K. Usha

Salicylic acid induced physiological and biochemical changes in wheat seedlings under water stress

Salicylic acid (SA) is an important signal molecule modulating plantresponses to stress. It is recently reported to induce multiple stresstolerancein plants including drought. An experiment was, therefore, conducted toascertain the effect of salicylic acid on the growth and metabolic profile ofwheat seedlings under water stress. Irrespective of the SA concentration(1–3 mM) and water stress, SA treated plants showed, ingeneral, a higher moisture content, dry mass, carboxylase activity of Rubisco,superoxide dismutase (SOD) activity and total chlorophyll compared to those ofuntreated seedlings. SA treatment, under water stress, protected nitratereductase (NR) activity and maintained, especially at 3 mM SAconcentration, the protein and nitrogen content of leaves compared to watersufficient seedlings. Results signify the role of SA in regulating the droughtresponse of plants and suggest that SA could be used as a potential growthregulator, for improving plant growth under water stress.

Nodulation and Symbiotic Nitrogen Fixation of Cowpea Genotypes as Affected by Fertilizer Nitrogen

Abstract Intercropping with legumes and non‐legumes is commonly practiced in many parts of the world to maximize productivity per unit area of land. In India, cowpea [Vigna unguiculate (L.) Walp] is a popular pulse legume component of intercropping farming systems. Often, however, potential production is compromised, particularly in high fertilizer input systems, because legume component competes with the non‐legume component of the system for nitrogen (N) in the soil. An experiment was conducted in order to identify lines of cowpea that could obtain the majority of their nitrogen requirements from symbiotic fixation of atmospheric nitrogen rather than from uptake of soil nitrogen. Twenty‐nine genotypes of cowpea were screened for tolerance to (applied) nitrogen in soil in field condition. The parameters used to appraise tolerance were extent of root nodulation, the amount of nitrogen fixed, nitrate reductase activity (NR) in roots and nodules, and nitrite content of roots and nodules. There were two nitrogen treatments applied as urea, 40 kg N per ha (N40), and 120 kg N per ha (N120). There were three genotypes whose nitrogen‐fixing effectiveness was apparently unimpaired by applications of nitrogen to the soil. Genotype EC‐170442‐3 nodulated and fixed atmospheric nitrogen satisfactorily at higher levels of applied nitrogen. At N40, genotypes EC‐244390 and EC‐240900 formed a great abundance of large nodules effective in nitrogen fixation; even at N120, EC‐240900 had better symbioses than the majority of the 29 cowpea lines originally screened. These three genotypes are deemed worthy of further examination for their suitability for intercropping systems. How this might be achieved is discussed.

Growth and Nutrient Uptake Responses of Kinnow to Vesicular Arbuscular Mycorrhizae

In a field experiment, three-year-old Kinnow trees budded on Jatti Katti (C. jambhiri) rootstock were inoculated by three different arbuscular mycorrhiza (AM), Glomus manihotis (T1), Glomus mosseae (T2), and Gigaspora gigantia (T3), separately or in combination (T4). Microscopic assessment of AM colonization on Kinnow roots showed a relatively lower level of infection by different species when inoculated separately than when inoculaed together. Application of AM improved growth parameters like plant height, canopy volume, mean leaf area, and number of new shoots per plant but had no effect on trunk diameter, number of leaf per new shoot and new shoot diameter. Flowering phenology was also altered by AM infection. The infected plants produced more flowers which despite abscission caused an increase in the initial number of fruits. AM inoculation increased plant phosphorous in T3, potassium in T1, T2, T3, calcium in T2, T3, T4, and the AM-nutrient relationship did not reveal any generalized pattern. Inoculated plants, however, had higher concentration of different elements by the second year of the experiment indicating towards the continuous and cumulative effect of AM infection on plant nutrient accumulation. Further, the beneficial effects of AM on Kinnow were not related to the difference in the species of mycorrhiza.

Effects of salt stress on growth, nodulation, and nitrogen and carbon fixation of ten genetically diverse lines of chickpea (Cicer arietinum L.)

