Authors:I. Prasad, N. Kulshreshtha, A. R. Chinchmalatpure, and D. K. Sharma
Soil salinity is one of the major environmental constraints in increasing agricultural crop production, especially wheat production in India. Screening of diverse germplasm in representative growing conditions is prerequisite for exploring traits with stable expression imparting salinity tolerance. A study was undertaken during 2011–2012 for characterizing wheat germplasm in three environments representing growing conditions of crop in Northern parts of India, estimating inter-relationship among traits and evaluating stability of trait conferring salinity tolerance. Significant value of mean square for observed trait across the environments signified presence of large variability in genotypes. Significant yield reduction was recorded in almost all genotypes in saline environment compared to non-saline condition. Ratio of potassium and sodium ion in leaf tissue (KNA); a key salt tolerance traits was found to be significantly correlated with biomass, SPAD value and plant height. Due to the presence of significant genotype × environment interaction (G × E) for KNA, additive main effect and multiplicative interaction (AMMI) model was utilized to study stability of KNA among genotypes and environments. IPCA1 and IPCA2 were found to be significant and explained more than 99 per cent of variation due to G × E. KRICHAUFF was having maximum trait value with specific adaptation while DUCULA 4 and KRL 19 were having general adaptability. AMMI2 biplot revealed high stability of Kharchia 65 and KRL 99 across environments. E1 (timely sown, non-saline soil) recorded maximum site mean while E2 (timely sown, sodic soil) was having minimum interaction with genotypes (AMMI1 = 1.383). Thus, our studies suggest that AMMI model is also useful for estimating adaptability of traits other than yield utilized for breeding salt tolerant wheat varieties.
Authors:S.L. Krishnamurthy, S.K. Sharma, R.K. Gautam, and V. Kumar
Effects of salinity on correlation, path and stress indices, yield and its components were studied in a set of 34 promising rice genotypes collected from various national and international organizations. These genotypes were evaluated in a randomized complete block design with three replications during the wet seasons (kharif) of 2009 and 2010 in normal (ECiw ∼ 1.2 dS/m) and salinity stress (ECiw ∼ 10 dS/m) environments in micro plots at Central Soil Salinity Research Institute (CSSRI), Karnal, India. Grain yield per plant showed positive significant association with plant height, total tillers, productive tillers, panicle length, and biological yield per plant and harvest index under normal environment, whereas grain yield showed positive significant association with biological yield and harvest index under salinity stress. These results clearly indicate that selection of high yielding genotypes would be entirely different under normal and saline environments. The stress susceptibility index (SSI) values for grain yield ranged from 0.35 (HKR 127) to 1.55 (TR-2000-008), whereas the stress tolerance index (STI) values for grain yield ranged from 0.07 (PR 118) to 1.09 (HKR 120). The genotypes HKR 120, HKR 47 and CSR-RIL-197 exhibited higher values of stress tolerance index (STI) in salinity. Under salinity, negative and significant association was shown by SSI and grain yield in contrast to positive and significant association shown by STI and grain yield. These associations could be useful in identifying salt tolerant and sensitive high yielding genotypes. The stress susceptible and stress tolerance indices suggest that the genotypes developed for salinity tolerance could exhibit higher tolerance, adaptability and suitability. Harvest index and biological yield traits emerged as the ideal traits for improvement through selection and could be used to increase the rice productivity under saline stress environments.
Authors:K. Makhlouf, L. Hamrouni, M. L. Khouja, and M. Hanana
Bayuelo-Jiménez , J. S. , Debouck , D. G. and Lynch , J. P. ( 2002 ): Salinitytolerance of Phaseolus species during germination and early seedling growth . — Crop Sci. 42 : 1584 – 1594 . http://dx.doi.org/10.2135/cropsci2002
Synthesis of flavonoid compounds in plants is associated with their response to environmental stress; however, the way in which the transcription of the relevant structural genes is regulated in stressed plants is still obscure. Transcription of the ‘early’ flavonoid synthesis genes Chi-1 and F3h-1 in the wheat coleoptile was investigated by quantitative real-time PCR in seedlings exposed to 100 mM or 200 mM NaCl. Under mild stress, transcript abundance of both Chi-1 and F3h-1 was increased significantly after six days of exposure. Under severe stress, the level of transcription was the same or even lower than that seen in nonstressed seedlings. In non-stressed conditions, the transcription patterns of Chi-1 and F3h-1 were quite distinct from one another, whereas under stress they became similar. An observed alteration in structural genes regulation mode under stress conditions may optimize flavonoid biosynthesis pathway to produce protective compounds with maximum efficiency.