Bread wheat is one of the most important staple crops in Ethiopia and it is largely produced by smallholder farmers in the highlands of the country. Its productivity is, however, very low below the world average mainly due to the dwindling of soil productivity and depletion of soil fertility as the result of complete removal of crop residues as well as abandoning of crop rotation and organic matter application. Hence, a 3 years experiment was conducted to study the productivity improvement of bread wheat through crop rotation and organic manure application in degraded crop fields of Ethiopian highlands. Both at station and on-farm sites, factorial combinations of five crop rotations (R1+ = bread wheat–clover–potato, R2+ = clover–bread wheat undersowing lupine–potato, R3+ = potato–clover–bread wheat, R4+ = bread wheat undersowing lupine–potato undersowing lupine–bread wheat and R5+ = lupine–potato undersowing lupine–bread wheat) and four manure application rates [M1 = control/without manure, M2 = 2.5 t ha−1 Sesbania green manure (SGM), M3 = 5 t ha−1 fresh cattle manure (FCM) and M4 = 2.5 t ha−1 SGM + 5 t ha−1 FCM] were laid out in a randomized complete block design with four replications. Crop rotation treatments with plus sign (+) indicated that crop residues and/or green manure of preceding crops were incorporated into the soil. Sole bread wheat crop (R1) without manure application (M1) in the first year (2013) was considered as the control and baseline of the study. Results of the study clearly showed that the interaction of R3+ and M4 in 3 years period (2013–2015) enabled to recover the highest grain productivity of bread wheat from 0.95 and 0.69 to 4.83 and 4.14 t ha−1 with the percentile increments of 408.42 and 500.00% at station and on-farm sites, respectively. Thus, long-term application of organic manure with moderate quantity and incorporation of crop residues in pragmatic crop rotation of a vigorous legume before wheat have great potentials for recovering the productivity of bread wheat in degraded crop fields.

Leaf pubescence is widespread among higher plants. In bread wheat, a relationship was found between this trait and the efficiency of photosynthetic processes and productivity. In this work, we established the chromosomal localization of the gene for leaf pubescence introgressed from Triticum timopheevii into a bread wheat line 821 and studied its expression in the genetic background of two wheat cultivars differing in genetic control and phenotypic expression of pubescence. To obtain quantitative characteristics of pubescence in cultivars and hybrid populations, the LHDetect2 program was used, which makes it possible to estimate the length and number of trichomes on a leaf fold. A genetic analysis showed the dominant inheritance of the gene. Monosomic analysis F2 was used to establish chromosome localization and investigate the expression of the gene in cultivars Saratovskaya S29 (S29) and Diamant 2 (Dm2). As a result, the gene Hltt, introgressed from T. timopheevii, was identified and localized in the distal region of the long arm of 5A chromosome for the first time. In both F2 populations, the gene reduced the density of trichomes and formed long trichomes, uncharacteristic for the two recipient cultivars S29 and Dm2. A larger number of long trichomes was formed in the genetic background of S29, which carry the bread wheat gene Hl1 and Hl3 for leaf pubescence, than in Dm2. Development of substitution and isogenic lines with the fragment of introgression carrying the gene Hltt will allow determining function and assessing the adaptive significance of the gene more precisely.

Genetic improvement along with widened crop base necessitates for the detailed understanding of the genetic diversity and population structure in wheat. The present investigation reports the discovery of a total of 182 alleles by assaying 52 simple sequence repeats (SSRs) on 40 genotypes of bread wheat. Unweighted neighbour-joining method grouped these genotypes into two main clusters. Highly heat tolerant and intermediate tolerant cultivars were grouped in the same cluster, whereas remaining genotypes, particularly sensitive ones, were assigned different cluster. Similarly, the entire population was structured into two sub-populations (K = 2), closely corresponding with the other distance-based clustering patterns. The marker-trait association was discovered for four important physiological parameters, viz. canopy temperature depression, membrane thermostability index (MSI), normalized difference vegetation index and heat susceptibility index, indicating for heat stress (HS) tolerance in wheat. Both general and mixed linear models of association studies during 2017 and 2018, revealed the association of SSR markers, wmc222 (17.60%, PV) and gwm34 (20.70%, PV) with the mean phenotypic value of MSI. Likewise, SSR markers barc183, gwm75, gwm11 and cfd7 revealed a unique relationship with four selected physiological traits. Candidate genes discovered using in silico tools had nine SSR markers within the genic regions reported to play a role in heat and drought stress responses in plants. The information generated about these genic regions may be explored further in expression studies in-vivo to impart HS tolerance in bread wheat.

