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This study was conducted on 94 Frieswal (5/8 Holstein Friesian 3/8 Sahiwal) crossbred bulls of three different grades, categorized based on their semen freezability visualising Group 1 (consistently freezable semen producer bulls, N 5 11), Group 2 (inconsistent freezable, N 5 16) and Group 3 (Non freezable, N 5 67). Each group was further divided into two classes that is young (up to 30 months) and adult (31 to 70 months) bulls depending upon their age. Sperm morphology was studied by using the eosin-nigrosin staining technique. Bulls age significantly (P , 0.01) affected semen quality and sperm morphology. In adult bulls, semen volume, mass activity and sperm concentration were 36%, 17.56% and 19.6%, respectively, higher than young. Initial progressive motility (%) and livability showed significant (P , 0.01) improvement with the advancement of age (43.37 6 1.21 and 67.71 6 1.11, respectively, in young; 53.02 6 1.11 and 74.17 6 1.03, respectively, in adult). In young bulls, sperm head, mid piece, tail abnormality and total abnormal sperm percent (12.38 6 0.92, 4.87 6 0.24, 11.01 6 0.60 and 28.26 6 1.34, respectively) were 1.85, 1.27, 1.20 and 1.44 folds higher than that of their mature stage (6.69 6 0.64, 3.82 6 0.32, 9.14 6 0.64 and 19.66 6 1.31, respectively). Significant reduction (P , 0.01) in micro cephalic sperm, free heads, bent mid piece, looped mid piece and proximal protoplasmic droplets were observed at mature age as compared with their younger stage. In bulls of consistent freezing category, abnormal sperm heads significantly decreased from 4.40 6 0.31% to 3.28 6 0.02% on maturity. Similarly, in inconsistent freezing grade bulls sperm head abnormality (9.28 6 0.75% to 5.13 6 1.20%) and total abnormal sperm percent (24.89 6 1.43 to 18.73 6 3.40) was decreased over the age. On the contrary, in non-freezing category bulls' sperm morphology did not show significant (P . 0.05) improvement with age advancement, rather some abnormalities like long slender head, under developed/deformed head, abaxial implantation of mid piece, double mid piece, stump tail and distal protoplasmic droplets tend to increased significantly (P , 0.05) with age of bulls. Results indicated that in potential Frieswal bulls semen quality and sperm morphology were improved from young to mature stage, where as, in poor quality (non-freezing) semen producer bulls neither the morphology nor the semen quality showed any improvement with maturity. It was recommended that crossbred bulls producing more than 25% morphologically abnormal sperms in young age (below 30 months) along with poor progressive motility (,50%) and low sperm concentration (,1000 million/ml) need immediate culling with out any expectation of further improvement in semen quality with age advancement.Keywords: Sperm abnormality, Frieswal crossbred bull, Sperm morphology, Bos indicus 3 Bos taurus Implication Assessment of sperm morphology is one of the most important aspects for semen evaluation and successful fertilisation. High percentage of morphologically abnormal spe...

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The leaf water potential, gas-exchange parameters and chlorophyll fluorescence were evaluated in five common oil palm (Elaeis guineensis Jacq.) tenera hybrids 913X1988, 1425X2277, 748X1988, 7418X1988, and 690X1988 under water deficit with an aim to identify hybrids which can cope up better under such conditions and understand possible differences among hybrids in relation to the physiological mechanisms triggered by water deficit. Our findings indicate oil palm hybrids 913X1988, 1425X2277, and 7418X1988 maintained higher leaf water potentials than the other hybrids. Hybrids 7418X1988 and 1425X2277 recorded lower stomatal conductance after water deficit, which resulted in higher intrinsic water-use efficiency. The excess light energy produced due to decreased photosynthesis in 7418X1988 and 690X1988 hybrids under water deficit was dissipated as heat by higher nonphotochemical quenching. The maximum efficiency of photosystem II was not affected, even after withholding water for 24 days, suggesting an increased efficiency of photoprotection mechanisms in all these oil palm hybrids.

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Abiotic stresses, including drought, extreme temperatures, salinity, and waterlogging, are the major constraints in crop production. These abiotic stresses are likely to be amplified by climate change with varying temporal and spatial dimensions across the globe. The knowledge about the effects of abiotic stressors on major cereal and legume crops is essential for effective management in unfavorable agro-ecologies. These crops are critical components of cropping systems and the daily diets of millions across the globe. Major cereals like rice, wheat, and maize are highly vulnerable to abiotic stresses, while many grain legumes are grown in abiotic stress-prone areas. Despite extensive investigations, abiotic stress tolerance in crop plants is not fully understood. Current insights into the abiotic stress responses of plants have shown the potential to improve crop tolerance to abiotic stresses. Studies aimed at stress tolerance mechanisms have resulted in the elucidation of traits associated with tolerance in plants, in addition to the molecular control of stress-responsive genes. Some of these studies have paved the way for new opportunities to address the molecular basis of stress responses in plants and identify novel traits and associated genes for the genetic improvement of crop plants. The present review examines the responses of crops under abiotic stresses in terms of changes in morphology, physiology, and biochemistry, focusing on major cereals and legume crops. It also explores emerging opportunities to accelerate our efforts to identify desired traits and genes associated with stress tolerance.