Statistical analysis of wheat yield under drought conditions
Seven statistical procedures including; simple correlation, path analysis, multiple linear regression, stepwise regression, factor analysis, principal components and cluster analysis were used to study the relationship between wheat grain yield and its components under drought conditions of Saudi Arabia. Results revealed that number of spikes/m2, 100-grain weight, weight of grains/spike and biological yield were the most effective variables influencing grain yield. Based on the results, it is reasonable to assume that high yield of wheat plants under drought conditions could be obtained by selecting breeding materials with high spikes/m2, 100-grain weight, weight of grains/ spike and biological yield. 
Yield of Wheat in the United Kingdom: Recent Advances and Prospects
From 1948 to the present, wheat (Triticum aestivum L.) yields in the UK have increased by an average of 110 kg ha−1 each year. This rate of increase has been at least maintained in recent years. The greater yields have been associated with the adoption of cultivars of shorter stature, which are resistant to lodging and reach anthesis ≈1 wk earlier than old cultivars. In the last two decades, most of these cultivars have carried the rht D1b dwarfing gene. The full yield benefits from modern cultivars have depended on high rates of N fertilization and the use of herbicides and effective fungicides. Data from recent trials with candidate cultivars and F1 hybrids suggest that further genetic gain in yield will be achieved during the next decade. Improved crop protection through chemicals may also enable farmers to obtain greater yields. In the longer term, substantial genetic gain in yield may be achieved if breeders are able to produce cultivars with faster growth rates and greater biomass at maturity. One way to achieve this would be to modify the photosynthetic enzyme rubisco so that its oxygenase activity is reduced. However, cultivars with potentially faster growth rates would require even more N fertilizer if their greater yield potential is to be realized. 
Markers associated with a QTL for grain yield in wheat under drought
Drought is a major abiotic stress that adversely affects wheat production in many regions of the world. The objective of this study was to identify quantitative trait loci (QTL) controlling grain yield and yield components under reduced moisture. A cross between common wheat cultivars ‘Dharwar Dry’ (drought tolerant) and ‘Sitta’ was the source of one hundred twenty-seven recombinant inbred lines evaluated for two-seasons in a field under differing soil moisture regimes in Ciudad Obregon, Sonora, Mexico. An SSR/EST-STS marker map was constructed and a grain yield QTL on the proximal region of chromosome 4AL was found to have a significant impact on performance under reduced moisture. This region was associated with QTL for grain yield, grain fill rate, spike density, grains m−2, biomass production, biomass production rate, and drought susceptibility index (DSI). Molecular markers associated with these traits explained 20, 33, 15, 23, 30, 26, and 41% of phenotypic variation, respectively on chromosome 4A. Microsatellite locus Xwmc89 was associated with all significant QTL covering a 7.7 centiMorgans (cM) region and generally explained the greatest proportion of phenotypic variation. The alleles associated with enhanced performance under drought stress were contributed by Dharwar Dry. Microsatellite marker wmc89 may be useful for marker assisted selection to enhance drought tolerance. 
Effects of Foliar Application of Boron (B) on the Grain Set and Yield of Wheat (Triticum aestivum L.)
Aims: The objective of this study was to evaluate the effect of foliar application of boron (B) on the grain set and yield of wheat (cv. Shatabdi).
Study Design: The experiment was designed with six boron treatments, arranged in a randomized complete block design (RCBD) with three replications.
Place and Duration of Study: The field trial was conducted at Bangladesh Agricultural University (BAU) farm, Mymensingh during 27 November 2010 to 24 March 2011.
Methodology: The B treatments were (i) B control, (ii) soil application of B, (iii) seed priming into boric acid solution, (iv) foliar spray of B at primordial stage of crop, (v) foliar spray of B at booting stage and (vi) foliar spray of B at primordial and booting stages. The rate of B for soil application was 1.5 kg B ha-1 from boric acid (17% B) and the rate for each foliar spray was 0.4% boric acid solution. Seed priming was done by soaking wheat seeds into 0.1% boric acid solution for 10 hours and then seeds were dried before sowing. Every plot received 115 kg N, 25 kg P, 75 kg K and 15 kg S per hectare from urea, TSP, MoP and gypsum, respectively.