Salinity is one of the major environmental constraints affecting agriculture in major regions of the world. It is known to depress greatly the growth and symbiotic performance of nodulated legumes. In the present study conducted over 2 rabi (dry) seasons, 2000–01 and 2001–02, 10 genetically diverse chickpea lines were compared for salt tolerance in terms of growth, nodulation, moisture content, and nodule nitrogen and carbon fixation. Chickpea lines were raised in an open-air chamber in soil supplied with 0, 50, 75, and 100 mm NaCl. The shoot, root, and the single-plant weight declined with increasing level of salt. Chickpea lines BG-1075 (desi type) and BGD-70 (Kabuli type) showed better plant growth than the former 2 lines but were poorer in nodulation under salt stress. An almost identical pattern of salt response was observed for nodule number, weight per nodule, nitrogen, and carbon fixation among the chickpea lines. No distinct relationship was found among root/shoot ratio, plant moisture content, and salt tolerance response of the chickpea. However, nodulation capacity (number and mass) under salt stress was related to salt tolerance response of chickpea lines. This trait could be used for improvement of salt tolerance of this legume species in order to increase its productivity and stability in saline soils.

Scanning electron microscopic studies on floral malformation in mango

Studies with scanning electron microscope in mango variety Amrapali revealed the presence of many hair line cracks, pin-sized to large holes, disorganised cells and fungal mycelial infection at the base of the malformed bud during bud-inception stages. Among other possible reasons, tissue damage caused by the fungi and sucking pests may lead to the abnormal development of the malformed tissues.

Relationship of molecular mobility of water with floral malformation in mango as assessed by nuclear magnetic resonance

Abstract Spin lattice relaxation time (T1) was measured for various healthy and malformed parts of mango by proton pulsed nuclear magnetic resonance (NMR) at 20 MHz and at room temperature. The T1 values were high in malformed parts compared with healthy parts, indicating that the molecular mobility of water is relatively higher in malformed parts. However, in stem parts near to malformed panicles (1–2 cm), T1 values were significantly higher compared with other parts. This indicates that the site of primary infection causing malformation is probably the meristematic region.

Microsatellite (SSR) marker assisted assessment of population structure and genetic diversity for morpho-physiological traits in guava ( Psidium guajava L.)

Twenty-four SSR markers were utilized to evaluate the genetic variation across thirty-six guava varieties including wild species. The SSR markers revealed a polymorphism of 95.7% and a great range of diversity among the experimental guava germplasm. Eighty-one alleles were detected, in diversity analysis, with 2–7 alleles with a mean of 3.682 alleles per loci. The SSR loci showcased an allele frequency of 0.306 (mPgCIR251) to 0.861 (mPgCIR227) at a mean value 0.561. An average polymorphic value of 0.490 across was measured for all the 36 germplasm with the range of 0.234 in mPgCIR227 to 0.706 in mPgCIR03. The genetic diversity for SSRs varied between 0.248 (mPgCIR227) and 0.747 (mPgCIR03) with an average of 0.548. Clustering of germplasm distinctly separated pink and white flesh germplasm into two major groups. First three coordinates contributed towards 32.76% of the variation measured using principle coordinate analysis. Molecular variance (AMOVA) study showed 06 and 94% genetic variation among population and individual, respectively with five sub populations. This study provides valuable information for understanding the genetic variability in guava which can be exploited to develop varieties with better fruit yield and nutritional quality.

Character association and path analysis studies in guava (Psidium guajava L.) for bioactive and antioxidant attributes

Character association and path analysis in fifty diverse indigenous genotypes of guava were studied during the year 2011 & 2012 for eleven major bioactive and antioxidant compound. The phenotypic and genotypic as-sociation of reducing and non reducing sugar was significantly positive with total sugar content, titrable acidity revealed positive and significant association with reducing sugar and ascorbic acid. Lycopene had positive and highly significant correlation with ascorbic acid, acidity and pectin. In path analysis pectin showed the highest positive direct effect (G 0.780, P 0.762) on total antioxidant followed by anthocyanin (G 0.16380, P 0.16438), lycopene (G 0.144, P 0.146), total soluble solid (G 0.136, P 0.138), non reducing sugar (G 0.129, P 0.078) and ascorbic acid (G-0.302, P-0.272), sugar: acid ratio (G 0.272, P-0.242), total sugar (G-0.196, P-0.120), acidity (G-0.020, P-0.013), and reducing sugar (G-0.017, P-0.043) showed negative direct effects on total antioxidant (μmol TE/100 g). Overall the path analysis confined that direct effect of pectin, anthocyanin, lycopene, TSS, non reducing sugar whereas indirect effect of ascorbic acid, sugar: acid ratio, total sugar, acidity, and reducing sugar should be considered simultaneously for amenability in bioactive and antioxidant compounds of guava.