The influence of defoliation and deblossoming on growth and runner production in strawberry (fragaria ananassa dutch) in Kenya

Abstract

Asexual propagation of strawberry in Kenya is difficult due to the limited runner production by the available cultivars. Lowe runner production occurs because of the short day condition, which induces continuous flowering. A few growers depend on imported propogative material from temperate countries while others depend oncrown-dividing the existing plants during planting. Physical manipulations of parent such as deblossoming, defoliation or a combination of both were conducted to invstigage the improvement of runnering in 3 strawberry cultivars. Defoliatin alone promoted runner production in Turft during 1980 short rains and in Turft and Tioga during 1981 long rains season. Defoliation alone or in combination with deblossoming failed to increase runner production in Aiko in both seasons. Deblossoming alone failed to stimulate runner production in Tioga and Aiko during 1980 short rains seasons and in Turft plants produced more runner plants than any other treatment in the 3 cultivars in both seasons. The number of runner plants decreased in deblossomed Tioga and Aiko plants during 1980 short rains when compared to the control plants. Deblossoming increased branch crown development in Turft and Tioga plants but failed to incrase the number of branch crowns in Aiko plants in both seasons. Defoliation alone decreased the number of branch crowns in Turft and Tioga during 1980 short rains season and decreased branch crown development only in Tioga during 1981 long rain season. Defoliated Turft and Aiko plants were not significantly different in branch crowns development form their control plants during 1981 long rains season. Defoliated-deblossomed and defoliated plants were not significantly different in braaaanch crown development in Aiko and Turft in both seasons. Defoliation alone or in combination with deblossoming decreased petiole length in all cultivars when compared to the control plants during 1980 short rains season. Deblossming alone increased petiole length only in Turft and failed in Tioga and Aiko during 1980 short rains season. There was no significant difference between the control and the treated Aiko plants in petiole and runner lengths in 1980. In both seasons leaf area increased in defoliated and defoliated – deblossomed Turft and Tioga plants. Deblossomed and control plants die not show any significant difference in leaf area in all cultivars in both seasons. Deblossoming alone or in combination with defoliation did not retard the production of new flowers in the three cultivars in both seasons. However, more flower clusters were produced in 1980 short tains season than during the 1981 long rains season. In 1980 short rains season more flower clusters were removed in Tioga than in Turft or Aiko plants. In both seasons, low flower production was associated with higher number of runners, more runner plants and large leaves.