Forgoing the fallow in Bangladesh’s stress-prone coastal deltaic environments: Effect of sowing date, nitrogen, and genotype on wheat yield in farmers’ fields.

Working with 64 farmers ineight production environments, we examined yield response to three genotypes, BG25 and BG27 (with salinity - and heat - tolerant traits) and BG21 (local check), across a gradient of sowing dates, grouped as ‘early’ (sown before 15 December) and ‘late’ (after 15 December), under 0, 100 and 133 and 0, 67 and 100 kg N ha-1 for early- and late-sowing groups, respectively. <p> Across environments and genotypes, yield ranged from 2.11 to 4.77 t ha-1(mean: 3.9 t ha-1) under early-sowing, and from 0.83 to 4.27 t ha-1(mean: 2.74 t ha-1) under late-sowing. Wheat performance varied with environment (1.68 - 4.77 t ha-1 at 100 kg N ha-1across sowing groups); the lowest yields found where early sowing was delayed and soil salinity levels were elevated. Small but significant (P less than 0.001) yield differences (0.22 t ha-1) were found between 100 and 133 kg N ha-1 for the early-sowing group, though no difference was found between 67and 100 kg N ha-1 for late-sowing. Combining early- and late-sowing groups, significant environment x N rate and sowing-group x N rate interactions (both P less than 0.001) for 100 kg N ha-1 indicated the importance of site-and time-specific N management in these stress-prone environments. </p> <p> Considering all cultivars and environments, ECa at sowing, flowering and grain filling negatively correlated with yield (r = - 0.50, - 0.59 and - 0.54, all P less than 0.001). Correlations with ground water depth at flowering and grain filling were negative and significant, but less pronounced in the context of farmer-managed irrigation scheduling. Despite putative stress-tolerance traits in two of the three entries, no genotypic yield differences were found under early-sowing, though s mall differences (less than 0.19 t ha-1) were observed with late sowing. Agronomic fertilizer-N efficiency (AE-N) was consistently higher for 100 than 133 and 67 than 100 kg N ha-1 for early- and late-sowing. The marginal economic value of N application followed similar trends, indicating that rates of at most 100 and 67 kg N ha-1 are favorable for sowing before or after December 15th. </p>

Bibliographic Details

Main Authors:	Timothy J. Krupnik, Zia Uddin Ahmed, Jagadish Timsina, Md. Shahjahan, A.S.M. Alanuzzaman Kurishi, Azahar A. Miah, B.M. Saidur Rahman, Mahesh K. Gathala, Andrew J. McDonald
Other Authors:	Ashok Rai
Language:	English
Published:	CIMMYT Research Data & Software Repository Network 2014
Subjects:	Agricultural Sciences, wheat, genotypes, fallow, nitrogen fertilizers, sowing date, coastal area, Bangladesh,
Online Access:	https://hdl.handle.net/11529/11084
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