Varietal Variation in Physiological and Biochemical Traits of Durum Wheat Genotypes under Salinity Stress

Background: Rapid global warming associated with abiotic stresses particularly salinity stress directly poses a major challenge to the present-day agriculture. Wheat is moderately sensitive crop that occupies the largest total harvested area among the cereals including rice and maize. Durum wheat is considered as a less tolerant to bread wheat, hence, the study aims to investigate the response of durum wheat genotypes under salinity stress. Methods: A randomised block design experiment involving five durum wheat genotypes viz; HI 8737, HD 4728, HD 4730, MACS 3972 and HI 8708 and two levels of salinity i.e. normal water (Control) and saline water (ECiw -10.0 dSm-1) was conducted with three replications during 2018-2019 and 2019-2020. The observations on different physico-biochemical parameters were recorded in roots as well as shoots at the vegetative stage. Result: Salinity of 10 dS m-1 water caused 26.36% reduction in the chlorophyll content in comparison to control. Among osmolytes, salinity stress caused dual response i.e. limits the accumulation of TSS in roots whereas it enhanced the TSS accumulation in shoot, while reverse trend was noted for proteins. Salt stress enhanced the accumulation of proline and antioxidative enzymes activities in both root and shoot in comparison to control.

Population Structure And Diversity Among Improved Cowpea Varieties From Senegal Based On Microsatellite Markers

Cowpea (Vigna unguiculata) is used in West Africa for both human consumption and animal feeding. Despite its importance, the production of the crop is hampered by biotic and abiotic constraints. To overcome these constraints, the Senegalese Institute of Agricultural Research (ISRA) has set up a breeding program since 1960 leading to the release of productive varieties. Information of the genetic diversity for these varieties could improve the effectiveness of further breeding programs. The objectives of this study was to assess the genetic diversity and the population structure of 11 cowpea improved varieties from ISRA collection. Twelve (12) polymorphic microsatellite markers were used and the analysis of genotypic data showed a total of 39 alleles ranging from 2 (SSR6288, SSR6311 and SSR6827) to 6 (SSR6807) per locus. Polymorphism rate ranged from 8.33% (Mougne and Kelle) to 58.33% (Mouride) with an average of 31.06%. Intra varietal genetic diversity was very weak (0.012 to 0.091). The genetic similarity revealed that Melakh and Pakau varieties were genetically the closest while Bambey 21 and Sam were the most distant. These results are confirmed by the dendrogram, which also showed that Thieye, Leona, Kelle, Sam, Mougne and Yacine varieties have a higher genetic stability than Lisard, Melakh, Pakau, Mouride and Bambey 21. Eighty-seven percent (87%) of the total variability was attributed to inter varietal variability while 17% was due to intra varietal variation. These results provide a better knowledge of genetic resources of cowpea varieties released and held by ISRA and constitute important input for further cowpea breeding programs.

Changes in physico-chemical and sensory fruit quality attributes of apricot during ripening

Varietal variation in apricot causes differential changes in fruit quality during ripening. A study was executed to evaluate the effect of apricot varietal variation on fruit physico-chemical and sensory attributes during fruit ripening. Fruits of two apricot cultivars, ‘Old Cap’ and ‘Red Flesh’ obtained from Baluchistan were monitored at ambient conditions (25 ± 2 °C and 60-65% RH) during fruit ripening for physico-chemical and sensory attributes. Irrespective to days at shelf during fruit ripening, fruits of ‘Red Flesh’ apricot exhibited significantly reduced fruit weight loss with greater fruit firmness, total soluble solids (TSS), total phenolic content (TPC), ascorbic acid and antioxidant scavenging activity (ASA) than ‘Old Cap’ apricot fruits. However, titratable acidity (TA) of ‘Old Cap’ apricot fruits remained significantly higher than ‘Red Flesh’ apricot fruits during ripening. At eating soft stage, sensory attributes including fruit pulp colour, taste, flavour and overall acceptability of ‘Red Flesh’ apricot fruits were superior to ‘Old Cap’ apricot fruits. In conclusion, ‘Red Flesh’ apricot showed better fruit physico-chemical attributes during fruit ripening and fruit sensory attributes at eating soft stage than ‘Old Cap’ apricot fruits.

