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Research backgroundThere is considerable diversity in newly developed pummelo × sweet orange citrus hybrids. Most hybrids showed lower peel thickness and high juice yield but there is a lack of information on fruit quality parameters and molecular characterization. Therefore, the aim of the current study is to determine the content of antioxidants and properties of the fresh juice of 24 new pummelo × sweet orange citrus hybrids (Citrus maxima [Burm. f.] Osbeck × Citrus sinensis [L.] Osbeck) and the parental genotypes along with molecular characteristics determined using acidity specific markers. Experimental approach. The correlation and estimate of inheritance of the fruit juice properties: ascorbic acid, total phenol, total flavonoid, total antioxidant, total soluble solid and sugar contents, pH, titratable acidity, along with sensory evaluation was performed. Molecular characterization of these hybrids was carried out using de novo generated acidity specific simple sequence repeat (SSR) markers. Results and conclusions. The main constituents of the fruit juice of pummelo × sweet orange hybrids were observed in the range of w(ascorbic acid)=40.00–58.13 mg/100 g, total phenols expressed as gallic acid equivalents w(GAE)=40.67–107.33 mg/100 g, total antioxidants expressed as Trolox equivalents b(Trolox)=2.03–5.49 µmol/g, total flavonoids expressed as quercetin equivalents w(QE)=23.67–59.33 mg/100 g, along with other properties: total soluble solids=7.33–11.33 %, w(total sugar)=2.10–5.76 %, w(reducing sugar)=1.69–2.78 %, w(non-reducing sugar)=0.39–3.17 % and titratable acidity 1.00–2.11 %. The above parameters differed significantly in the fruit juice of the evaluated pummelo × sweet orange hybrids. Considering these parameters, the hybrids SCSH 17-9, SCSH 13-13, SCSH 11-15 and SCSH 3-15 had superior antioxidant properties in terms of these parameters. A higher heritability (≥80 %) was also observed for all juice properties. Molecular characterization of pummelo × sweet orange hybrids showed that >50 % of the hybrids were grouped with medium acidity parents. Both molecular and biochemical parameter-based clustering showed that interspecific hybrids exhibit transgressive segregation with increased antioxidants that help alleviate the health problems. Novelty and scientific contribution. These newly developed pummelo × sweet orange citrus hybrids are a valuable source of high-quality antioxidants for a healthy diet. The identification of trait markers that enable selection at the seedling stage is of great benefit to citrus breeders, as the characteristic features of a mature tree are not yet visible at the juvenile stage.

Citrus juice sac granulation reduces the yield of extractable juice and impairs its nutritional and functional quality. Therefore, present study was carried out to improve the physico-functional quality of juice extracted from partially granulated ‘Dancy’ tangerine. Juice was passed through microfluidizer under varying pressure (41, 62, 83, 103, 124 MPa) for different number of passes (1, 2, 3). The microfluidized juice was evaluated for different quality attributes, viz. cloud value, fractal dimension, lacunarity, colour attributes and pectin methyl esterase (PME) activity. Naringin and hesperidin were quantified through HPLC. Control juice exhibited the highest fractal dimension (18.89), indicating irregular cell structure, while 103MPa/3 passes (1.04) displayed the lowest indicating uniformity in juice. Microfluidized juice showed improved opalescence stability, greater hue, low PME activity and augmented hesperidin and naringin contents. Juice treated at 103 MPa for a single pass exhibited the best organoleptic quality. The high pressure applied during microfluidization can drastically improve the quality of otherwise low quality juice extracted from granulated citrus fruits. Application of appropriate processing pressure and number of passes through the microfluidizer yields citrus juice possessing enhanced bioactive constituents, reduced enzymatic activity with good organoleptic acceptability.

Heterozygosity is the major constraint in perennial fruit crop like mango for regular bearing breeding. Majority of the popular mango varieties have irregular bearing habit. Many external and internal factors affect the bearing habit of perennial fruit crops. Among internal factors, the level of carbohydrate reserves and phytohormones plays a major role on bearing habit of fruit crops like apple, citrus, mango, litchi etc., Therefore, present research work aimed to study the carbohydrate metabolism pathways in regular and irregular mango genotypes of varying origin. A total of 30 primers were designed using in silico mining of four key genes coding for citrate synthase, alcohol dehydrogenase, sucrose phosphate synthase and trehalose phosphate synthase. These genes play important role in sugar and starch metabolism in mango. Of these specific primers, 14 showed polymorphism among the genotypes studied. Gene diversity (GD), average number of alleles per locus (An), polymorphism information content (PIC) and major allele frequency (Maf) observed were 0.45, 2.14, 0.35, 0.59, respectively. Simple sequence repeats markers grouped 63.15% studied mango genotypes of regular bearers together. Further, these markers could be utilized in a greater number of genotypes for regularity.

