Browsing by Author "Isutsa, Dorcas K."

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Effects of integrated nutrient sources on growth and yield of strawberry grown under tropical high altitude conditions.
(Horticultural Association of Kenya, 2008) Odongo, T.; Isutsa, Dorcas K.; Aguyoh, J. N.; ; ;
Strawberries are popular both in fresh and processed forms because of their enormous values. Low soil fertility is among major factors constraining strawberry productivity in Kenya. Consequently, effects of cattle farmyard manure (FYM) (0, 18, 36, and 54t/ha) in combination with triple super phosphate (TSP), equivalent to 0, 17, 34 and 68kg/ha phosphorus on strawberry productivity, were tested in split plots embedded in randomized complete block design, replicated three times. Farmyard manure formed main plots, whereas TSP formed sub-plots. Each treatment had 10 plants spaced at 0.3m´0.45m in double rows per plot, measuring 0.6m´1.5m. The plots were mulched with black polyfilm, irrigated with 2.5.cm diameter drip lines, and separated with a 0.5m trench. The study was done in three seasons (August 2003-July 2004, Feb. 2004-Jan. 2005, and July 2005-June 2006). Each season was conducted in new plots. Growth and fruit yield were assessed from 3 to 6 and 6 to 12 month after planting, respectively. Since seasons 1 and 2 data were not significantly different they were pooled and reported as season 1, whereas the different season 3 data were reported separately as season 2. Generally, the 54t/ha FYM promoted the highest growth, although not significantly different. Phosphorus (P) significantly (P<0.05) increased root biomass, and root: shoot biomass ratio. The effects of FYM, P and interaction on fruit yield were not consistent. The 36 and 54t/ha FYM resulted in the highest fruit weight in seasons 1 and 2, respectively. Phosphorus did not significantly (P>0.05) influence fruit weight, although 17 and 34kg/ha P yielded highest in seasons 1 and 2, respectively. The effect of interaction on cumulative yield was not significant in both seasons. Thus the observed variation was also attributed to soil and seasonal effects. Based on the current results, 36 t/ha to 54t/ha FYM and 17 kg/ha to 34kg/ha P are recommended for enhancing strawberry productivity under conditions similar to the ones for the present study. Phosphorus should only be applied where soil tests show deficiency.
Growth of ranunculus cutflower under tropical high altitude conditions.
(Horticultural Association of Kenya, 2009) Mayoli, Rose N.; Isutsa, Dorcas K.; Tunya, G.O; ; ;
Cutflower production and marketing is partly challenged by lack of new, exciting and improved varieties to satisfy customer needs of a different flower. Ranunculus (Ranunculus asiaticus L.) is a bulbous plant that originated in the Mediterranean basin region where growth and development take place optimally in cool, moist winter season. The extent of dormancy breaking and growth of this flower in tropical conditions is not known. Consequently, the present research studied the effects of shade and gibberellic acid (GA3) in breaking dormancy and reducing high light intensity and high temperature so as to assure optimal growth of R. asiaticus under tropical conditions. The fixed factors were: four GA3 levels (0, 100, 500 and 1500 mg/L) and three shade intensities (0%, 40% and 80% shade). The experiment was laid out in split plots arranged in randomised complete block design, replicated three times and repeated in two seasons. Tuberous roots were soaked in the respective GA3 concentrations for 10 minutes followed by planting under shaded plots. Data were recorded from sprouting through tuberous root formation stages. Season 1 (June to November 2006) was characterised by cool temperatures, whereas season 2 (December 2006 to April 2007) was characterised by warm temperatures. The 80% shade promoted significantly longer stems. Nevertheless, early flowering, highest quality flower stem diameter, flower bud initiation, flower head diameter and tuberous root fresh weight resulted for 40% shade. These quality parameters were highest in tuberous roots that had been soaked in 100 mg/L GA3 pre-plant. Therefore, growers in tropical high altitudes should use 80%, 40% and 0% shade in hot, warm and cool seasons, respectively. Pre-soaking of the tuberous roots in 100 to 500 mg/L GA3 is optional, depending on the desired growth magnitude and speed desired.
