Abstract
Field studies were carried out during the period from January 2015 to September 2017
under partial shade conditions of a multistrata 'Living Plant Gallery' established at
Bangladesh Agricultural University, Mymensingh, for year round vegetable and seed
production following RCBD design. The first experiment with 3 varieties of okra under
partial shade and non-shade (sunny) condition showed significant difference in seed
yield having the highest 2.72 t ha-¹ in variety United Seed (Inbred) followed by 2.14 t ha1 in Lal Teer (Hybrid) and the lowest (1.55 t ha-¹) in BARI Dherosh-1, while in terms of
shade conditions, the yield was 2.16 t ha¹ in non-shade and 1.28 t ha-1 in partial shade
condition. This result clearly showed significant reduction in yield under partial shade
condition compared to non-shade condition, probably due to depletion of nutrients and
shading effect along with tree roots' influence. Therefore, before subsequent
experiments, nutrient depletion in soil collected from experimental plots under
continuous okra production was studied. The results of this study showed that total
nitrogen and soil organic matter were significantly reduced especially under tree shade
condition. Therefore, the depleted nutrients were compensated through additional
nutrient supply with 10 to 20% increased rate in subsequent experiments with the
selected United Seed (Inbred) variety of okra. Following this, better results in vegetative
growth with both fruit and seed yield were observed. Finally, sowing in end of
September, January and April, significant differences in vegetable and seed yield was
observed. The highest number (12.92) of fruits per plant was observed in September
sowing followed by 9.28 in January sowing with the lowest (5.26) in April sowing. In
terms of shade conditions, the fruit number was 9.55 in non-shade and 8.09 in partial
shade condition. However, fruit length was similar between the treatments having 11.96
cm in April sowing followed by 11.45 cm in January sowing with the lowest (11.30 cm)
in September sowing. The fruit length was 11.87cm in non-shade and 11.27cm in partial
shade condition. In contrary, the highest fruit diameter (2.05 cm) was observed in
September sowing followed by 2.01 cm in January sowing with the lowest (1.74 cm) in
April sowing, while it was same (1.93 cm) in both the conditions. The vegetable yield
was the highest (8.27 t ha-¹) in September sowing followed by 7.18 t ha¹ in January
sowing with the lowest (4.34 t ha-1) in April sowing, while under 2 conditions, it was
7.65 t ha-¹ in non-shade and 5.31 t ha-¹ in partial shade condition. The seed yield was the
highest (0.96 t ha¹) in January sowing followed by 0.84 t ha-¹ in April sowing with the
lowest (0.82 t ha-¹) in September sowing. Seed yield was 0.97 t ha-¹ in non-shade and
0.71 t ha-¹ in partial shade condition. However, okra seeds physically appeared very
healthy in partial shade condition having remarkable yield. This study also showed that
okra could be produced both for vegetables and seeds throughout the year, in spite of
having remarkable reduction in vegetable yield in April sowing, while January sowing
was found more effective in seed production. The results presented clearly indicate that
both vegetable and seed yield of okra showed better results in non-shade condition
compared to partial shade. However, year round production of okra under partial
shade condition of multistata garden always showed good crop growth and economic
yield having a sustainable multistrata production for both economic and
environmental benefits.