Effects Of Calcium, Potassium And Water Stress On Growth, Yield And Quality Of Different Tomato Varieties In Mandera County, Kenya

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