https://www.myresearchjournals.com/index.php/IJTS/issue/feed 2021-09-03T11:27:11+02:00 Open Journal Systems <p>The GENESIS of this Journal may be traced back to October 1996 when the International Conference on Global Advances in Tea Science, held in Delhi identified the gaping chasm in the generation and dissemination of tea information to concerned users. The delegates recommended a refereed research journal, exclusive to tea, published by a registered society. The International Society of Tea Science (ISTS) was launched with the help of the National Institute of Science, Technology &amp; Development Studies (NISTADS).&nbsp;</p> https://www.myresearchjournals.com/index.php/IJTS/article/view/3840 2021-09-03T11:27:10+02:00 Joel K. Langat [email protected] Rose C. Ramkat [email protected] Richard Mose [email protected]

Many fungi play a vital role in the decomposition of wood in nature and nutrient cycling, yet some afflict serious damage to cultivated tree crops and forestry. Tea (Camellia sinensis (L) O. Kuntze) is affected by Hypoxylon wood rot (HWR) disease caused by the Hypoxylon sp. Pers ex Fr. In the recent years; there have been reports on increase of the disease in Kenya. This study aimed at determining disease incidence and biodegradation by 59 Hypoxylon isolates from diverse tea growing counties of Kenya on wood, from resistant (TRFK 6/25) and susceptible (TRFK 6/129) tea cultivars. The disease incidence varied (p less than or eqaul to 0.05) in different counties (6.7 to 77.5%) and was more prevalent in tea cultivars (77.5%) than seedling type of teas (15.7%). Bio-degradation of wood was performed in Falcon tubes for 40 days. The 59 Hypoxylon isolates significantly (p less than or eqaul to 0.05) bio-degraded tea wood. The weight loss ranged from 4.84 to 16.44% in the susceptible and 4.61 to 12.64% in the resistant cultivars. The results indicate the potential use of biodegradation to evaluate resistance of tea cultivars to damage by Hypoxylon sp. This study concludes that biodegradation is potentially usable technique to screen tea cultivars for resistance to HWR.

2020-09-30T00:00:00+02:00 ##submission.copyrightStatement## https://www.myresearchjournals.com/index.php/IJTS/article/view/3841 2021-09-03T11:27:11+02:00 R. C. Muoki [email protected] P. N. Kamau [email protected] S. M. Kamunya [email protected] O. Kiplagat [email protected] C. Kawira [email protected]

A key step in characterization of germplasm is the identification of phenotypic variation present in a given population. A study was carried out to determine the effect of different dosages of gamma rays (50 and 100Gy) on phenotypic variation using 21 standardized morphological descriptors of the UPOV Tea Test Guidelines. The trial comprised of open-pollinated seed stocks from six commercial tea cultivars namely TRFCA SFS150, TRFK 303/1199, EPK C12, GW Ejulu-L, TRFK 301/1 and TRFK 301/4 along with untreated controls. Data was collected for three seasons (dry, warm wet and cold wet) using five randomly selected plants from each treatment. Principle Component Analysis using 17 informative descriptors showed the first eight principal components accounted for 78% of the total variance, with 15 being highly informative. Cluster analysis further identified characters such as young shoot anthocyanin colouration at base of the petiole, leaf blade shape/color/length, shoot color/length, density of pubescence, plant vigour and density of branches as most discriminating descriptors resulting in four phenotypically well-defined groups. Most traits showed significant correlation, an indication that the traits could be used for indirect selection. The study provides a basis for rapid and early screening of base populations for identification of elite cultivars.

2020-09-30T00:00:00+02:00 ##submission.copyrightStatement## https://www.myresearchjournals.com/index.php/IJTS/article/view/3842 2021-09-03T11:27:11+02:00 Robert O. Ombori [email protected] P. Okinda Owuor [email protected] David M. Kamau [email protected] Bowa O. Kwach [email protected] Wilson Dufitumukiza [email protected] Solomon W. Msomba [email protected]

Eastern Africa tea grows in high rainfall areas where nutrients depletion through leaching, and surface run-off can be high, in addition to removal with crop. Nutrients replenishment through fertilizer applications is therefore necessary. But inappropriate fertilizer use can cause nutrients imbalance, change soil pH, and organic carbon contents. Variations in plucking intervals result in differences in tea productivity. Although environmental factors vary within Eastern Africa tea growing regions, recommended fertilizer type and rates and harvesting intervals are largely uniform. Fertilizer use and harvesting policy may influence soil chemical parameters within the region to varying degrees. Effects of NPKS 25:5:5:5 fertilizer rates and plucking intervals on soil organic carbon, pH and the relationship between soil organic carbon, pH and tea yields in Eastern Africa were evaluated. Trials were conducted on clone TRFK 6/8 at Timbilil, Changoi, Arroket (Kenya), Maruku, Katoke (Tanzania), Kitabi and Mulindi (Rwanda). Soil organic carbon contents ranged from 4.16 to 17.61% and were sufficient. Increasing nitrogen rates increased (p less than or eqaul to 0.05) soil organic carbon but lowered (p less than or eqaul to 0.05) soil pH. The pH values ranged between 3.22 and 4.84. The increase in soil acidity due to high rates of nitrogen rates reduce tea productivity in the long run. Periodic monitoring of soil pH is necessary in tea production to invoke mitigation activities when decline below 3.5. Plucking intervals had no influence on SOC and pH at all sites. Soil organic carbon and pH varied significantly (p less than or eqaul to 0.05) from location to location, though the values were within acceptable range. Soil organic carbon directly correlated (r.>0.878; p less than or eqaul to 0.05 for all sites except Mulindi and Maruku) with yields and inversely (r less than or eqaul to -0.878, p less than or eqaul to 0.05 for most sites) with pH. The correlation between SOC and yields suggest that tea production management need to maintain SOC at optimal levels realization of sustained tea yields.

