Recycled hydroponic solutions used for growing crops can accumulate allelochemicals that inhibit plant growth. We applied alternating current electrodegradation (AC-ED) to fresh nonrenewed nutrient solutions (i.e. solutions remaining unchanged throughout the culture period) and once-used nonrenewed solutions (i.e. solutions that had been used for a previous culture) for detoxifying autotoxic chemicals. Four experiments were conducted in which lettuce plants were grown in different nonrenewed solutions treated with AC-ED and in renewed solution that was not treated with AC-ED. Renewed solution (50% ‘Enshi’ solution) was changed at 14-day intervals. In fresh starting solutions, no substantial difference was found in shoot fresh weight (SFW) between renewed and AC-ED-treated nonrenewed solutions at different intervals (experiment I) and frequencies (experiment III), but notably, the lowest yield was recorded in non-renewed solution. In contrast, in the case of once-used nonrenewed solution, weekly (experiment II) and thrice-weekly and continuous (experiment IV) AC-ED application showed significantly higher SFW compared to values for other solutions, and the lowest value was also found in nonrenewed once-used culture solution. Therefore, we recommend the application of AC-ED to non-renewed solution either thrice weekly or continuously for efficient detoxification of accumulated allelochemicals to improve the growth, yield and quality of lettuce under two or more successive cultivations in recycled hydroponics.
The experiment comprised of 10 treatments, such as T0: Control condition; T1: All chemical fertilizer as recommended dose; T2: Cowdung as recommended dose; T3: Compost as recommended dose; T4: ½ Cowdung + ½ Compost; T5: Cowdung + Compost; T6: Cowdung + ½ Chemical fertilizer; T7: Compost + ½ Chemical fertilizer; T8: Cowdung + Compost +½ Chemical fertilizer and T9: ½ Cowdung + ½ Compost + ½ Chemical fertilizer. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. Data on different growth characters and yield were recorded. Among the treatments all chemical fertilizers as recommended dose (T1) and cowdung + compost + ½ chemical fertilizer (T8) were found superior considering all yield contributing characters and yield. At 30 (Days after Sowing) DAS, the longest plant was recorded from T8 (27.93 cm), while the shortest plant was found in T0 (23.13 cm). At 50, 70, 90 DAS and harvest the longest plant was recorded from T1 (52.13 cm, 82.13 cm, 85.93 cm and 95.21 cm), whereas the shortest plant was obtained from T0 (41.14 cm, 65.84 cm, 70.77 cm and 76.00 cm). At 30, 50, 70, 90 DAS and harvest the maximum number of tillers hill-1 was recorded from T1 (2.00, 5.64, 6.93, 6.15 and 5.78), whereas the minimum number was found in T0 (1.33, 2.87, 4.20, 3.94 and 3.72). The longest spike (19.86 cm), maximum number of spikelets spikes-1 (20.33), maximum number of filled grains spike-1 (34.00), highest grain yield (3.71 t ha-1) and highest straw yield (5.78 t ha-1) was attained from T1 and the shortest spike (14.33 cm), minimum number of spikelets spikes-1 (14.18), minimum number of filled grains spike-1 (21.53), lowest grain yield (2.06 t ha-1) and lowest straw yield (4.49 t ha-1) was recorded from T0.DOI: http://dx.doi.org/10.3329/jesnr.v6i1.22066 J. Environ. Sci. & Natural Resources, 6(1): 203-208 2013
Soil salinity is an increasing problem in the world and main obstacle to agricultural productivity especially in areas where irrigation is necessary. It adversely affects plant growth and development. Adoption of salt tolerant variety is more important here and so screening of salt tolerant germplasms is essential. For this reason, a germination test under salinity and a hydroponic experiment were conducted at Plant Physiology Laboratory, Department of Crop Botany, Bangladesh Agricultural University, Mymensingh to investigate the effect of NaCl on germination, morphological characters and growth of sorghum seedlings. The experiment comprised of two levels of NaCl concentration viz. Control (without NaCl and EC 1.36 dSm−1 in hydroponic culture) and 80 mM NaCl and five sorghum germplasms viz. BD 700, BD 703, BD 707, BD 710 and BD 726. There were 10 (5×2) treatments in a completely randomized design (CRD) with three replications. Results showed that germination percentage, hypocotyls and epicotyls length, root and shoot length, leaf length, leaf sheath length, fresh and dry mass production were influenced by NaCl stress. However, among tested germplasms, BD 707 showed the best performance considering the seedlings growth, germination percentage and other parameters. BD 710 and BD 703 showed the highest sensitivity to NaCl stress based on the above parameters studied. These results suggested that sorghum is able to grow with moderate salinity.J. Bangladesh Agril. Univ. 16(1): 67-72, April 2018