The assessment of the optimum harvesting stage is a prerequisite to evaluating the performance of new citrus genotypes. The intrinsic and extrinsic fruit quality traits of citrus fruits change throughout their developmental process; therefore, to ensure the highest quality, the fruit must be harvested at an appropriate stage of maturity. The biochemical changes in terms of total soluble solids (TSS), titratable acidity (TA), TSS/TA ratio, BrimA (Brix minus acidity), and ascorbic acid, in addition to the organoleptic acceptability of 16 new interspecific citrus hybrids, were evaluated in New Delhi (India) during the H1-H8 harvesting stage at 15-day intervals to standardize the optimum harvesting stage. The TA and ascorbic acid content were at a maximum level during the early harvesting stage and declined with time, reaching the minimum level in the last harvesting stage. The TSS, TSS/TA ratio, and BrimA values were found to have an increasing trend up to the last stage in most of the hybrids. The juice content shows an inclining trend during the initial harvesting observations, followed by stable juice content and then a decline. The BrimA was found to be a better predictor for consumer acceptability compared to the traditional maturity index TSS/TA ratio and, thus, harvesting maturity. Specific TSS, TA, and BrimA values, in addition to the juice percentage and ascorbic acid content, corresponding to the highest hedonic score, were judged as the optimum harvesting stage indicators for an individual hybrid genotype. Among the interspecific hybrids, SCSH-9-10/12, SCSH-11-15/12, and SCSH-17-19/13 were found to be superior, having better juice acceptability organoleptic scores (≥6.0) and higher juice content (≥40%). Principal component analysis based on fruit physico-chemical traits could be able to distinguish the optimum maturity stage in all of the citrus genotypes.

Most of the popular scion varieties of mango possess alternate/irregular bearing. There are many external and internal factors assigned, among them carbohydrate reserves, and nutrient content plays important roles in the floral induction process in many crop species. In addition to that rootstock can alter the carbohydrate reserve and nutrient acquisition of scion varieties in fruit crops. The present investigation was carried out to understand the effect of rootstocks on the physiochemical traits of leaf, and bud and nutrient content in regular and alternate bearing varieties of mango. The rootstock "Kurukkan" promoted starch content in leaves of both alternate bearing varieties 'Dashehari' (5.62 mg/g) and regular 'Amrapali' (5.49 mg/g) and encouraged higher protein content (6.71 mg/g) and C/N ratio (37.94) in buds of alternate bearing 'Dashehari'. While Olour rootstock upregulated the reducing sugar in leaves of 'Amrapali' (43.56 mg/g) and promoted K (1.34%) and B (78.58 ppm) content in reproductive buds of 'Dashehari'. Stomatal density in 'Dashehari' scion variety was found higher on Olour rootstock (700.40/mm 2), while the rootstock fails to modify stomatal density in the scion variety regular bearer 'Amrapali'. Further, a total of 30 carbohydrate metabolism-specific primers were designed and validated in 15 scion/rootstock combinations. A total of 33 alleles were amplified among carbohydrate metabolism-specific markers, which varied from 2 to 3 alleles with a mean of 2.53 per locus. Maximum and minimum PIC value was found for NMSPS10, and NMTPS9 primers (0.58). Cluster analysis revealed that scion grafted on Kurukkan rootstock clustered together except 'Pusa Arunima' on Olour rootstock. Our analysis revealed that Fe is the key component that is commonly expressed in both leaf and bud. Although Stomatal density (SD) and Intercellular CO2 Concentration (Ci) are more specific to leaf and Fe, B, and total sugar (TS) are abundant in buds. Based on the results it can be inferred that the physiochemical and nutrient responses of mango scion varieties are manipulated by the rootstock, hence, the scion-rootstock combination can be an important consideration in mango for selecting suitable rootstock for alternate/irregular bearer varieties.

