Yield and Quality of Passion Fruit in Relation to Training Systems

Four different training systems, viz., Kniffin, High trellis, Tatura and Bower were evaluated in passion fruit cv. Kaveri. Kniffin system with 4 arms recorded highest cumulative yield of 67.22 t/ha with a cost:benefit ratio of 1:4.25, followed by Kniffin 2 arm and 6 arm, respectively. Kniffin system was also the most ideal system of training for passion fruit, facilitating easy cultural operations. Although Tatura system recorded highest cumulative yield/vine (43.57kg), it registered lowest yield/ha, largely due to lower plant population/ha (1250 vines/ha). Fruit quality parameters like TSS, Vit. C, carotene content and titrable acidity were not significantly influenced by different training systems. Similarly, interception of Photosynthetically Active Radiation (PAR) by the canopy did not differ significantly among training systems. Though photosynthetic rate did not differ significantly, shaded leaves in the canopy did not contribute photosynthates and were parasitic on the vine

Genome wide analysis of heat responsive microRNAs in banana during acquired thermo tolerance

MicroRNAs are a class of small regulatory RNAs in plants, which play vital roles during various abiotic and abiotic stress conditions including plant processes. In this present study, we examined the expression of miRNAs and their predicted target expression levels during heat stress in banana. Out of 235 miRNA found in Musa, 40 miRNA showed homology to heat responsive miRNAs from other plants. Further, 14 targets for miRNA were predicted that are potentially regulated by their cognate miRNAs and were monitored under three stages of stress viz, induction, induction + lethal alone using qPCR analysis. The results suggest that generally, there is a negative relationship in the expression patterns of miRNA and their predicted cognate targets - HSP70, HSP90, SAP, DNAj genes. These were highly up regulated and their respective miRNAs showed lower expression. This is the first report in banana, which demonstrated that during induction stress, various thermo-protective genes are activated at initial stages of stress to achieve thermotolerance through altered miRNA expression. The results will help in broadening our understanding acquired thermotolerance and their regulation by miRNAs in plants

Standardization of Spacing and Soil Volume Wetting for Drip Irrigationin Papaya (Carica papaya L.)

Field experiments in two crops of papaya were conducted at ICAR-Indian Institute of Horticultural Research for four years during 2016-19 to standardise spacing with optimum soil volume wetting for drip irrigation. Narrowing the plant rows drastically reduced the plant height while leaf production affected significantly due to reduction in intra row spacing. The height at first fruiting was significantly lower with a spacing of 1.8 m x 1.5 m (56.4 cm) significantly differing from both 1.5 m x 1.5 m (60.9 cm) or 1.8 m x 1.8 m (66.8 cm). Significantly higher mean fruit yield (42.2 t/ha) was recorded with the spacing of 1.5 m x 1.5m as compared to either 1.8m x 1.5m (23.4 t/ha) or 1.8m x 1.8m (22.1 t/ha). Significantly higher water use efficiency (71.3 kg/ha.mm) was recorded in papaya by following closer spacing of 1.5 m x 1.5 m. Among the interactions, higher papaya yield (48.0 t/ha) was recorded with normal drip irrigation (80% soil volume wetting) under closer spacing (1.5 m. x 1.5 m). Further, higher water use efficiency (129 kg/ha. mm) could be obtained by scheduling the irrigation at 30% soil volume wetting especially by planting at 1.5 m. x 1.5 m. spacing suggesting its suitability for water scarcity areas

Partial root zone drying irrigation in papaya (Carica papaya L.) for enhanced water use efficiency under limited water situations