Results: The treatment receiving foliar spray of B at both primordial and booting stages of the crop performed the highest yield (3630 kg ha-1) which was statistically similar with the yield recorded with foliar spray of B at booting or primordial stage of crop and with soil application of B before crop (wheat) was sown; all the yields were significantly higher over the yield noted with seed priming or control treatment. The control treatment (no B application) had the lowest grain yield (2600 kg ha-1) which was significantly lower than the yield observed with the seed priming treatment.
Conclusion: Wheat yield was affected due to grain set failure induced by boron deficiency and it was possible to overcome this element deficiency by soil application at 1.5 kg B ha-1 or foliar application of 0.4% boric acid solution at primordial or booting stage of crop. 
Enhancement of Plant Growth and Yield of Wheat (Triticum aestivum L.) under Drought Conditions Using Plant-growth-promoting Bacteria
To reduce negative effects of drought on plants, the use of plant growth- promoting rhizobacteria (PGPR) is an effective way to investigate that. The aim of the present study was to assess the bacterial characteristics Bacillus subtilis, Bacillus cereus, Pseudomonas koreensis, Pseudomonas fluroscence, and Enterobacter cloacae as growth, IAA production, phosphate solubilization, seed germination under different concentrations of polyethylene glycol (PEG 6000), and their efficacy of single or dual inoculation with two superior strains in lyzimeter experiment for improving growth and yield of sensitive variety of wheat (Triticum aestivum L.) cv. Sids 1 under different stress irrigation water 100, 70 and 35% of field capacity. Among the tested strains only 2 strains B. subtilis and P. koreensis showed a stable growth even in the maximum 40% PEG concentration. Also, P. koreensis produced the highest amount of IAA (1.84 µg ml-1), and solubilise maximum amount of P (1.59 µg ml-1), and improved seed germination at 30% PEG concentration. On the other hand, in gnotobiotic sand system experiment, PGPR increase growth dynamics as well as proline content and root colonisation of wheat plants over uninoculated control under drought-stressed conditions.
In lyzimeter experiment, single and dual inoculation treatments showed a significant increase of physiological and biochemical parameters of the plant under different drought stress treatments. Also, maximum increase 29.08 % in ascorbate peroxidase and 27.38% in catalase activities due to dual inoculation treatments T12 (Inoculation with B. subtilis + P. koreensis and irrigated at field capacity 35%), with respect to the corresponding unstressed control T10 (Inoculation with B. subtilis + P. koreensis and irrigated at field capacity 100%). Also, significant increase in grain yield, straw yield, biological yield and harvest index were observed under different drought stress. These results may be related to increase uptake of water and nutrients in wheat plant and reflected in better plant growth and yield. 
 Leilah, A.A. and Al-Khateeb, S.A., 2005. Statistical analysis of wheat yield under drought conditions. Journal of Arid environments, 61(3), pp.483-496.
 Austin, R.B., 1999. Yield of wheat in the United Kingdom: recent advances and prospects. Crop Science, 39(6), pp.1604-1610.
 Kirigwi, F.M., Van Ginkel, M., Brown-Guedira, G., Gill, B.S., Paulsen, G.M. and Fritz, A.K., 2007. Markers associated with a QTL for grain yield in wheat under drought. Molecular Breeding, 20(4), pp.401-413.
 Fakir, O. A., Rahman, M. A. and Jahiruddin, M. (2016) “Effects of Foliar Application of Boron (B) on the Grain Set and Yield of Wheat (Triticum aestivum L.)”, Journal of Experimental Agriculture International, 12(2), pp. 1-8. doi: 10.9734/AJEA/2016/24286.
 Omara, A. E.-D. and Elbagory, M. (2018) “Enhancement of Plant Growth and Yield of Wheat (Triticum aestivum L.) under Drought Conditions Using Plant-growth-promoting Bacteria”, Annual Research & Review in Biology, 28(6), pp. 1-18. doi: 10.9734/ARRB/2018/44181.