Correlation of Leaf Parameters with Incidence of Papaya Ring Spot Virus in Cultivated Papaya and its Wild Relatives

Papaya ring spot virus (PRSV) disease has been the major impediment in papaya cultivation. The disease is transmitted through three aphid vectors and field tolerance towards this disease varies among Carica papaya cultivars as well as within the Vasconcellea genus. Leaf morphological traits are known to have influence on the probing preferences of aphids. Hence, this study was conducted to know whether the leaf parameters could contribute to the incidence of PRSV possibly by influencing the probing or feeding behaviour of aphid vectors. Leaf parameters viz., leaf thickness, leaf epicuticular wax content, presence and type of trichomes, trichome density were correlated with disease incidence at field conditions. The result revealed that leaf thickness along with epicuticular wax content had significant negative correlation with disease incidence. Similarly, trichome density had negative impact on disease incidence at 99.92% significance level. High epicuticular wax content and high trichome density in V. cauliflora and V. cundinamarcensis were found to be negatively associated with low to very low infection indicating that these parameters may have limited the vector transmission significantly

Screening of in vitro derived mutants of banana against nematodes

Investigations were carried out to screen the in vitro derived mutants of banana cv. Robusta (Caveidish- AAA) and Rasthali (Silk- AAB) by using certain bio-chemical parameters including some enzyme activities. The mutants tested were Ro Im V4 6-1-1, Ro Im V4 6-1-2, Ro Im V4 6-2-1, Si Im V4 10-5-3, Si Im V4 4 6-2-5 along with respective susceptible checks (Robusta and Rasthali), tolerant check (Anaikomban- AA) and resistant check (Pisang Lilin- AA). Various biochemical assays used were total phenol, tannin content, lignin content, peroxidase, polyphenol oxidase, phenyl alanine ammonia lyase and ascorbic acid oxidase. The results revealed that the mutants namely Ro Im V4 6-1-1 and Si Im V4 10-5-3 were found to be resistant while the mutant Ro Im V4 6-2-1 was moderately resistant. The rest of the mutants namely Ro Im V4 6-1-2 and Si Im V4 6-2-5 were found to be susceptible to nematodes. The resistant and moderately resistant mutants of banana could be further used in breeding programmes as well as being recognized as potential cultivars of commerce.Key words: Banana, nematode, resistance, biochemical parameters, enzymes, screening

Effect of Foliar Spray of Nitrogenous Chemicals on Flowering, Fruit Set and Yield in Mango (Mangifera indica L.) Cv. Alphonso

Effect of foliar application of various nitrogenous chemicals on flowering, fruit set and yield of mango cv. Alphonso was studied at the orchard of Horticultural College and Research Institute, Coimbatore, during 2010 - 2011. Maximum number of flowering shoots (68.7%), number of panicles (7.5/m2), panicle length (31.4cm), number of hermaphrodite flowers (282.5/panicle), fruit set (17.0%), number of fruits (146.0/tree) and fruit yield (43.8 kg/tree) was obtained with foliar spray of KNO3 at 2% concentration. Higher content of chlorophyll (1.7g mg-1), carbohydrate (14.5g 100g-1) and nitrogen (1.43%) and higher C/N ratio (10.18) were also recorded in plants sprayed with 2% KNO3, followed by 1% KNO3

Molecular Diversity Analysis in F3 Intergeneric Population of Papaya (Carica papaya L.)

Attempts were made to estimate molecular diversity present in F3 populations of intergeneric crosses between Carica papaya L. (Var. Pusa Nanha and CP 50) and Vasconcellea cauliflora. Molecular studies revealed that PCR amplification using five ISSR primers in 40 F3 progenies yielded 53 reproducible amplified bands. Of the 53 bands, 44 were polymorphic (83.02%). Polymorphic Information Content (PIC) value ranged between 0.90 (ISSR 807 x 810) and 0.66 (ISSR 834 x 810). Similarity coefficients based on five ISSR markers ranged from 0.05 to 0.96. Maximum similarity was observed for genotypes 1, 4 and 6 of Pusa Nanha x Vasconcellea cauliflora (0.96). Minimum similarity was observed between genotypes 3 and 14 of CP 50 x Vasconcellea cauliflora (0.04). This higher genetic diversity of papaya progenies stands to contribute to development of new varieties and, using the data, further hybridization and selection can be planned

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Not AvailableThe objective of the present study was to investigate the influence of hexanal formulation on delaying ripening as well as its impact on quality attributes of mango cultivars Banganapalli and Alphosno. th th Treatments included 2% hexanal formulation pre-harvest spray at 15 and 30 day before harvest, post-harvest dip for two minutes, combination of spray and dip and no spray and dip stored at ambient and cold storage condition. The physiological parameters revealed loss in weight, respiration rate, ethylene evolution rate and fruit firmness of fruits subjected to combination of pre-harvest spray and post-harvest dip with hexanal formulation and kept in cold storage were superior as compared to control under ambient storage condition. Treatments with hexanal formulation significantly influenced total sugars, total carotenoids and total flavonoids in the fruits. Ascorbic acid content and total antioxidant activity was enhanced in pre- and postharvest hexanal formulation treatments as compared to control by 11% and 28%. The effect of hexanal formulation as pre-harvest spray and post-harvest dip extended the shelf life of mango fruits from 5 days to 10 days in ambient storage and from 12 days to 20 days in cold storage. Pre and post-harvest hexanal formulation treatments along with cold storage offers significant promise to increase the post-harvest fruit quality and reduce post-harvest losses in mango

