Low seed emergence rate, poor seedling growth and low survival rate of winter rice due to cold spell are very common in Bangladesh. Pre-sowing seed priming could be a viable approach to overcome this problem. A laboratory screening of different priming agents was conducted at the Agro Innovation Laboratory, Department of Agronomy, Bangladesh Agricultural University in November 2018. The experiment comprised two factors. Factor A includes five rice varieties, namely i) BRRI dhan28 ii) BRRI dhan29 iii) BRRI dhan36 iv) BRRI dhan55 and v) Hybrid SL-8H; factor B includes 22 seed priming methods comprised different concentrations of NaCl, KCl CaCl2, CuSO4, ZnSO4, Na2MoO4, PEG and control (no priming). The experiment was laid out in a completely randomized design (CRD) with four replications. A positive influence of seed priming on seed emergence rate (%), germination time, seedling vigor and seedling growth (length and dry matter) was evident from this study. Among the priming agents, KCl and CaCl2 performed best; while priming with NaCl, Na2MoO4 and PEG showed no advantages over no priming for germination rate and seedling vigor & growth indices. In conclusion, pre sowing seed priming approach can be explored as a viable tool for increased seed germination and better seedling growth of winter rice under stress condition.
The residual effect of eight herbicides (pendimethalin, pyrazosulfuron-ethyl, butachlor, pretilachlor, orthosulfamuron, acetochlor + bensulfuron methyl, butachlor + propanil and 2,4-D amine) was applied in unpuddled transplanted aman rice in aa weedy and a hand weeded controls, was evaluated for succeeding crops viz. wheat, lentil and sunflower by following bioassay technique. A study was conducted at Bangladesh Agricultural University, Mymensingh from November 2013 to January 2014 after harvest of unpuddled transplanted aman rice. All herbicides were imposed as weed management practice of unpuddled transplanted aman rice during July to August 2013. The experiment was laid out in a randomized complete block design (RCBD) with three replications. As a consequence, the residual effect of those herbicides on the succeeding wheat, lentil and sunflower crops was evaluated in term of germination, leaf chlorophyll content, seedling shoot length and dry matter. The results showed that seedling germination of all these succeeding crops in the herbicide treated plots did not differ significantly from those of weedy and hand weeded control plots. Moreover, leaf chlorophyll content, seedling shoot length and dry matter of wheat, lentil and sunflower were not adversely affected by any of the herbicide treatments imposed in aman rice. It was concluded that herbicides used in unpuddled transplanted aman rice had no residual effect on the germination and leaf chlorophyll content, seedling shoot length and dry matter of the succeeding wheat, lentil and sunflower crops.
Transplanting of rice seedling on the puddle land is the principal system of rice cultivation. Water scarcity and labour shortage imposed a serious threat to the sustainability of rice culture under this popular method. In response to the increased labour scarcity and cost in Asia, many temperate countries switched to machine transplanting and tropical countries adopted wet direct seeding. This switch from puddle transplanting to other system substantially reduced the manual labour requirement in rice culture but contributed a little to the water saving. Recently developed dry direct seeded technology is efficient in reducing both labour and water requirement in rice culture. Wet direct seeding requires puddling of land while puddling is avoided in dry direct seeding. Dry direct seeded rice system contributes a lot to the reduction of greenhouse gas emission and arsenic accumulation. Therefore, considering the agro-climatic situation of the region, the appropriate rice establishment methods should be adopted for sustaining productivity with the minimum use of water and labour and also to protect health and environment.
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