Field experiments were conducted during 2015-17 at ICAR-Indian Institute of Horticultural Research, Hessaraghatta, Bengaluru, to standardize the partial root zone drying irrigation in papaya with 12 treatments in RBD design. The results indicated that better soil moisture in the root zone could be maintained under drip irrigation by shifting laterals on either side at fortnightly intervals as compared to fixed laterals with thesame amount of water. Significantly more primary roots (16.5/plant) were observed when irrigation was scheduled on one side with single emitter meeting 60% of the evaporative demand. PRD irrigation through shifting of laterals recorded significantly higher transpiration rate especially at 50% of ER (8.05 m mol m-2 s-1) as compared to the control (3.95m mol m-2 s-1). Further, the same treatment recorded significantly lower fruit cavity index (0.26) with relatively higher fruit volume (1388 cm3). Irrigating papaya only on one side with single emitter resulted in significantly higher T.S.S (13.0%). Higher water productivity (23.7 kg/m3) could be obtained by scheduling the irrigation at 40% evaporation replenishment through shifting of laterals with saving of substantial water (1285m3/ha) resulting in higher water use efficiency (237.4 kg/ha.mm)

Standardisation of soil volume wetting for drip irrigation in mango (Mangifera indica L.,)

Field experiments were conducted in mango for four years during 2017-2020 at ICAR-Indian Institute of Horticultural Research to standardise optimum soil volume wetting for drip irrigation. Wetting soil volume upto 70% recorded higher mean fruit yield of 34.8 kg/plant (9.68 t/ha)and with further increase in the level of soil volume wetting irrigation (upto 80%), there was a decline in the mango yield (7.40 t/ha). Similarly, significantly increased response was observed in fruit weight upto 70% soil volume irrigation (226 g) although there were no significant differences in the TSS of the fruit. Significantly higher water use efficiency was observed for 30% soil volume wetting irrigation (274.1 kg/m3) and further no significant differences were observed in water use efficiency between 50% and 70% soil volume wetting irrigations indicating that in areas of water scarcity, it is enough to scheduling the irrigation only upto 50% soil volume wetting in mango for economising the water (232.1 kg/m3)

Tomato late blight yield loss assessment and risk aversion with resistant hybrid

Late blight (Phytophthora infestans) is one of the devastating diseases of tomato worldwide. Field trial was carried out in Kharif 2019 and 2020 in Hesaraghatta, Bengaluru, Karnataka, India, to estimate yield loss due to late blight and to assess extent of protection in resistant genotype during late blight epiphytotics. Yield loss was calculated as per cent difference in yield between fungicides treated and unprotected plots in three F1 hybrids NS501, Arka Rakshak, both susceptible genotypes and Arka Abhed, a resistant genotype. Over two years, average yield loss due to late blight was 79.47 per cent in NS501, 75.53 per cent in Arka Rakshak and 12.84 per cent in Arka Abhed. With lower mean AUDPC values (147.22 in 2019 and 469.17 in 2020) and with low yield loss, Arka Abhed provided affordable protection against late blight. Our findings indicate late blight as an economically important peril to be considered for tomato yield loss coverage under insurance scheme in Bengaluru region. Arka Abhed hybrid can be cultivated to avert yield loss risk associated with late blight epiphytotics

Seed Germination and Seedling Growth in Solanum Species to Water Stress under in vitro Conditions

A study on seed germination and seedling growth was conducted with five cultivars of Solanum melongena L. (cvs. Arka Nidhi, B.P.L.H.-1, Arka Neelakanth, Arka Keshav and Mattu Gulla) and a wild species Solanum macrocarpon L. under different levels of osmotic potential induced by polyethylene glycol (PEG 8000). Germination declined progressively in response to decreasing (more negative) water potential, and no germination was found beyond - 0.4MPa in any of the cultivars/species. Except for cvs. Arka Nidhi, B.P.L.H.-1 and Mattu Gulla, no germination was seen at -0.4MPa Cultivar Arka Neelkanth failed to germinate under any of the osmotic concentrations tested. Response in term of root growth was better in Arka Neelkanth, followed by Arka Nidhi and B.P.L.H.-1, upto transfer from different levels of osmotic potential to Control (0MPa). Germination of primed seeds within 24h indicates that many processes leading to normal germination would have been completed during the priming process itself. In contrast to germination, growth extension in radicle was less sensitive to water stress

Genotypic Variability in Tomato for Total Carotenoids and Lycopene Content during Summer and Response to Post Harvest Temperature