Seed priming is a pre-sown treatment and it is often used to improve the performance of plants in any environment, especially germination. In the current study, various concentrations of nitric oxide (NO) were used to evaluate its role for the induction of physiological variations within seven different wheat (Triticum aestivum L.) genotypes. Two experiments were conducted during 2013 and 2014 and the data were statistically analysed for significance. All these genotypes after treatment with sodium nitroprusside (SNP) as NO donor at 10−4 and 10−5 M concentrations were sown following randomized complete block design with triplicates in the fields of District Muzaffarabad, Pakistan. The concentration of NO at 10−4 M showed promising results and most of the studied characters were found improved compared to control. Wheat varieties primed with 10−4 M SNP showed highest germination speed and germination percentage. NARC-2011 and Uqab-2002 showed much improvement in physiological attributes at both concentrations of NO priming. However, Uqab-2002 and Punjab-2011 showed a significant increase in chlorophyll contents and leaf moisture content with 10−4 and 10−5 M SNP priming compared to control. Highest relative water content was observed within unprimed Lasani, whereas the relative injury was found to be decreased at 10−4 M SNP primed Faisalabad-2008. Wheat varieties Punjab-2011 and Faisalabad-2008 showed the highest increase in grain yield and biological yield by 10−4 M SNP. Hence, it is concluded that sowing of crops after priming at 10−4 M NO concentration can improve the germination, biochemistry and physiology that ultimately lead to an increase in crop yield.

Effective in-season weed management options are limited for organic cereal farmers. Two alternatives to current farmer practices are improving efficacy of physical weed control through use of interrow cultivation or increasing the competitive ability of the crop through elevated seeding rates and more uniform spatial planting patterns. It is unknown how these two methods affect yield, quality, and economic returns. Field experiments were conducted in the northeast United States to determine whether the yield gain from increased weed control from these contrasting weed management strategies resulted in increased net returns and how these different systems affected grain quality. Wheat was planted at two seeding rates (400 and 600 plants m−2), in three row spacings (11, 18, and 23 cm). A fourth crop arrangement that approaches a more uniform spatial distribution through a combination of drilling and broadcasting seed was included. For weed control, treatments received tine harrowing. Wheat sown in wide rows also received interrow cultivation. Each system was sown in the presence and absence of condiment mustard, which was sown as a surrogate weed. Increased seeding rate reduced weed density 64% compared to a crop-free check and 30% compared to regional farmers' practices of 18-cm rows and 400 plants m−2. Increased seeding rates lowered grain protein 5% compared to standard seeding rates. Wide rows, in combination with interrow cultivation, reduced weed density 62%, increased yield 16%, and net returns 19% compared to regional organic practices. Significant increases in grain N were limited to weed-free plots. While increased seeding rates improved weed suppression, the high input cost of organic seed make this an unsatisfactory alternative to interrow cultivation and current farmer practices, as yield would need to be. 15 t ha−1 higher at elevated density to offset the extra cost of seed.

A participatory plant breeding (PPB) program involving the French farmers' association ‘Réseau Semences Paysannes’ and the French National Agricultural Research Institute (INRA) at Le Moulon was initiated in 2005. In the process of designing the breeding scheme, we evaluated the impact of farmer selection at an early stage (F2) on bread wheat cross progeny populations. The objectives were to characterize the effect of farmer selection, to evaluate the impact of farmer selection on intra-varietal diversity, to provide farmers with relevant information that they can use to improve their selection practices. Early selection was found efficient for some traits and for some of the 35 F2-derived F3 families. For traits of interest such as thousand kernel weight or grain weight per spike, when the response was significant, it was always positive. For most of the traits studied, the among-family genetic variance increased after selection while the average within-family genetic variance decreased. This study provides the first quantitative results for this PPB program and information that will help optimize it in the future.

Dwarfing genes play an important role in improving yield and adaptability of wheat cultivars in most production environments. Understanding the allelic distribution at dwarfing loci is very important for any wheat-breeding programmes. In this study, we reported the allelic constitution at microsatellite locus Xgwm261 and the two major height-reducing genes Rht-B1 and Rht-D1 among a set of 56 bread wheat cultivars and nine landraces, based on diagnostic polymerase chain reaction assays. With respect to Rht-B1, 37% of the accessions carried the dwarfing allele Rht-B1b, while at Rht-D1, only one accession carried the dwarfing allele Rht-D1b. The allelic state at Rht8 was assayed indirectly by genotyping for the linked microsatellite locus Xgwm261. About 26% of the accessions carried the 192 bp allele (linked with Rht8 gene in some cases), whereas 35 and 12% genotypes carried 165 and 174 bp allele at the microsatellite locus Xgwm261. Cultivars released from 1980 onwards increasingly carried either Rht-B1b or Rht8. This information should allow for a more rational use of this collection for the purpose of wheat improvement in Turkey.