A study was carried out to ascertain the impact of planting time and weeding schedule on the yield and quality of baby corn. The trial included three planting times viz. 15 November, 15 December and 14 January and five levels of weeding regime viz. no weeding, two hand weeding (HW) at 15 days after sowing (DAS) and 30 DAS, herbicide pendimethalin @ 2.5 L ha -1 (pre-emergence) + one HW at 30 DAS, herbicide pyrazosulfuran-ethyl @ 2.0 L ha -1 (post-emergence) + one HW at 30 DAS and combined herbicide of pendimethalin + pyrazosulfuran-ethyl. The maximum cob yield with husk (11.93 t ha -1 ) and cob yield without husk (3.07 t ha -1 ) were obtained from the 15 December sowing with the application of pendimethalin followed by pyrazosulfuran-ethyl. Plants sown on 15 December with the application pyrazosulfuran-ethyl with one HW at 30 DAS gave the highest protein content in cobs (20.20%), while the leaf protein content showed the highest result (18.70%) in the plants sown on 15 December with no weeding. Therefore, it can be concluded that the baby corn might be planted on December 15 with the combined application of pendimethalin + pyrazosulfuran-ethyl herbicides and pyrazosulfuran-ethyl + one HW at 30 DAS for maximum cob yield and protein content, respectively.
Three separate field experiments were conducted to exploit biomass yield potential of dhaincha (Sesbania species) by different cultural practices. A total of six accessions from three Sesbania species, viz. S. bispinosa (#05, 71, 77 and 109), S. cannabina (#28) and S. sesban (#81), were used as experimental materials. Experimental treatments were population densities, viz. 180, 240 and 300 plants m-2; sowing dates, viz. 30 April, 15 May, 30 May and 15 June, and fertilizer doses, viz. 0 (without N/control), 10, 20 and 30 kg N ha-1. All the experiments were designed following randomized complete block design with three replications. Experiments on population density and sowing dates were conducted in control condition (without any fertilizer application). The N-fertilizer was applied as top dress at 30 days after sowing (DAS) and crops were harvested at 60 DAS. The maximum biomass (10.07 t ha-1) was obtained from 240 plants m-2. At 30 April sowing, plants produced the tallest height (199.69 cm), widest base diameter (1.02 cm), highest fresh weight (62.07 t ha-1) and biomass yield (14.73 t ha-1). There were no significant differences in biomass yield and yield contributing descriptors between 20 and 30 kg N ha-1. Among the species, S. bispinosa was the best performer in terms of biomass yield and yield contributing descriptors. It may be concluded that S. bispinosa (accession #71) could be cultivated with the population density 240 plants m-2, at 30 April, without any fertilizer application. In case of later sowing/cultivation, the 20 kg N ha-1 could be applied for the maximization of biomass yield.
Drought management is a major challenge under changing climate conditions, and improvement in drought tolerance is the ultimate goal for scientists working in varietal development. Drought stress has a severe effect on the growth and development of sugar beet seedlings, leading to an enormous reduction in total biomass accumulation. Polyamines (PAs) are low-molecular weight positively charged aliphatic polycations, and putrescine (Put) is the central product in PA biosynthesis pathway and also acts as a precursor of Spd and Spm, which are widely used for stress management in various crop. Due to their chemical structure, PAs are polycationic in nature, which modulate the ion balance in cells and bind with polyanionic molecules like DNA, RNA, proteins, or membrane, thus preventing macromolecule and cell degradation membranes under adverse conditions. The binding properties exhibit the ROS scavenging capacity of PAs, which confers the antioxidative role that can prevent the cell from being damaged by lipid peroxidation and ROS generation. Therefore, the application of Put on sugar beet may be a helpful tool for stress mitigation that increases the yield and quality without any harmful effect on plants and the environment.
