Browsing by Author "Aguyoh, J. N."

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Climate change adaptation of potato (Solanum tuberosum L.) 2: Influence of Biozyme® rate on potato growth and development.
(2013-07-31) Karanja, B. K.; Isutsa, D. K.; Aguyoh, J. N.; ; ;
Potato is an important food crop worldwide. Growers adopt potato production due its short growing season and poor soils tolerance. They use agrochemicals to improve growth under unreliable rainfall. Biozyme® foliar feed is widely used to hasten maturity and enhance yields of crops. It is said to be a storehouse of hormones and nutrients that improve crop health. It contains major hormones along with primary and secondary nutrients. This study determined if Biozyme® could overcome deficit rainfall and enhance potato growth to adapt to climate change. The arrangement was split plots in randomized complete block design replicated three times and repeated once. Main plots were assigned to potato cultivar (Tigoni and Asante) and subplots to Biozyme® rate (0, 125, 250, 500 and 750 ml/ha). Each subplot was planted with 28 tubers spaced at 30 cm x 70 cm in four rows. A distance of 1 m separated plots. Plant growth in height, stem diameter and aboveground biomass increased with increase in Biozyme® rate. The 750 ml/ha rate increased height by 41%, stem diameter by 55.34%, chlorophyll by 19.45 spads, flowers by 21.86%, as compared to the control rate (0 ml/ha), but was not significantly different from 500 ml/ha rate. Increased height, leaf area index, chlorophyll content, aboveground biomass is good as it enhances photosynthate synthesis and translocation to edible tubers. Thus, foliar-feeding potato plants with at most 500 ml/ha Biozyme® is recommended for hastening growth in regions with deficit rainfall.
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.
Irrigation rate and mulch type significantly affect growth and flowering of purple passion fruit (Passiflora edulis f. edulis Sims).
(2011) Gaturuku, G. K.; Isutsa, D. K.; Aguyoh, J. N.; ; ;
Purple passion fruit (Passiflora edulis f. edulis Sims.) is an important fruit in the tropics, but its growth can be adversely affected by drought stress. This study evaluated effects of irrigation rate and mulch type on drought stress amelioration in purple passion fruits. The experiment was set up in a rain shelter in a randomized complete block design, replicated four times and repeated once. The irrigation rates were: 2.5, 5, 10 and 20 L/plant, while mulch types were: black plastic film, wheat straw and mulch-free control. Each treatment had 12 plants in 45 cmx45 cm planting holes spaced at 1.5 mx1.5 m and trellised onto posts and wires. The plants were subjected to different treatments from the fifth week after planting. Data were recorded bi-weekly and subjected to analysis of variance using the SAS software. The 16.8 laterals, leaf area of 122 cm2/leaf, and leaf biomass of 2.4 g/leaf for 20 L were significantly greater than the 11.3 laterals, leaf area of 106.5 cm2/leaf, and leaf biomass of 2.0 g/leaf for 2.5 L at P<0.05. Black plastic and wheat straw mulches significantly increased leaf biomass to 2.3 g/leaf. The 20 L significantly increased combined florals to 332 and dropped flowers to 241, compared to 250 and 171, respectively, for the 2.5 L. Black plastic mulch significantly increased combined florals to 326, dropped flowers to 235 and immature fruits to 76, compared to 263, 188, and 59, respectively, for 2.5 L. The 10 L and 20 L, as well as the black plastic and wheat straw effects were correspondingly not significantly different. When irrigating with at least 5 L, no additional benefit of mulching was observed, but mulch ameliorated drought stress when deficit 2.5 L was applied. The 10 L and the biodegradable wheat straw mulch are recommended for maximizing growth and flowering of purple passion fruits.
Irrigation rate and mulch type significantly affect some physiological processes of purple passion fruit (Passiflora edulis f. edulis Sims.) under drought stress.
(2011-12) Gaturuku, G. K.; Isutsa, D. K.; Aguyoh, J. N.; ; ;
Purple passion fruit (Passiflora edulis f. edulis Sims.) is an important fruit in the tropics, but its growth can be adversely affected by drought stress. This study evaluated effects of irrigation rate and mulch type on drought stress amelioration in purple passion fruits. The experiment was set up in a rain shelter in a randomized complete block design, replicated four times and repeated once. The irrigation rates were: 2.5, 5, 10 and 20 L/plant, while mulch types were: black plastic film, wheat straw and mulch-free control. Each treatment had 12 plants in 45 cmx45 cm planting holes spaced at 1.5 mx1.5 m and trellised onto posts and wires. The plants were subjected to different treatments from the fifth week after planting. Data were recorded bi-weekly and subjected to analysis of variance using the SAS software. The 16.8 laterals, leaf area of 122 cm2/leaf, and leaf biomass of 2.4 g/leaf for 20 L were significantly greater than the 11.3 laterals, leaf area of 106.5 cm2/leaf, and leaf biomass of 2.0 g/leaf for 2.5 L at P<0.05. Black plastic and wheat straw mulches significantly increased leaf biomass to 2.3 g/leaf. The 20 L significantly increased combined florals to 332 and dropped flowers to 241, compared to 250 and 171, respectively, for the 2.5 L. Black plastic mulch significantly increased combined florals to 326, dropped flowers to 235 and immature fruits to 76, compared to 263, 188, and 59, respectively, for 2.5 L. The 10 L and 20 L, as well as the black plastic and wheat straw effects were correspondingly not significantly different. When irrigating with at least 5 L, no additional benefit of mulching was observed, but mulch ameliorated drought stress when deficit 2.5 L was applied. The 10 L and the biodegradable wheat straw mulch are recommended for maximizing growth and flowering of purple passion fruits.
Response of strawberry quality and profitability to farmyard manure and triple super phosphate under tropical high altitude conditions
(2011) Odongo, T.; Isutsa, D. K.; Aguyoh, J. N.; ; ;
Quality of strawberries in the tropics is partly limited by poor soil fertility, while profitability of different nutrient management strategies has not been established. The present study determined the effect of 0, 18, 36, and 54 t/ha farmyard manure (FYM) and triple super phosphate (TSP), equivalent to 0, 17, 34 and 68 kg/ha phosphorus (P) on quality and profitability of strawberries. The study was done in three seasons on field 3 of Tatton farm-Njoro, Kenya. The design was split-plots embedded in randomised complete blocks, replicated three times. The FYM and TSP were broadcasted to main plots and sub-plots, respectively. Each treatment had 10 plants, spaced at 0.3 m x 0.45 m in 0.6 m x 1.5 m plots, mulched with black polyfilm and irrigated with drip lines. Berry fruit size, brix index and storage life were determined from 26 to 42 weeks after planting (WAP). Profitability was calculated using berry yield-income and input-costs at the end of the study. Results varied depending on response variable. High FYM and TSP significantly (P < 0.05) increased fruit size, but lowered storage life. High FYM significantly lowered brix index. Low FYM plus moderate P significantly lowered fruit size. Thus, 54 t/ha FYM plus 34 kg/ha P and 36 t/ha FYM plus 17 kg/ha P are recommended for large-sized and sweetest, long-storing berries, respectively. Manure alone increased profitability more than TSP alone. Highest FYM and TSP did not always result in highest profitability. The relationship between treatments and profitability was sigmoid, and dependent on site and season. Thus, profitable strawberry mineral nutrition packages will have to be developed for each site and season in Kenya.