| dc.description.abstract | Experiments were conducted between October 2004 and June 2.05 at KAlUNational
Potato Research Center (NPItC) "Tigeni", to determine the effects of storage
conditions (light and temperature) on seed and ware potato (Solanum tuberosum L.) quality during storage and to investigate the use of gibberrelic acid (G.A3) in dormancy breaking of I major potato varieties. In seed potato experiments, treatments included: three varieties ('Tigoni', 'Asante' and 'Dutch Robyjn'), two temperature levels; low temperature (4°C) and ambient temperature (16-23°C; and three light levels; diffused light (612.2 Kw), direct light (1376 Kw) and dark (8 Kw) conditions for a period of 12 weeks. The effect ofG.A3 in dormancy breaking was investigated with five varieties ('Tigoni', 'Asante', 'Dutch Robyjn', 'Kenya Karibu' and 'Kenya Sifa'). The varieties were subjected to four doses of GA3concentration (O, 10, 20 and 30 ppm) and placed in a diffused light store (DLS) for 12 weeks or in pit for 2 weeks. Observations were made on weight loss (percentage), number of sprouted tubers (percentage), number of sprouts per tuber, length of the longest sprout, sprout vigor, potato tuber moth incidence (percentage), tuber rotting (percentage), and sprouting capacity.
The ware potato experiments involved use of four potato varieties; 'Tigoni',
'Asante', 'Dutch Robyjn' and 'Kenya Sifa'. These were subjected to low temperature (4°C)
and ambient temperature (16-23°C) in a naturally ventilated dark store (NVS) for a period
of 8 weeks. All treatments were arranged in a factorial arrangement in a randomized
complete block design (RCBD) with four replicates. The parameters recorded were; total
weight loss, dry matter (D M) content, potato tuber moth (PTM) incidence(%), number of
sprouted tubers (%) and tuber rotting (percentage). Tuber stored in dark conditions had a lower weight loss than tubers stored in direct light conditions. 'Dutch Robyjn' lost the lowest weight of 4.9 %.Tubers stored in the dark developed high number of long sprouts. High number of sprouts per tuber (6.3) were observed in 'Asante' while 'Dutch Robyjn' had the lowest number of sprouts (3.8). Potato tuber moth incidence was in higher percentage in the direct light storage. It is therefore suggested that farmers should adopt storage of seed tubers in diffused light store to allow formation of short firm sprouts and reduce weight loss. High weight loss was observed in tubers stored under ambient conditions. 'Tigoni' lost the highest weight of 11.5%. No sprout growth and development was recorded in the tubers stored in the low temperatures. However, at ambient temperatures, all tubers were sprouted by the end of the storage period. Potato tuber moth incidence was only observed under ambient conditions on 'Tigoni' and' Asante'.
The ware potato results indicated that low weight losses were recorded from
tubers stored in the low temperature condition. The highest dry matter content of 23.9%
was recorded in 'Dutch Robyjn'. High potato tuber moth incidence was noted under
ambient storage. Rotting of tubers was only reported in 'Kenya Sifa' variety. Tubers
stored under ambient conditions attained 100% sprouted tubers except in 'Kenya Sifa'.
In GA3 experiment, dormancy period was reduced to three weeks in all
genotypes except 'Kenya Sifa', which sprouted after four weeks following GA3
treatments in DLS. Increasing GA3 concentrations increased sprouting (%), number of
sprouts per tuber, and sprout length and vigor score. In the pit, the potato seed tubers
sprouted within the two weeks of storage. Except for 'Kenya Sifa', GA3 had no effect on
sprouting and vigor score; however, it increased number of sprouts per tuber and sprout
length, under pit conditions. Increase in GA3 concentration led to increase in rotting at 30
mg kg" of GA3 for 'Tigoni', 'Kenya Sifa' and 'Kenya Karibu' genotypes, under DLS. It
is suggested that lower levels of GA3 up to 20 mg kg" should be adopted for
promotion of sprouting of potato seed tubers, | en |