Lycopene is the major carotenoid responsible for fruit colour in tomato (Lycopersicon esculentum Mill.). However, colour of the fruit is greatly affected by high temperature prevailing during fruit growth in the summer crop. To select a genotype suitable for summer conditions that can maintain colour better, a set of 52 tomato genotypes were evaluated for lycopene, total carotenoids and for TSS during summer in Bengaluru. Among the genotypes screened, IIHR 2892 recorded very high lycopene content (328.4mg/100g dry weight) and IIHR 2866 recorded very low lycopene content (25.2mg/100g dry weight). TSS values ranged from 2.6° Brix in cv. Vybhav to 7.0° Brix in IIHR 2866. In addition, study was carried out to determine the effect of postharvest temperature on biosynthesis of lycopene in five selected tomato cultivars (Arka Rakshak, Arka Samrat, Arka Ananya, Lakshmi and Abhinava). Tomatoes harvested at breaker stage were stored at 27° C, 35° C and 40° C for ripening. High temperature reduced lycopene content in tomato fruits. Lycopene synthesis in fruits was completely inhibited above 35°C. In this study, mean lycopene content in tomatoes stored at 27° C was 3-4 times higher than that in tomatoes stored at 40° C. This indicates that in tomatoes, temperature at which the fruits are stored after harvest, is a more important factor for colour development

Changes in Fruit Quality and Carotenoid Profile in Tomato (Solanum lycopersicon L.) Genotypes under Elevated Temperature

Tomato (Solanum lycopersicon L.) is a rich source of carotenoids, especially lycopene, and is affected severely by high temperatures under tropical conditions. To study the effect of elevated temperature on lycopene content and other quality parameters, five tomato genotypes, viz., RF4A, Abhinava, Arka Saurabh, IIHR 2195 and Arka Vikas, were grown in a temperature gradient tunnel (TGT) facility under 33.4 and 35.4°C temperature conditions. Fruits were analyzed for total carotenoids, total phenols, total flavonoids, total sugars, TSS, acidity, Vitamin C besides carotenoids profile (β-carotene, lycopene, phytoene and luteoxanthin content). Results revealed that all the quality parameters studied were superior at 33.4°C, compared to 35.4°C in all the genotypes. 'IIHR 2195' recorded highest total phenols (479.28mg/100g dw), total flavonoids (70.27mg/100g dw), ferric reducing antioxidant potential (FRAP) (310.53mg/100g dw), diphenyl picryl hydrazyl (DPPH) radical (487.89mg/100g dw), Vitamin C content (292.25mg/ 100g dw) and total sugars (606.88mg/g dw) at 33.4°C and at 35.4°C. 'RF4A' and 'Arka Vikas' were found to have better total carotenoids content and lycopene at higher temperature than other genotypes. 'Arka Vikas' recorded highest total soluble solids (TSS) (8.9°Brix) and acidity (0.80%) at 35.4°C. Higher TSS and acidity were recorded at 35.4°C than at 33.4°C in all the five genotypes. Genotypic variation was observed in the above stated biochemical parameters in response to elevated temperatures

Physio-biochemical responses of polyembryonic mango (Mangifera indica L.) genotypes to varying levels of salinity stress

Mango genotypes that are salinity tolerant can possibly be used as clonal rootstock for sustained production of salinity sensitive commercial mango cultivars in salt affected soils. Present study was carried out to elucidate the effect of salinity stress induced by salts of NaCl+CaCl2 (1:1) at concentrations of 0, 25, 50 and 100 mM on fifteen polyembryonic mango genotypes. The physio-biochemical parameters such as relative water content, chlorophyll content, epicuticular wax content, water potential (Ψ), carbohydrate content, lipid peroxidation, proline accumulation and antioxidant enzymes were determined at each level of salinity in all genotypes. On the basis of these physio-biochemical changes, the study illustrated that the polyembryonic genotypes, Turpentine, Deorakhio, Olour, Bappakkai, Vattam, Nekkare, Kurukkan, Kensington, Muvandan, EC-95862, Manipur, Sabre, Vellaikolamban, Kitchener and Mylepelian were in the decreasing order in response to salinity stress tolerance