Growth of ranunculus cutflower under tropical high altitude conditions. 2: Effects of GA3 and shade on light intensity and temperature modification
(Horticultural Association of Kenya, 2009) Mayoli, Rose N.; Isutsa, Dorcas K.; Tunya, G.O; ; ;
Customer needs of a different flower are increasing over time worldwide. Many bulbous plants including ranunculus fit the category of a different flower because they are not known. Ranunculus(Ranunculus asiaticusL.),commonly known as Persian Buttercup or Asiatic Crowfoot,is a bulbous plant native of the cool Mediterranean basinregion. The growth of GA3and shade-treated ranunculus cutflower in relation to lightintensity (LI) and temperature under tropical high altitude conditions is not documented. An experiment was conducted to determine these relationships.The fixed factors were four GA3levels (0, 100, 500, 1500 mg/L) and three shade levels (0%, 40% and 80%shade). The experiment was set up in split plots arranged in randomised complete block design, replicated three times and repeated once. Tuberous roots were soaked in the respective GA3solutions for 10 minutes followed by planting under the shaded plots.Data were recorded from sprouting through tuberous root formation stages.The relationship of sprouting was negative quadratic with LI, positive linear with soil temperature (ST) in season 1 (cool), and negative linear with ST in season 2 (warm). The relationship of time to flower formation with LI was negative linear in season 1 and positive linear in season 2. The relationships of flower stem length with LI and air temperature (AT) were negative linear. The relationships of flower buds per stem, flower stem diameter, flower head diameter and tuberous root fresh weight with either LI or AT were negative quadratic. Therefore, shade modifies both LI and temperature that then interact in influencing growth of GA3-treated ranunculus. About 40000 lux LI and moderate seasonal temperature, both prevailing under 40% shade are ideal for best growth of ranunculus. Shade should be applied as follows: 0%, 40% and 80% in cool, warm and hot seasons, respectively.
Influence of Biozyme® on chlorophyll content, flowering and physiological maturity of potato (Solanum tuberosum L.) cultivars
(2013-09-19) Karanja, Benard K.; Isutsa, Dorcas K.; Aguyoh, Joseph N.; ; ;
The study was conducted at Egerton University in 2010/2011 in a split plot experiment, arranged in a randomized complete block design. The research was replicated three times and repeated once. Main plots were assigned to potato cultivars (Tigoni and Asante), while subplots were assigned to Biozyme® foliar feed rates (0, 125, 250, 500 and 750 ml/ha). Each subplot was planted with 28 seed potato tubers spaced at 30 cm x 70 cm in four rows. A distance of 1 m separated adjacent subplots and main plots. During the growth period, data collected included chlorophyll content, flowering characteristics and days to potato physiological maturity which was subjected to analysis of variance and means separated using LSD at P=0.05. Biozyme® application increased the chlorophyll content and flowering characteristics but reduced the days to physiological maturity. The 750ml/ha Biozyme® foliar feed increased chlorophyll content by 19.45spads, number of flowers set by 21.86%and reduced the days to physiological maturity by 21 days as compared to the control rate (0 ml/ha). Increased chlorophyll content and better flowering exhibited by effects of Biozyme® are good characteristics as these parameters impact on poato growth and development that determine potato yield.
Optimization of seed potato (Solanum tuberosum L.) tuber yield and size distribution through integrated irrigation water, nitrogen and phosphorus mineral nutrient application.
(Science Domain International, 2013-12-16) Gathungu, Geofrey K.; Aguyoh, Joseph N.; Isutsa, Dorcas K.; ; ;
Potato is the world's fourth important food crop after wheat, rice and maize because of its great yield potential and high nutritive value . In Kenya, potato is constrained by low seed tuber production in the informal sector. This is partly due to improper fertilizer regimes and irregular rainfall patterns. Therefore, a study was conducted in a rain shelter at the Horticultural Research Farm of Egerton University in Kenya from 19th August to 19th December 2011 (Trial I) and 5th April to 6th August 2012 (Trial II) to determine the effects of integrated irrigation water, nitrogen (N) and phosphorus (P) supply on tuber yield and size distribution. The layout was a split split plot design with irrigation (40%, 65% and 100% field capacity) assigned to main plots, N (0, 75, 112.5 and 150 kg N/ha) to subplots and P (0, 115, 172.5 and 230 kg/ha P2O5, corresponding to 0, 50.6, 75.9, 101.2 kg P/ha) to sub-subplots. The treatments were replicated three times and repeated once. The irrigation water rates were applied in drip tube lines.Nitrogen was supplied as urea (46% N) in two equivalent splits, at planting time and at 5 weeks after planting. Phosphorus was supplied at planting time as triple superphosphate (46% P2O5). Data were collected on number, yield and size distribution of tubers at harvest and subjected to analysis of variance. Significantly different means were separated using Tukey’s Studentized Range Test at P= 0.05. The 65% irrigation water and the high N and P rates resulted in relatively high number, yield and quantity of seed potato sizes I and II. The 100% irrigation water increased the ware -sized seed potato tubers and reduced the quantity of chats. Therefore, integration of moderate irrigation water and high rates of N and P is recommended for optimizing seed potato tuber grades.