The effect of post-harvest ammonium sulphate application, planting time and sucker size on plant growth and yield of queen pineapple, ananas comosus
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Date
2013
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Publisher
University of Zululand
Abstract
Queen pineapple plant mortality as well as poor growth and development are some
of the major problems facing the Hluhluwe pineapple producers. Approximately 20%
of the plants do not produce fruit, due to mortality or poor growth. Queen pineapple
plantings are currently established from suckers taken from harvested plants. The
speed and development of suckers on the mother plant is not rapid enough to be
used as planting material at fruit harvest. Therefore, suckers are left to grow on the
mother plant for 6 to 8 months after harvesting the plant crop for the suckers to attain
a suitable size for planting. The aim of the study was to determine, under field
conditions, the effects and interactions of post-harvest ammonium sulphate fertilizer
application and the duration of sucker growth on the production and quality of
suckers as well as on the growth and development of subsequent plantings.
Post-harvest (NH4)2SO4 application had a significant influence on the percentage
increase in sucker fresh mass and length when interacting with the duration of
sucker growth on the mother plant. Growing suckers on the mother plant for up to 8
months, after the application of post-harvest (NH4)2SO4, produced more plantable
suckers than growing them for 6 or 10 months. Four sucker sizes were produced
namely, size 2, 3, 4 and 5. Grading suckers by length produced more plantable
material than grading by fresh mass.
Plant gain in fresh mass and stem diameter, was positively correlated with sucker
size and post-harvest (NH4)2SO4 application. At 2 months after planting, 6 symptoms
that could lead to plant mortality were identified namely, wilted plants, plants toppling
over, plants planted doo deep, plants growing slowly, plants with funnel rot and plant
that dying back. The total percentage of these plant mortality symptoms was 19.6%
in the March planting, 26% in the May planting and 33.1% in the August planting.
Wilted plants and plants planted too deeply formed a greater proportion of the plants
affected by the mortality symptoms in all the plantings. Some of the plants affected
by the mortality symptoms recovered and grew into healthy plants, whereas some
grew slowly and some died.
Sucker size and post-harvest (NH4)2SO4 application had no significant effect on
levels of mealybug, Dymicoccus brevipes and red mite, Dolichotetranychus
floridanus infestation.
Post-harvest (NH4)2SO4 application influenced the percentage of P and K in leaves in
the May and August planting. Sucker size had an influence on N percentage in the
March planting only. Plants established from smaller sucker sizes had a significantly
higher N percentage than plants established from bigger sucker sizes.
Sucker size had an influence on flowering failure. Plants established from a smaller
sucker size had a higher percentage of flowering failure than the plants established from a bigger sucker size. The March planting had a higher percentage of plants that
failed to produce flowers after flower induction than the May and August planting.
The total percentage of plants that failed to flower in the March planting was 15.92%
(7.39% due to plant mortality symptoms and 8.53% due to unknown causes), in the
May planting it was 6.02% (4.69% due to plant mortality symptoms and 1.33% due to
unknown causes) and in the August planting it was 7.56% (5.39% due to plant
mortality symptoms and 2.17% due to unknown causes). Plant mortality symptoms
were the main cause of flowering failure in the May and August plantings. Postharvest
(NH4)2SO4 application had a significant effect on wilted plants in the March
planting and on natural flowering in the August planting. Flowering failure resulted in
fruit yield loss.
Fruit yield was more influenced by the sucker size than by post-harvest (NH4)2SO4
application. There was a positive correlation between sucker size and fruit yield. Fruit
size was used to determine the influence of post-harvest (NH4)2SO4 application and
sucker size on the external and internal quality of the fruit. Post-harvest (NH4)2SO4
application had a significant influence on fruit length, inter-fruitlet cracks, winter
speckle occurrence and total soluble solids. Sucker size was found to have an
influence on the number of fruitlet spirals, fruit length, crown fresh mass, fruitlet
cracks, winter speckle occurrence and total soluble solids. Black spot, nectary duct
and internal browning infestation were influenced by the number of days the fruit
were kept in storage after harvesting. Post-harvest (NH4)2SO4 application and sucker
size had no significant influence on black spot, nectary duct and internal browning
infestation.
Eight months after fruit harvest in the March and May planting, evaluation was done
to determine the effect of post-harvest (NH4)2SO4 application, sucker size and
mortality symptoms on sucker yield. Plants established from bigger suckers
produced longer and heavier suckers as well as a higher number of plantable
suckers than plants established from smaller suckers. Healthy plants produced
longer and heavier suckers as well as a higher number of plantable suckers than
plants that were affected by the mortality symptoms.
Plants treated with post-harvest (NH4)2SO4 produced quality planting material in
terms of fresh mass and length. Leaving the suckers to grow for 8 months after fruit
harvest produces more plantable material. Planting the planting material obtained
from plants treated with post-harvest (NH4)2SO4 increased fruit yield and profit.
Description
Submitted in partial fulfillment of the requirements for the degree Master of Science in the Department of Agriculture, Plant Production, in the Faculty of Science and Agriculture at the University of Zululand, South Africa, 2013.
Keywords
Ananas comosus, Planting material quality, Plant growth and mortality, Flowering