India is one of the leading citrus−producing countries, next to China and Brazil. Despite the sizeable production, especially of lemons and limes, India contributes meagerly to the world’s citrus market. Of the various factors responsible for the restricted quantum of citrus export, citrus canker (Xanthomonas citri pv. citri) is one of the leading serious causes and directly impacts the appearance of the fruits. Considering the extent of damage, the present study aimed to understand the impact of Xanthomonas citri pv. citri (Xcc) on the physio−biochemical responses in contrasting Citrus spp. Two genotypes, each of three citrus species, namely Citrus aurantifolia (Pusa Udit and ALC−35), C. limon (Kagzi Kalan and Konkan Seedless), and C. paradisi (Redblush and Marsh Seedless), were artificially inoculated with Xcc (108 to 109 cfu/ mL) by the pinprick method. The physio−biochemical changes in the host were evaluated after 48 h post inoculation (hpi). The chlorophyll content (total, a, and b) degradation and reduction in leaf gas exchange parameters, such as photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), and intrinsic water−use efficiency (iWUE), were measured to a greater extent in susceptible than resistant genotypes. The microscopic observations also evidenced higher stomatal density with larger stomatal areas in susceptible genotypes, favoring the easier penetration of Xcc in host tissues than resistant species or genotypes. The higher activities of various antioxidant enzymes, viz., superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione reductase (GR), the contents of soluble protein, and phenolics were measured in resistant genotypes in contrast to susceptible genotypes. The activities of phenyl ammonia lyase (PAL) and polyphenol oxidase (PPO) were also higher in resistant genotypes, whilst the levels of ROS (superoxide radical and hydrogen peroxide) production were enhanced in susceptible genotypes. Based on the host–pathogen interaction, the order of resistance in a descending manner was found as Kagzi Kalan, Marsh Seedless, Redblush, Konkan Seedless, Pusa Udit, and ALC−35. Further, the results will enhance the understanding of the pathogen mechanism during pathogenesis in resistant and susceptible Citrus species.

A new whitefly genus, Rudisculptus gen. nov. is described for its type species Rudisculptus caudalis gen. et sp. nov. feeding on Orophea katschallica Kurz (Annonaceae) from the Andaman Islands, India. Rudisculptus gen. nov. is similar to the New World genus, Aleuropleurocelus Drews & Sampson, 1956 and an Old World genus, Tetralicia Harrison, 1917 in pupal morphology, but differs in having the first abdominal setae, thoracic tracheal pores, caudal furrow, differentiated cephalothorax in slide mounts, the lingula excluded beyond the vasiform orifice. The new genus also differs from an Old World genus, Regiominutus Dubey, 2021 in habitus, pattern of wax secretion, shape, size, cuticle colour, raised lateral margin, extension of segment sutures and the lingula reaching outside the margin of the vasiform orifice, and in having the thoracic tracheal folds. Orophea katschallica is recorded as a new host plant for the whiteflies. Images of puparial habitus and types, line drawings and scanning electron microscope (SEM) microphotographs are provided.

To explore the quality rootstocks which impart better quality fruits in mango varieties, we studied the interactive effect of the scion and rootstock using five mango varieties (Mallika, Amrapali, Dashehari, Pusa Arunima, and Pusa Surya) grafted on three rootstocks (Olour, Kurukkan, and K-5). A total of 25 physico-chemical parameters were studied in the five grafted varieties viz., fruit weight, yield efficiency, fruit per plant, pulp percent, total soluble solids (TSS), acidity, physiological loss in weight (PLW), peel thickness, respiration rate, etc., and were found to be altered through scion–rootstock interaction. Among the five mango varieties, Olour rootstock proved best to improve the fruit quality and shelf life using the grafting approach. Physico-chemical-traits-based clustering was unable to precisely group scion varieties according to their grafting rootstock. A total of 35 shelf-life specific markers were designed from ripening genes, such as expansin, polygalactouranase, ethylene insensitive, ethylene sensitive, etc. Of these specific primers, 24 showed polymorphism among the studied genotypes. The gene diversity (GD), allele per locus (An), polymorphism information content (PIC), and major allele frequency (MAF) observed were 0.43, 2.00, 0.34, and 0.63, respectively. Cluster analysis clearly showed that scion grafted on Kurukkan and Olour rootstock, and scion varieties grafted on K-5 rootstock grouped together have more similarity. A total of eight simple sequence repeats loci (SSRs) markers were associated with eight physiological traits. Strong association of SSR loci NMSLC-12 and NMSLC-14 with yield efficiency and fruit weight were observed with a phenotypic variance of 85% and 70%, respectively.

