dc.description.abstract | Two experiments were cond~c~ed between August, 1990
and April, 1991, at the Faculty of Agriculture Field
Station, Kabete Campus, Universi~y of Nairobi to study the
effects of nitrogen rates (0, :"3, 26 and 52 kgN/ha) and
deflowering on vegetative growth, leaf yield and quality
of Gynandropsis gynandra L. The experiments were setup in
a randomized complete block design with eight factorial
treatments and three replications. Quality of the leaves
was evaluated by analysing for ascorbic acid, ~-carotene
and total phenolics contents. Storage stability of the
leaves was evaluated under two storage conditions (shelf
and refrigerated) and two packaging methods (perforated
and non-perforated polythene bags) by analysing for losses
in ascorbic acid and moisture and colour change over time
of storage.
.s Plants top-dressed with N and deflowered had
increased vegetative growth and significantly higher mean
weekly and cumulative leaf yields. Nitrogen application
also tended to extend the harvest duration. Increasing N
rate significantly decreased the content of ascorbic acid
in leaves, although the leaves generally had high contents
on dry matter basis. Deflowering, and the two-way
interactions between N, deflowering and plant age had
significant effects on ascorbic acid contents in the
leaves during the second experiment. Nitrogen application
.ocfo
a~d deflowering had no significant effects on ~he contents
of B-carotene and total phenolics in the leaves. The
contents of ascrobic acid, B-carotene and total phenolics
were significantly affected by plant age. The content of
ascorbic acid increased with plant age whereas that of
total phenolics decreased. The content of B-carotene was
highest at the 7th week of growth after which it
decreased.
The non-perforated polythene bags showed effective
control of moisture loss from leaves despite the storage
condition, and made the leaves retain ascrobic acid
better than the perforated ones. Temperature had a
dominant effect on colour deterioration with refrigerator
condition having very slow deterioration. Shelf storage
could be effective for storage upto 2 days and
refrigerator up to 12 days. | en |