Journal of Crop Science and Biotechnology

Cucumber is a subtropical vegetable sensitive to high and low root temperature. Additionally, mycorrhiza with beneficial effect on plant growth can increase plant tolerance to stress. This experiment was carried out as a factorial design based on CRD to study the effect of mycorrhiza density (0, 1,000 spores and 2,000 spores) on cucumber (Cucumis sativus cv. Super N3) under low (15°C), high (35°C), and optimum (25°C) temperature root zones. The result showed that low and high root zone temperatures decreased shoot and root fresh weight, chlorophyll content, and antioxidant activity compared to optimum temperature, while the phenols of shoot and NR activity increased in low and high temperature, respectively, as compared to optimum temperature. Both mycorrhiza inoculation (1,000 and 2,000 spores) increased shoot and root fresh weight while mycorrhiza with 1,000 spores increased antioxidant activity and phenol content and NR activity had no influence by mycorrhiza symbiosis. Mycorrhiza inoculation increased SPAD value at optimum temperature. FV/FM reduced by mycorrhiza with 2,000 spores at low and high temperature stress. Total phenol content increased at all temperature levels by mycorrhiza inoculation. Mycorrhiza with 1,000 spore increased antioxidant activity of leaves at all root zone temperatures. NR activity increased with both mycorrhiza inoculation at optimum temperature and decreased at high root zone temperatures. In general, our results showed that mycorrhiza symbiosis had a desirable effect on cucumber culture at low and high root zone temperatures.

In wheat, the increase of yield and stability associated traits can be achieved by combining parents containing the stay-green trait and favorable alleles for grain yield. The aim of this work was to analyze the genetic dissimilarity between wheat lines from stay-green and synchronized maturation groups and elite cultivars. Moreover, to propose promising combinations seeking the selection of high-grain yield and high bread-making quality genotypes containing stay-green trait. The experiment was conducted in a randomized block design with three replications in 2003, 2004, and 2005, using sister-lines with the presence and absence of stay-green trait and elite cultivars. Genetic variability exists among wheat strains from the synchronized stay-green maturation group and elite cultivars. Genotypes of maturation group stay-green obtained an average performance superior to the synchronized group. Crosses between stay-green lines and the CEP 29 and BRS 177 cultivars are promising in the selection of genotypes carrying the stay-green trait with high yield and bread-making quality.

Biomass partitioning was studied in sunflower (Helianthus annuus L.) inbred lines and their hybrids differing in salinity resistance. Differential biomass partitioning was observed among resistant and susceptible lines as well as within resistant lines, which were grown in large pots. Traits such as number of dead leaves and total number of nodes may be used as dominant markers for understanding the mechanism of resistance to salinity. Multi-location trials differing for salinity levels showed low and non-significant heritabilities across the environment for biochemical traits showing their sensitivity to the environment and a significant G X E interaction. Thus selection could only possible within the salinity level for these traits. Contrastingly, morphological traits such as number of nodes showed significant heritabilities (narrow or broad sense) across the environment. These traits may be exploited by the selection of inbred lines across or with salinity levels. Among various salinity levels, 12 dSm−1 was found to be feasible for screening and selection as it promoted the additive type of gene action.

Mentha arvensis L. (Ma) leaf extract, a wide source of natural antioxidants is widely used to protect animal cells against oxidative stress. In the current study, we have studied the ameliorative effects of Ma leaf extract on Mn induced oxidative stress in rice (Oryza sativa L.) seedlings. Hydroponically grown rice seedlings treated with 1.5 mM MnCl2 showed a decline in vigour and contents of photosynthetic pigments, increased production of reactive oxygen species (O2˙‾, H2O2, and.OH), lipid peroxidation, protein thiol and carbonyl contents along with increased activity of antioxidative enzymes- superoxide dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX). The activity of catalase (CAT), however, declined in the seedlings after prolonged Mn treatment of 8 days. Interestingly exogenous application of Ma leaf extract (638.4 mg ml-1) effectively restored the Mn-induced decline in seedling vigour, photosynthetic pigments, increased levels of H2O2, lipid peroxides and altered activities of antioxidative enzymes. The results indicate that exogenous application of Ma leaf extract significantly lowers the toxic effects of Mn in rice seedlings by modulating Mn translocation and reducing oxidative stress.

