Effects of Calcium, Potassium and Water Stress on Growth, Yield and Quality of Different Tomato Varieties in Mandera County, Kenya
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Date
2020
Authors
Mulyungi, Peter Syengo
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Tomato (Solanum lycopersicum) is well known regarding its quality and nutritional
value all over the world but imbalances of fertilizer nutrients severely affect its
quality. If exposed to stresess, either biotic (organisms) or abiotic (arising from
imbalances of environmental factors) e.g water; growth and productivity is affected.
The objective of this study was to determine the effects of calcium and potassium on
yield and quality responses in two different tomato varieties under different moisture
regimes. The effects of three watering regimes (daily, thrice and twice a week),
fertilzer application rates as treatments at Ca 0 Kgha-1, 25 Kgha-1,50 Kgha-1, K, 0
Kgha-1, 25 Kgha-1 and 50 Kgha-1 applied independently were used on two tomato
varieties (Riogrande and Rionex) in randomized complete block design (RCBD)
with split-split plot arrangement; with watering regimes as main plot, tomato
varieties as sub plot, while fertilizer rates were within the sub-sub plot. The
treatments were replicated three times. Tissue analysis was done after completion of
the growing cycle on leaves and fruits to determine the calcium and potassium
concentration levels at National Agricultural Laboratories in Nairobi in these organs.
Two-way analysis of variance (ANOVA) using GenStat 15.1 Version was used to
test levels of significance due to treatments and their interactions. Where there were
significant differences, Fischer‟s Protected LSD test was performed to separate the
treatment means at 5% probability level.Riogrande variety had both longest
internode length and fresh fruit weight of 4.89 cm and 416.g respectively. Watering
regimes had no significant effects (P≤0.05) on internode length with 5.04 cm
(optimal regime) being the longest and 4.31 cm the shortest (twice a week), while
plant height of 60.18 cm was the longest and 51.41 cm the shortest (optimal and
minimal watering regimes respectively). The heaviest fruit was 446.5 g and 328.5 g
the lightest under moderate and minimal watering regimes.Water stress led to the
highest percentage of floral abortion as well as blossom end rot score on the two
varieties in both sites of 56.42 % and 3.19% respectively. Application of fertlizers
at 50 kgha-1, Ca and 50 kgha-1,K elicited the highest growth and yield with
interactions between varieties and watering regimes observed on plant height,fruit
set and fruit weight.These treatments also exhibited the lowest percentages of floral
abortion. Fertilizer treaments did not significantly increase both the number of
flower and fruit set in both sites but there were differences which could be
attributed to positive repsonse for both Ca and K. Fertilizer application rate at 25
Kgha-1 K and 50 Kgha-1Ca had the least incidences of blossom end rot score in both
sites on the two tomato varieties with the highest score observed on control
treaments. Both tomato varieties had an increasing trend on flower abortion as
fruiting season advanced which was contrary to trend on blossom end rot. Both Ca
and K were more partitioned in shoot than in fruits. Futhermore, both tomato
varieties demonstrated resistance to fruit cracking. From the results, the common
physiological incidences affecting tomatoes can be reduced by manipulating the
watering regimes, Ca and K levels. It would be interesting to find out the optimal
ratio of these elements in control of these physiologal/diseaseincidence
Description
A Thesis Submitted in Partial Fulfillment of the Requirements for the Award
of the Degree of Master of Science in Agronomy in the School of Agriculture
and Enterprise Development of Kenyatta University
Keywords
Water Stress, Tomato Varieties, watering regimes, Mandera County, Kenya