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Impact on Physiological Parameters upon PRSV Infection in Different Genotypes of Carica papaya L. and Vasconcellea species

Not AvailablePapaya is major tropical fruit gaining importance throughout the tropics and subtropics but there is a severe restriction in its production due to the serious disease known as Papaya Ring Spot Virus (PRSV-P).No papaya variety till date was identified as having durable resistance to PRSV-P; whereas several species of Vasconcellea, a close relative of papayawas reported to have heritable resistance to Papaya Ring Spot Virus. To understand these changes in physiological parameters upon PRSVinfection this study was carried out by involving six Caricapapayavarieties, two intergeneric hybrids of Carica papayaand Vasconcellea caulifloraand three Vasconcelleaspecies. The physiological parameters viz., photosynthetic rate (PN), stomatal conductance (gs) and transpiration rate (E) were measured before inoculation, and subsequently 7 days post inoculation (7 dpi) with PRSV, 14 dpi and 30 dpi. The results revealed that the photosynthetic rate and stomatal conductance were found get reduced in the susceptible genotypes viz., Arka Surya, Arka Prabhath, Red Lady and Pusa Dwarf at all the stages of observation, while in tolerant genotypes such as Pusa Nanha, TNAU papaya CO8, they initially decreased at 7 dpi but found to be raised at 14 dpi but again declined during the observation on 30 dpi. In IGH1 and IGH2, PN and gs were found to be increased at 7 dpi but decreased afterwards. In susceptible genotypes, transpiration rate was found to be increased continuously upto 14 dpi and reduced at 30 dpi. The physiological parameters did not show any significant alterations in the photosynthetic rate, stomatal conductance and transpiration rate in the three Vasconcellea species evaluated

Cost Benefit Analysis of Drip Fertigation and Flower Induction in Pineapple (Ananas comosus (L.) Merr.) variety ‘Giant Kew’ in Goa, India.

Not AvailableThe economics of drip fertigation and flower induction in pineapple variety ‘Giant Kew’ in Goa state, India was estimated in the present study. The field experiment was conducted in split plot design with six main plot treatments viz., F0- Surface irrigation + Conventional application of 100 % RDN (12:4:12 g NPK/ plant/ cycle), F1-Drip irrigation + Conventional application of 100% RDN (12:4:12 g NPK/ plant/ cycle), F2- Fertigation with 125% RDN (15: 5:15 g NPK/ plant/ cycle), F3- Fertigation with 100 % RDN (12:4:12 g NPK/ plant/ cycle), F4-Fertigation with 75 % RDN (9:3:9 g NPK/ plant/ cycle) and F5- Fertigation with 50 % RDN (6:2:6 g NPK/ plant/ cycle) and two flower induction treatments (T1:Ethephon 25 ppm+ Urea (2%) + Sodium Carbonate (0.04%), T2: NAA 25 ppm) along with a control (T0) as the sub plot treatments. The establishment cost of drip was calculated and a depreciation of 4 %, 10 % interest on cost and 2 % repair and maintenance cost were considered for the calculation of the fixed costs and operating costs. The total cost of cultivation was estimated by adding the fixed costs and operating costs along with the main plot and subplot treatment costs. The highest total cost of cultivation of ₹ 421295.05 was recorded in F2T2 followed by F2T1 (₹420860.04). The net returns were calculated by deducting the total cost of cultivation from the gross returns. Among all the treatments, the net returns were the highest in F2T1 (₹1383500.47) followed by F3T1 (₹1396412.28).The highest B: C ratio of 3.34 was obtained in F3T1 followed by F2T1 (3.32). Fertigation with 100 % or 75 % RDN by straight fertilizers and flower induction by Ethephon 25ppm+ Urea (2%) + Sodium carbonate (0.04%) can give maximum returns in ‘Giant Kew’ pineapple production in Goa.Not Availabl

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Not AvailableThe present investigations were undertaken to evaluate the F2 intergeneric population of Carica papaya (var. Pusa Nanha, CP 50 and CO 7) and Vasconcellea cauliflora for PRSV resistance. Investigations were also made to estimate the mean performance, genetic parameters governing different traits and reaction to the PRSV in the F2 population. Among the crosses, Pusa Nanha × V. cauliflora recorded superior mean performance for fruit yield, number of fruits per tree and fruit biochemical parameters than other two crosses in F2 generation. Mean performance for papain recovery per fruit and the enzyme activity were high in CP 50 × V. cauliflora. Fruit quality parameters were high in CO 7 × V. cauliflora. Desirable mean performance for days taken for disease after inoculation and disease intensity score were recorded by Pusa Nanha × V. cauliflora. Among the various characters studied, higher GCV, PCV, heritability and genetic advance as percent of mean were registered by the cross Pusa Nanha × V. cauliflora for all the morphological characters and fruit yield parameters. From the F2 population 24 plus trees were selected for further evaluation based on their performance viz., morphological, yield, quality and biochemical characters and reaction to PRSV.Not Availabl