Twenty-eight genotypes including triticale, wheat and rye were grown in a greenhouse under control, 14 and 21 dS/m salinity (NaCl and CaCl2, 1:1 ratio) levels to assess variations in agronomic traits, and to assess association of dehydration responsive elements (DREB genes) and five microsatellite (SSR) markers with salt tolerance. The results of grain yield variation and principal component (PC) analysis for statistical indices revealed that the first PC under 14 and 21 dS/m salinity levels was associated with salt tolerance. Five microsatellite (Xgwm291, Xgwm312, Xgwm410, Xgwm2181 and Xgwm126) and two DREB (DREB1 and DREB2) markers were used for detection of polymorphism. In total, 35 alleles ranging from 130 to 850 bp in size were identified of which, 25 alleles were found for SSR markers and 10 belonged to DREB genes. The number of alleles ranged from 3 to 9 with an average of 5 per primer. The polymorphic information content (PIC) value ranged from 0.51 (Xgwm291) to 0.77 (DREB1) with an average of 0.68. The Xgwm291 primer amplified 3 bands (130, 160 and 185 bp) in triticale and wheat but neither were detected in rye. Remarkably, the 130 bp band was amplified in TRT826 which was categorized as salt tolerant on the basis of K+/Na+ ratio and grain yield variations. Accordingly, this band could be associated with salt tolerance and its isolation and sequencing could clarify its characteristics for possible use in marker assisted breeding (MAB) for salt tolerance in triticale and wheat.

Breeding using the double haploid approach has been used in accelerating the rice breeding process. However, the main obstacle in the application of this technique in rice is the low level of callus formation and their regeneration into haploid plants. Based on these issues, this research is aimed at developing the best method for obtaining double haploid plants through anther culture using three kinds of aromatic rice of Indonesian local varieties. Anthers of Pendok, Genjah Arum, and Merah Wangi varieties were cultured in callus induction media which were either supplemented with different types of carbon sources, or auxins and ethylene inhibitors. However, the application of different sugar types did not significantly affect callus formation of Pendok and Genjah Arum. However, auxin treatment showed NAA to be more efficient for the callus induction of Pendok, while 2,4-D had no effect on callus induction in all tested varieties. The addition of ethylene inhibitor successfully induced callus formation of Merah Wangi varieties, while the rates of Pendok and Genjah Arum were not significantly affected. Callus of three plant lines were then regenerated into plantlet in regeneration media. Of the three callus varieties used, only Pendok could regenerate into plantlets and grow into adult haploid plants.

Drought tolerance as such is often not considered to be an independent trait by plant breeders. The objective of this study was to evaluate eight drought tolerance indices, namely stress susceptibility index (SSI), yield stability index (YSI), yield reduction ratio (Yr), yield index (YI), tolerance index (TOL), mean productivity (MP), geometric mean productivity (GMP), and stress tolerance index (STI) in upland cotton (G. hirsutum L.) genotypes. For this purpose, 16 genotypes were sampled during the 2013-2014 growing seasons under both normal and drought-stress field conditions at the Main Cotton Research Station of Navsari Agricultural University, Surat, India. The drought tolerance indices were calculated based on seed cotton yield under drought stress and non-stress conditions. Mean comparison of drought tolerance indices and seed cotton yield validated the significant influences of drought stress on yield as well as significant differences among genotypes. Results of calculated correlation coefficients and multivariate analyses showed that GMP, MP and STI indices were able to discriminate drought-sensitive and tolerant genotypes. Cluster analysis using the drought-tolerance indices divided the 16 genotypes into tolerant and susceptible groups. Two genotypes, G.Cot.16 × H-1353/10 and H-1353/10 × G.Cot.16 gave good yield response under drought conditions leading to their stability during water stress conditions. Based on multivariate analyses using the indices individually or in combinations, it was possible to identify the most yield-stable genotypes across the environments. Overall, we concluded that GMP, MP and STI indices can be efficiently exploited not only for screening drought tolerance but also to identify superior genotypessuitable for both stress and non-stress field conditions.