liquor colour, caffeine, briskness, colour and flavour indexes were greatly improved in KSB treated plants, which in turn improve the quality as well. This finding confirms that the influence of indigenous potassium solubilizing bacteria upon potassium nutrient exhibited improvement in the productivity and nutrient uptake in plants and retained in soil including quality parameters in tea plantations. Key words: Tea, potassium solubilizing bacteria, biofertilizer, nutrient status, crop productivity, tea quality.

Evaluation of various fungicides and microbial based biocontrol agents against bird’s eye spot disease of tea plants

A field experiment was conducted to study the efficacy of six fungicides comprising contact, systemic and botanical fungicides and three biocontrol agents for the management of bird’s eye spot disease in tea plantations. Among 16 treatments, systemic fungicides were found to be superior to biocontrol agents in controlling the disease whereas the maximum green leaf yield was significantly increased in those applied with biocontrol agents. On the whole, Streptomyces sannanensis offered the maximum yield of 3998 kg ha −1 made tea followed by Trichoderma harzianum (3884 kg ha −1 made tea). Between the two different carrier materials evaluated for the application of biocontrol agents, vermicompost-based bioformulation showed better efficacy than talc-based formulation. Of the three (bacteria, fungi and actinomycetes) groups of biocontrol agents, S. sannanensis was better than Pseudomonas fluorescens and Trichoderma atroviride belonging to bacterial and fungal antagonists; respectively in terms of disease protection and increasing yield potential. Similarly, the biometric, physiological and biochemical parameters were also increased in plants greatly after imposing various treatments. Plucking surface of the bush, number of plucking points per unit area, internodal length, leaf moisture and dry matter contents were found higher in plots applied with biocontrol agents than those treated with fungicides. Almost all of the tea quality parameters such as total liquor colour, thearubigins, theaflavins, highly polymerized substance and caffeine were significantly improved in biocontrol treated plants. Theaflavin and thearubigin contents were increased in the range of 9.00–9.57% and 1.27–1.54% respectively in vermin based treatment. Similarly the amount of caffeine content (3.66–4.08%) and flavour index (4.18–5.31%) were considerably enhanced.

Energy and Protein Supplementation Can Improve Liveweight Gain of Steers Grazing Good Quality Tropical Pasture in the Wet Season

This experiment aimed at maximising wet season liveweight gain (LWG) of cattle grazing good quality tropical pasture. Twenty-five Brahman crossbred steers (203 ± 4.2 kg) were allocated into 5 treatments, namely control (Con; grazing only), grazing + molasses/urea mixture (MU) at 0.5% liveweight (LW) (5MU) or 1% W (10MU), and grazing + mixture of molasses/urea (55%), fish meal (25%) and whole cottonseed (WCS; 20%) at 0.5% W (5MWF) or 1% W (10MWF). Steers grazed fertilized pangola grass pasture (Digitaria eriantha cv. Steudal) for 84 days. Pasture DM availability was maintained at > 1.5 t/ha. The Mean green leaf yield was 1.9 t DM/ha, in vitro DM digestibility was 64%, and crude protein content was 15%. The LWG of Con steers was 960 g/d. Providing MU did not increase LWG, but inclusion of fishmeal and whole cottonseed markedly improved LWG above control by 34% and 39% for 5MWF and 10MWF, respectively. Levels of supplement had no affected on LWG. It is concluded that supplementing rumen fermentable energy and protein alone did not increase LWG of steers grazing good quality tropical grass pasture, but the inclusion of rumen bypass protein and energy in supplement significantly increased LWG, as a result of the higher bypass protein and energy intake.

Estimation of Technical Efficiency and It's Determinants in the Tea Small Holding Sector in the Mid Country Wet Zone of Sri Lanka

Sri Lanka is the world leader in made tea production and the small holding sector dominates national production by accounting for 60% of the island's tea production. However, given the high cost of production, there is a belief that it is very difficult to increase profitability without increasing costly inputs such as labour. With this background, in this study technical efficiency of the tea small holdings sector in the Mid Country Wet Zone of Sri Lanka was estimated in order to identify the potential to increase production without incurring any additional costs for inputs. The sources of inefficiency and the robustness of measured technical efficiency in various functional specifications was also investigated. The primary data collected during the period September - January 2001 relevant to sixty small holder tea producers in the Mid-country Wet Zone was used for the study. Maximum likelihood estimates of the stochastic frontier model were estimated for green leaf yield as a function of land extent, family labour, hired labour, fertilizer, chemicals, and dolomite, using Cobb- Douglas and translog models. The determinants of technical efficiency such as age of farmer, experience, education, occupation type of crop (VP/Seedling) and type of clone were investigated, following the Battese and Coelli (1995) specification. According to the Cobb-Douglas specification, extent of land, family labour, hired labour, fertilizer and dolomite showed significant effects on yield. The coefficients for land, family labour, hired labour and fertilizer had positive values of 1.11, 0.027, 0.067 0.029 and 0.004 respectively. The mean technical efficiency of the tea small holdings sector in the Mid Country Wet Zone was found to be 64.60 per cent. The result for the inefficiency model indicates that age of farmer, education, occupation, type of crop (VP or seedling) and type of clone have significant effects on efficiency. The coefficients for age, education, occupation and type of crop showed negative values. However contrary to expectations, type of clone and experience showed positive values. The estimation with the translog model yielded different technical efficiencies, which indicates the fact that technical efficiency estimations are highly sensitive to the functional form specified. DOI: http://dx.doi.org/10.4038/sjae.v4i0.3488 SJAE 2002; 4(1): 137-150