Rice growth and yield response to salinity can be influenced by the duration and the timing of salt stress. The present study tested the effects of saline water irrigation from vegetative growth to maturity on rice growth and yield and ion concentrations in the straw and root and related them to changes in soil salinity and soil solute potential. The treatments consisted of five levels of saline water irrigation (electrical conductivity ~0.25 (control), 4, 6, 8, and 10 dS m^-1) with two rice cultivars (BRRI dhan67 and BRRI dhan99) grown in pots in a rain shelter. Grain weight per pot, dry straw weight, and root weight were significantly reduced with increasing water salinity, but BRRI dhan99 was less affected. With prolonged saline water irrigation, salt concentration increased in the soil and lowered the soil solute potential. Increased saline water induced higher concentrations of Na⁺ in the straw (527–1200 mmol kg^-1 at 4–10 dS m^-1) relative to the root. By contrast, higher Cl^- concentrations accumulated in the root than in the straw. The decrease of K⁺ in the straw and root for increasing salinity was inconsistent, but the Na⁺/K⁺ ratio sharply increased in the straw with higher water salinity. The increased Na⁺/K⁺ explained most grain weight loss due to higher salinity (R² = 0.93) followed by Na⁺ (R² = 0.87) and Cl^-1 (R² = 0.53). We conclude that the prolonged saline water irrigation has a cumulative effect on root zone salinity and solute potential that depresses grain yield in rice by increasing the Na⁺/K⁺ ratio in plants.

Haor areas are the most vulnerable areas in Bangladesh. Rice is the major food crops grown in the hoar areas despite natural threats during the harvesting period. The appropriate size of the mechanical harvester is one of the solutions to mitigate the natural calamities and labor shortage in the hoar regions. This paper examines the technical and financial performance of a small combine harvester with the aim of determining its market viability in Bangladesh's hoar areas. Based on the field test and economic assessment, data on field power, forward speed, fuel consumption, time allocation in harvesting, hire fee, and payback period of machine were determined. The study showed that the operation by width was 10% less than the operation by longitudinal. Plot length and area of the plot should be more than 25m and 400 m2, respectively, to operate the small combine harvester at full capacity. Harvesting speed ranged from 0.63-0.90 km hr-1, and actual field capacity ranged from 0.03-0.05 ha hr-1. Fuel consumption ranged from 25-32 L ha-1 due to slow cutting speed. The plant density was observed higher due to cultivating high yielding variety. The machine should be operated at a low speed, preferably walking speed, to avoid clogging in the conveying chain. The combine harvester has used 56% of the harvest time, and a remaining 44% for turning purposes and other inevitable uses. The small combine harvester recorded 1.12-1.40% loss of grain. However, grain damaged was not observed during harvesting. The small combine harvester becomes profitable for the investment cost of Tk 3,50,000 with a hiring rate of Tk 10,000 Tk ha-1 following 15 ha of harvesting area in a harvest capability of 0.04 ha hr-1. This machine is suitable for a small size of land where larger sizes of machines are inaccessible. This would offer small entrepreneur different choices of paddy harvesting mechanization to encourage future adoption of enhanced innovations.