Abstract
Adaptive research was carried out on quality protein maize (QPM) in the coastal region
with a view to combating climatic vulnerability. The location of the study was greater
Barisal region covering districts of Patuakhali, Barguna and Barisal in Bangladesh during
the period from November 2012 to April 2015. The specific objectives of the study were to
ascertain the productivity of QPM in the coastal region to ensure safer harvest by replacing
traditional cultivation practice which would provide dietary supplement for malnourished
coastal community. In order to achieve the goals four QPM cultivar/lines (QPM-1, QPM10, QPM-18 and BARI hybrid maize-5) with three mulches (water hyacinth, rice straw and
ridge) and a control were used in the adoptive trial in three consecutive years under
conservation tillage condition to replace the traditional system of agriculture, so as to
ensure a second crop in the dry season. To address the adoptability of QPM under
conservation agriculture a standard questionnaire was administered among the farmers.
The data were collected from a sample of 90 randomly selected farmers in the study area.
Water hyacinth and rice straw mulches were used at the rate of 10 t ha-1. Water hyacinth
and rice straw mulches reduced soil temperature fluctuations and retained higher soil
temperatures at the early hours in the diurnal cycles and that were the decisive factors
for the rapid development of QPM plants. Mulches also decreased salinity level and
conserved greater amount of soil moisture. The highest amount of photosynthetically
active radiation (PAR) was intercepted by QPM canopy grown under water hyacinth and
rice straw mulched plots and the lowest in the control plots. Water hyacinth and rice straw
mulches had significant promotive effects on root length, plant height, dry matter (DM)
accumulation in root, shoot, leaf and cob. Mulches also significantly influenced the leaf
area index (LAl), specific leaf area (SLA), specific leaf weight (SLW), crop growth
rate (CGR) and relative growth rate (RGR). All mulches lowered root/shoot ratio in all
the developmental stages. Un-mulched soil significantly decreased the SPAD value,
chlorophyll a and chlorophyll b contents due to the increased salinity and accompanying
proline contents. Salinity and low soil moisture reduced the grain number per cob,
shortened life span (7-10 days) and yields in un-mulched QPM plants. Mulching increased
soil organic matter and decreased pH. Water hyacinth retained higher amount of nutrients
and increased protein content in QPM grain. Of the three districts average maximum grain
yield was 9.8 t ha-¹ with water hyacinth mulch in BARI hybrid maize-5 cultivar under zero
tillage and minimum was 3.3 t ha-¹ in control with QPM-10 under conventional tillage. The
highest gross margin (73392 Tk. ha-¹) was recorded from zero-tillage + water hyacinth and
the lowest (3737 Tk. ha-¹) from tillage + no-mulch condition. Poor marketing channel was
the major obstacle for maize/QPM expansion in coastal region. The fallow lands in the
coastal areas during the dry season can effectively be brought under QPM cultivation with
organic mulch cover, where salinity and other hazards would have little or no effect on its
productivity. Thus organic mulches with conservation tillage practice can make maximum
yield of QPM and safer harvest in coastal region in combating climatic vulnerability.