Varietal variation and chromosome behaviour during meiosis in Solanum tuberosum

Naturally occurring autopolyploid species, such as the autotetraploid potato Solanum tuberosum, face a variety of challenges during meiosis. These include proper pairing, recombination and correct segregation of multiple homologous chromosomes, which can form complex multivalent configurations at metaphase I, and in turn alter allelic segregation ratios through double reduction. Here, we present a reference map of meiotic stages in diploid and tetraploid S. tuberosum using fluorescence in situ hybridisation (FISH) to differentiate individual meiotic chromosomes 1 and 2. A diploid-like behaviour at metaphase I involving bivalent configurations was predominant in all three tetraploid varieties. The crossover frequency per bivalent was significantly reduced in the tetraploids compared with a diploid variety, which likely indicates meiotic adaptation to the autotetraploid state. Nevertheless, bivalents were accompanied by a substantial frequency of multivalents, which varied by variety and by chromosome (7–48%). We identified possible sites of synaptic partner switching, leading to multivalent formation, and found potential defects in the polymerisation and/or maintenance of the synaptonemal complex in tetraploids. These findings demonstrate the rise of S. tuberosum as a model for autotetraploid meiotic recombination research and highlight constraints on meiotic chromosome configurations and chiasma frequencies as an important feature of an evolved autotetraploid meiosis.

A Study on the Effect of Storage of Betel Leaves at Ambient Temperature

A research study was conducted for studying the storage of Madras and Kolkata varieties of betel leaves under ambient temperature with different diffusion storage systems were observed for different treatments. In the treatment T1, the concentration of oxygen, O2 reduced to a minimum of 14.27 per cent and carbon dioxide, CO2 concentration increased to 4.80 per cent on the 14th day of storage in ambient condition (28°C). It was also reported that by the 14th day, betel leaves stored at ambient condition maintained satisfactory quality in the entire diffusion channel chambers. For the Kolkatta leaves the treatment T2, the concentration of O2 was reduced to 12.0 per cent and CO2 concentration increased to 7.87 per cent on the 18th day of storage. Compared to other treatments, the O2 concentration was found to be very low and CO2 concentration was high on the 18th day of storage in T2 diffusion channel. Similarly, on the 18th day, betel leaves stored at ambient condition maintained satisfactory quality in all the treatments. Hence, it is clear that from this present study, different varieties of betel leaves will have different rates of respiration for a particular size of the diffusion channel and temperature. In other words, varietal variation occurs concerning respiration rate under identical condition.

Inter- and intra-varietal variation in aerobic methane emissions from environmentally stressed pea plants

Environmental stress factors can influence methane (CH4) emissions from plants. There are a few studies on the interactive effects of stress factors on plant aerobic CH4, but none on the comparative evaluation of CH4 emissions between and among plant varieties. We examined the effects of temperature, UVB radiation, and watering regime on CH4 emissions from 10 pea (Pisum sativum L.) varieties first and then selected two varieties with the highest (237J Sundance; var. 1) and lowest (422 Ho Lan Dow; var. 2) emissions for further studies. Plants were grown in controlled-environment growth chambers under two temperature regimes (22 °C / 18 °C and 28 °C / 24 °C, 16 h light / 8 h dark), two UVB levels (0 and 5 kJ·m−2·d−1), and two watering regimes (well-watered and water-stressed) for 14 days, after one week of growth under 22 °C / 18 °C. Higher temperatures and water stress increased CH4 emissions, and increased emission was associated with stress. Pea varieties varied in growth and CH4 emissions; var. 1 was more stressed and had higher emission than var. 2. In the stressed variety, the water-stressed plants grown under higher temperatures at UVB5 had the highest CH4 emission, whereas the well-watered plants grown under lower temperatures at UVB5 had the lowest emission. We conclude that climatic stress conditions increase CH4 emissions, which vary with plant varieties.