2020-09-30T00:00:00+02:00 ##submission.copyrightStatement## https://www.myresearchjournals.com/index.php/IJTS/article/view/3843 2021-09-03T11:27:11+02:00 Rosebell A. Owuor [email protected] Alphonce J. Odondo [email protected] P. Okinda Owuor [email protected] David M. Kamau [email protected]

Tea sector contributes approximately 30% of export earnings in Kenya. Despite the industry continuing to realize positive gross margins, high costs of production coupled with weak trends in export prices threaten its future contributions. Nitrogen fertiliser is mandatory in tea production and its appropriate use promotes tea growth rate and yields. Previous studies using different tea cultivars established that optimal fertiliser rates varied with clones and geographical area of production. However, economics of nitrogenous fertilisers use on same tea cultivar in different tea growing regions in Kenya remains undefined. This study evaluated response of NPKS 25:5:5:5 fertiliser applied at 0, 75, 150, 225 and 300 kg N/ha/year on clone BBK35 to determine the viable economic rate under uniform management in different locations (Karirana, Timbilil, Changoi, Sotik Highlands and Kipkebe) within Kenya. The study used time series tea yield data and corresponding variable costs from field experiments running from 1997 to 2007. The data were subjected to Partial Budget Analysis (PBA) procedures for economic analysis of on-farm experiments. The economic returns varied with rate of nitrogen and region of production. Maximum marginal rate of return (MRR) were achieved at 75 kg N/ha/year at Kipkebe, Changoi and Timbilil, and 150 at Sotik Highlands and Karirana. However best economic returns were recorded at 300 kg N/ha/year in Kipkebe and Sotik Highlands, 225 kg N/ha/year in Changoi, and at 150 kg N/ha/year in Timbilil and Karirana. These results demonstrate that current uniform fertiliser recommendation rate of 100 to 220 kg N/ha/year may not be suitable for all regions. There is need to develop region specific nitrogen fertiliser requirements for tea growing areas in Kenya.

2020-09-30T00:00:00+02:00 ##submission.copyrightStatement## https://www.myresearchjournals.com/index.php/IJTS/article/view/3844 2021-09-03T11:27:11+02:00 R. C. Muoki [email protected] J. A. Maangi [email protected] R. K. Korir [email protected] J. L. Bargul [email protected] S. M. Kamunya [email protected]

Molecular markers are useful tools for studying gene flow and genetic diversity within a population. With the establishment of online databases, sequence can be now be downloaded for identification of Expressed Sequence Tags- Simple Sequence Repeat (SSR) markers designed to amplify the microsatellite loci present in the genes. Of the 170 microsatellites detected from the downloaded 789 ESTs belonging to the nine Camellia spp, only fourteen showed functional EST-SSR markers. Among them, five polymorphic markers specific to tri-nucleotide SSRs were randomly selected and screened alongside five established primers on four tea genotypes (TRFK 570/2, TRFK 688/1, TRFK 83/1, and TRFK 6/8,) The polymorphism information content (PIC) of the SSR markers had mean of 0.33 that ranged between 0.16 and 0.53, whereas discriminating power (D) had mean value of 0.23 ranging between 0.00 and 0.75 with. A total of 64 alleles were detected with an average of 6.4 alleles per SSR locus. Based on a PIC greater than or equal to 0.40, D value greater than or equal to 0.20 and number of polymorphic bands greater than or equal to 1, five functional SSR markers comprising two novel EST-SSRs (Camjap A1, Camjap A4) and three adapted microsatellite markers (TM 134, A37, and A47) were recommended for use in discriminating interspecific hybrids of tea.

2020-09-30T00:00:00+02:00 ##submission.copyrightStatement## https://www.myresearchjournals.com/index.php/IJTS/article/view/3845 2021-09-03T11:27:11+02:00 Wilson Dufitumukiza [email protected] P. Okinda Owuor [email protected] Joseph Bigirimana [email protected] Ange R. Akingeneye [email protected] Balthazar Murenzi [email protected]

Tea in Rwanda, is grown in different agro-ecosystems comprising highlands and drained low elevation peatlands. The plantations use uniform agricultural practices imported from Eastern Africa countries, but without re-testing for suitability. The practices include nitrogenous fertilizer use and harvesting, which are most expensive agronomic inputs in tea cultivation. These practices need optimization for tea the growers to realise maximum tea production. Trials were conducted for eight years using clone TRFK 6/8 fields in Kitabi and Mulindi to evaluate influence of nitrogen fertiliser rates and plucking intervals on tea yields. Nitrogen (NPKS 25:5:5:3) rates used were 0, 75, 150, 225 and 300kg N/ha/year and plucking intervals were 7, 14 and 21 days. Tea yields were higher (p less than or equal to 0.05) in Kitabi than in Mulindi, implying tea productivity in Rwanda vary with geographical region of production. Although mean site yields demonstrated increase (p less than or equal to 0.05) with nitrogenous fertiliser rates, responses varied between the two sites. At Kitabi, annual yields increased (p less than or equal to 0.05) with nitrogen rates, peaking at 225 N ha/year. At Mulindi, significant (p less than or equal to 0.05) response to nitrogen rates was observed in only one year. Application of fertiliser was therefore necessary in Kitabi, while in Mulindi, little benefit was realised from nitrogen fertiliser use. Yields increased (p less than or equal to 0.05) with short plucking intervals at both sites throughout the eight years. Shortening plucking intervals can therefore improve tea production in Rwanda.

2020-09-30T00:00:00+02:00 ##submission.copyrightStatement##