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Changing climates and frequent spells of drought have increased the risk of crop failure, especially in arid and semi-arid regions, thus multiplying the vulnerability of food-insecure populations. The exogenous application of potassium (K) can potentially ameliorate the adverse effects of drought in maize by maintaining cell osmotic potential and turgidity, provided its optimum doses are applied. The present experiment comprised two maize cultivars, viz. Islamabad Gold (drought tolerant) and Azam (drought susceptible), grown under well-watered (80% water-holding capacity (WHC)), mild drought (60% WHC) and severe drought (40% WHC) conditions. Different doses of K, viz. 0%, 1% and 2%, were also tested to screen out the most superior concentration. Drought stress markedly reduced root and shoot lengths (25% and 16%, respectively) along with their dry weights (20% and 10%, respectively). Moreover, a substantial reduction in leaf relative water content (RWC) (24%), stomatal conductance, transpiration and photosynthesis rates, chlorophyll pigments a, b and total chlorophyll contents (31%) were recorded, compared with well-watered conditions. However, foliar application of K2SO4 at 2% concentration outperformed other doses by improving growth attributes, RWC (10%), total chlorophyll (9%) and proline (12%) under severe drought conditions. Our findings confirmed the effectiveness of foliage-applied K2SO4 in ameliorating drought effects in rainfed maize; however, more doses and sources of K could be tested for developing it as a potent source to cope with water stress.

This study demonstrates for the first time that resistance to different root lesion nematodes ( P. neglectus and P. penetrans ) is controlled by a common QTL. A major resistance QTL ( Rlnnp6H ) has been mapped to chromosome 6H using two independent barley populations. Root lesion nematodes (Pratylenchus spp.) are important pests in cereal production worldwide. We selected two doubled haploid populations of barley (Igri × Franka and Uschi × HHOR 3073) and infected them with Pratylenchus penetrans and Pratylenchus neglectus. Nematode multiplication rates were measured 7 or 10 weeks after infection. In both populations, continuous phenotypic variations for nematode multiplication rates were detected indicating a quantitative inheritance of resistance. In the Igri × Franka population, four P. penetrans resistance QTLs were mapped with 857 molecular markers on four linkage groups (2H, 5H, 6H and 7H). In the Uschi × HHOR 3073 population, eleven resistance QTLs (P. penetrans and P. neglectus) were mapped with 646 molecular markers on linkage groups 1H, 3H, 4H, 5H, 6H and 7H. A major resistance QTL named Rlnnp6H (LOD score 6.42-11.19) with a large phenotypic effect (27.5-36.6 %) for both pests was mapped in both populations to chromosome 6H. Another resistance QTL for both pests was mapped on linkage group 5H (Igri × Franka population). These data provide first evidence for common resistance mechanisms against different root lesion nematode species. The molecular markers are a powerful tool for the selection of resistant barley lines among segregating populations because resistance tests are time consuming and laborious.

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Sugar beet is the most important sugar crop that can be grown commercially in a wide variety of temperate regions. The beet sugar industry in the tropical and subtropical regions, which are mostly developing countries is growing as an important component of sugar production. A field experiment was conducted at Delta Sugar Company Research Farm, El-Hamool, Kafr El-Sheikh, Egypt to evaluate the response of sugar beet varieties to inter-and intra-row distances. The analysis of variance (ANOVA) revealed significant effects of inter-and intra-row distances on all studied traits, i.e., sucrose content (Pol%), Na%, K%, α-amino-N%, quality index (Qz)%, root yield (RY), recoverable sugar (RS)%, recoverable sugar yield (RSY), sugar loss (SL)% and sugar loss yield (SLY) either in one or both growing seasons except for the effect of inter-row planting distances on Na% and loss sugar yield in both growing seasons. The results revealed that increasing the inter-row planting distance from 50 to 60 cm led to a significant reduction in sucrose content, Na%, RY, RS% and RSY. However, increasing the inter-row planting distance from 50 to 60 cm is associated with a significant reduction in the Qz%, RS%, SL% and SLY. Increasing the intra-row planting distances from 10 to 15 cm led to a significant reduction in sucrose%, Na%, Qz% and RS%. Additionally, significant variations in all studied traits were observed among varieties.The interactions between the studies factors and varieties exhibited significant effects on all studied traits. Planting the variety Garrot at 15 and 50 cm intraand inter-row distances produced the highest Qz%, RY and RSY. The lowest SLY resulted from planting the sugar beet variety Husam at 10 and 60 cm intra-and inter-row planting distances. The results of the present study of great importance for a sustainable production of sugar beet in Egypt.