Most tree fruits are commercially grown on different root systems, hence called composite plants. The section provides the root system as the rootstock, and the atop ground portion is called the scion. The combination is selected based on different traits of scion varieties, rootstock, and prevailing edaphic situations. The dated back plant propagation technique of joining two plants (grafting/budding) that directly communicates new physiological traits to the desirable scion variety from the rootstock remains unclear. In spite of this, this propagation technique continues widely applied in the multiplication of several fruit plant species. In a grafted plant, rootstocks impacted the scion variety’s growth, yield and quality attributes, physiology, nutrient accumulation as well as biotic and abiotic stress tolerance in many ways. Modern research in plant science for next-generation sequencing providing new vital information about the molecular interactions in composite plants multiplied using grafting. Now it was confirmed that genetic exchange is occurring between rootstock and scion variety through grafting joints. In this aspect, we discuss the process and the molecular mechanism of rootstock scion interactions. This review finally explains the dynamics of rootstock–scion interactions as well as their effect on physiology in terms of production, environmental stresses, and fruit quality. The morphological, physiochemical, and molecular mechanisms have been reviewed to develop an integrated understanding of this unknowable process that questions existing genetic paradigms. The present review summarizes the reported molecular mechanism between scion and rootstock and the impact of rootstocks on the production biology of scion varieties of economically important fruit crops and identifies numerous key points to consider when conducting rootstock scion interaction experiments. Rootstocks may offer a non-transgenic approach to rapidly respond to the changing environment and expand agricultural production of perennial fruit crops where grafting is possible in order to meet the global demand for fruit, food, and demands of the future.

The effect of pre-harvest application of Methyl Jasmonate (MeJA) on berry quality, flavonoid content and antioxidant capacity in grapes (Vitis vinifera L.) cv. Pusa Navrang were studied under subtropical conditions of New Delhi. Different doses of MeJA (0, 5, 10, 15 mM) were applied at three different dates. There were no significant differences were recorded for bunch and berry weight. Grapes treated with MeJA had slightly higher soluble solid content, lower titratable acids than untreated berries. Methyl jasmonate significantly enhanced the content of total monomeric anthocyanins, total phenolics, flavonoids and the antioxidant capacities in the berries. These were found significantly different for dose of methyl jasmonate and time of application. In general, when MeJA(10 mM) applied at veraison stage was found most effective for improving the berry bioactive compounds and had significantly higher total monomeric anthocyanin (1434.43 C3GE mg/kg fresh berry weight), total phenolic content (504.58 mg/100 g), total flavonoid content and antioxidant activity measured in terms of DPPH.

A tractor engine was fuelled with blends of dewaxed-degummed jatropha oil and diesel up to 50:50 (v/v) ratio. Higher power was obtained with treated oil than raw oil for all fuel blends. The engine operated well up to the blend ratio of 30:70 with treated oil and then there was sudden drop in engine speed under overload conditions. It was also found that there was sharp power drop with treated oil for the blends above 20 per cent, and hence the blend ratio of 20:80 (treated jatropha oil: diesel) was optimized for long duration operation. Power increase of 11.8 per cent with treated oil over raw oil was obtained at rated speed with optimized blend ratio, in spite of 5.5 per cent power drop with treated oil over diesel due to lower calorific value of plant oil. There was 2.8 per cent increase in torque with treated oil than raw oil. Brake thermal efficiency reduced with the percentage of plant oil in the blend and there was 2.5 per cent reduction with treated oil over diesel. A saving of 4.3 per cent in specific fuel consumption was achieved by using treated oil over raw oil. While CO, CO2, and HC decreased with blend ratio up to 25 per cent and then increased, NO and NO2 increased with blend ratio. The SO2 reduced with the increase in blend ratio due to the fact that plant oil contains no sulphur. There was no significant difference in smoke density between operation of engine with diesel and 20:80 blend at rated engine speed. Noise level and mechanical vibration had declining trend with the treated oil up to 25 per cent blend. There was no adverse effect with the operation of tractor engine up to 200 h during long-run evaluation with optimized blend (20:80). Operation of tractor with treated jatropha oil is encouraging in spite of slight hike (7.3%) in cost of operation with respect to decrease in CO, CO2, HC, and SO2. The study revealed that treated jatropha oil has promising potential as a fuel substitute up to 20 per cent blending in diesel.