S. M. Razvi

Resilience of cereal crops to abiotic stress: A review

In the last century, conventional selection and breeding program proved to be highly effective in improving crops against abiotic stresses. Therefore, breeding for abiotic stress tolerance in crop plants should be given high research priority as abiotic stresses are the main factor negatively affecting crop growth and productivity throughout the globe. Advancement in physiology, genetics and molecular biology, have greatly improved our understanding of plant responses to stresses. Many studies show that salt tolerance is tightly associated with the ability to maintain ion homeostasis under salinity. Na + transporter SKC1 unloads Na + from xylem; plasma membrane N + /H + antiporter SOS 1 excludes sodium out of cytosol, and tonoplast Na + /H + antiporter NHX 1 sequesters Na + into the vacuole. Silicon deposition in exodermis and endodermis of rice root reduces sodium transport through the apoplastic pathway. A number of transcription factors regulate stress-inducible gene expression that leads to initiating stress responses and establishing plant stress tolerance. Over expression of some transcription factors, including DREB/CBF and NAC, enhances salt, drought, and cold tolerance in rice. A variant of one of ERF family genes, Sub1A-1 , confers immersion tolerance to lowland rice. These findings and their exploitation will hold promise for engineering breeding to protect crop plants from certain abiotic stresses. Although, cereal crops are also quite sensitive to various abiotic stresses, hence in this short review, we will present recent progresses in adaptation of cereal crops to salinity, drought and cold tolerance are emphasized and the future potentials are highlighted. Keywords: Cereal crops, abiotic stresses, food insecurity, molecular breeding, quantitative trait loci (QTLs), salinity, water stress. African Journal of Biotechnology , Vol 13(29) 2908-2921

Screening of maize inbred lines under artificial epiphytotic conditions for Turcicum leaf blight (Excerohilum turcicum)

A study on reaction of ten inbred lines of maize to northern leaf blight mainly caused by Exserohilum turcicum (Pass) Leonard and Suggs, was conducted under artificial epiphytotics conditions in green house. Among 10 inbred lines evaluated, three were found moderately resistant viz, NAI-113, NAI-152 and NAI-137, five lines moderately susceptible viz, NAI-123, NAI-142, NAI-143, NAI-147 and NAI-116, and the rest two, W3 and W5 inbreds were severely affected by TLB and rated as susceptible. The lines identified to possess low disease severity score against Turcicum leaf blight in the present study could be used successfully in developing genotypes having desirable level of resistance in disease endemic areas to aim for sustainable productivity. Key words: Maize (Zea mays L.), northern leaf blight, inbred lines, screening.

Genetic effects of combining ability on forage quality traits and forage yield in diallel crosses of oats (Avena sativa L.)

Studies in oats (Avena sativa L.) were carried out to generate information on combining ability (general and specific), nature and magnitude of gene effects and heterosis for forage quality and yield. The experimental material comprised of 10 diverse parents and 45 F1 crosses (excluding reciprocals) generated through a 10 x 10 diallel mating design. Significant interaction between combining ability effects were observed for all the quality traits and yield. The estimates of additive variance were higher in magnitude than their corresponding dominance variance estimates indicating the role of additive gene action, except green forage yield and dry matter yield. The parent SKO-213 had highly significant and desirable GCA effects for crude protein content, SKO-210 for neutral detergent fibre, SKO-204 for acid detergent fibre, SKO-208 for crude fibre parent, SKO-207 for ash content and SKO-212 for both green forage and dry matter yields. Cross combinations viz., SKO-212 x SKO-213, SKO-204 x SKO-211, SKO-205 x Sabzaar, Sabzaar x SKO-212 and SKO-205 x SKO-211 exhibited high and desirable sca and heterobeltiosis effects simultaneously for all the quality traits, green forage yield and dry matter yield ha−1.