Healthy Panicles Research Articles

Multiple-Criteria Decision Analysis for Effect of Shoot Growth at Difference Combination Nutrient Fertiliser NPK for Harumanis Mango

It is vital to have the correct fertiliser arrangement for effective tree development, fruit yield, and essential fruit quality. The amount of fertiliser suggested with adequate nutrition will be maintained in the soil to supply the needs of the trees as they grow throughout the various growth stages. This study evaluated the effect of different combinations of Nitrogen(N), Phosphorus(P), and Potassium(K) on the vegetative flush physiology of Harumanis mango (Mangifera Indica. L). Single and combinations of N (511g), P(511g), and K(255g) fertilisers were used, which were N, P, NP, and NPK throughout May 2021. The results revealed that the minimum number of mature green leaves and a higher number of healthy panicles were observed in the NPK-treated plants. Moreover, NPK treatment showed the lowest malformation intensity percentage compared to other fertiliser treatments. The data were analysed to obtain the best regrowth pattern of shoots using Multiple-Criteria Decision Analysis (MCDA) techniques. The results on the pattern of regrowth after pruning when federalised with NPK fertiliser showed that the maximum percentage of total vegetative flush was 87.5% and the remaining 12.5% did not reach a satisfactory level according to the MCDA analysis.

Yield loss assessment in rice (Oryza sativa) due to false smut infection

Rice false smut caused by Ustilaginoidea virens is a destructive inflorescence disease threatening rice production worldwide. The disease is emerging in many rice growing countries including India. Estimation of yield loss helps to understand the importance of the disease and hence appropriate measures for its management may be devised. Therefore, an investigation was conducted in farmers' field of Odisha during kharif 2017. The disease incidence, chaffiness and yield loss for 20 rice genotypes were assessed following a standard method. Disease severity was calculated based on the number of smut ball in an infected panicle. False smut incidence varied from 6-33% while the disease severity ranged from 0.33-17.25% in different genotypes. The highest disease incidence was observed in Pooja (33.33%) followed by Varsha Dhan (16.67%) and Sarala (13.89%). The highest disease severity was observed in Pooja (17.25%) followed by Utkal Prava (10.46%) and Moti (8.89%). The healthy panicles have relatively higher weight and number of grain than the smut panicles. The smut panicle contained more number of chaffy grains than the healthy panicle. The yield loss of rice due to false smut infection varied between 0.10-5.14% in different genotypes. Maximum yield loss occurred in Moti (5.14%) followed by Gayatri (4.60%). The finding is significant as it indicates the emergence of false smut as a threat to rice production.

DECREASE IN PRODUCTION AND QUALITY OF GRAIN DUE TO NECK BLAST DISEASE IN SOME LOWLAND RICE VARIETIES

Decrease in production and quality of grain due to neck blast disease in some lowland rice varieties. Neck blast disease of rice causes a decrease in yields both in quantity and quality. The study was conducted to see the effect of neck blast disease on the characteristics of grain and yields of several high yielding varieties of lowland rice. The varieties used were Ciherang, Inpari 4, Inpari 7, Inpari 8, and Inpari 9. The parameters observed were the incidence and severity of neck blast disease, the ratio of the size of the seeds of healthy and sick panicles and the estimated production. The analysis showed that all varieties planted were infected by neck blast disease, but based on Disease Incident rate in the Necks, Ciherang and Inpari 8 varieties reacted susceptible to neck blast disease, Inpari 7 and 9 were moderate and Inpari 4 was resistant to neck blast disease. The quality of panicle grain infected by neck blast disease has decreased the size of grain width and was significantly different from grain of healthy panicles in all varieties. The highest estimated productivity was Inpari 4 variety of 10,378 kg/ha which experienced a decrease in production by 35.86% and the lowest was Ciherang variety of 8,367 kg/ha which experienced a decrease in production by 48.37% when they were infected by neck blast disease.

Spread and yield loss mechanisms of rice stripe disease in rice paddies

Rice stripe disease is an economically important disease of rice caused by the Rice stripe virus (RSV), which is transferred by the small brown planthopper (SBPH). The recent rapid increase in damage to rice crops throughout Japan caused by this disease makes it imperative to develop control methods as soon as possible. To obtain basic data for developing such methods, we studied how the disease causes damage and spreads within paddy fields. Our investigations revealed that diseased plants first appear in mid-June to early July, after which the disease spreads from affected plants to adjacent plants. This suggests that SBPH carrying RSV enter paddy fields, where they infect plants as they move about and lay eggs. Subsequently, hatched viruliferous nymphs infect surrounding plants, thereby spreading the disease. Our analysis of the damage caused by rice stripe disease showed that the earlier the onset of disease, the more extensive the damage caused, and that the disease reduces yield by reducing the number of healthy panicles. This suggests that to reduce damage caused by this disease, it is necessary to ensure the growth of a sufficient number of healthy panicles by controlling the vector insect during the crop’s early growth period. To be most effective, pest control efforts should be timed to target either the first-generation adults that colonize the paddy fields or the second-generation nymphs and adults that cause the rapid increase in the number of diseased plants within a field.

The Importance of Optimum Tillering in Rice-An overview

Rice is the most widely consumed staple food for more than half the world's human population. It is a monocot plant, normally grown as an annual crop. In tropical regions, it can survive as a perennial and in many traditional rice habitats of Asia and Africa this property is exploited by the native farmers. The plant can perennate through ratoon production. Some cultivars produce ratoon crop for several years. Rice can be grown in different environmental conditions, but wetland cultivation is the most widely used method for rice production. Rice is actually the edible fruit, called as a grain or caryopsis. Rice germinates as a single culmed seedling, but soon after the seedling stage it produces primary, secondary and tertiary tillers which come forth at different stages of growth. Tillering potential of rice, an important aspect in rice cultivation, is genetically controlled. Tillers from the rice plant emerge in a specific chronological sequence and it mainly depends on its duration and morphology. Optimum tillering is very much important to develop primary and secondary tillers, all bearing healthy panicles. This concept is recent and it displaces the early concept of high tillering rice varieties.

First Report of Neofusicoccum parvum Causing Panicle Blight and Leaf Spot on Vitis heyneana in China.

The climbing vine, Vitis heyneana Roem. & Schult, is a member of the grape family endemic to Asia. Its fruits are used in wine production, and its roots, stems, and leaves can be used in medicinal materials. This plant is grown in Southwest China, as well as in India, Bhutan, and Nepal. Mulao Autonomous County in Guangxi Province is the only artificial cultivation area in China. During the summer of 2013, a panicle blight and leaf spot were detected on V. heyneana on four farms in Mulao Autonomous County. The symptoms were observed from the onset of florescence through fruit harvest. Brown lesions initially appeared at the base of a panicle and then extended to the whole panicle, finally causing the panicle to die and fruit to drop. When the disease developed on leaves, the symptom initially appeared as small dark brown circular spots, later enlarging into irregular spots (average diameter 6 mm) with a light brown center and dark brown rim. With severe disease, some individual leaves were affected by numerous spots, leading to premature senescence. Small sections of diseased tissue excised from 10 panicle and 10 leaf samples were plated on potato dextrose agar (PDA) and incubated at 28°C. Fungal colonies developed, initially with abundant white aerial mycelium, which turned olivaceous gray after 5 days and formed black pycnidia after 25 days. The conidia were hyaline, ellipsoidal to fusiform, externally smooth, thin-walled, and nonseptate. Thirty conidia were measured; the dimensions were 12.0 to 17.5 × 4.0 to 6.0 μm. Morphological characteristics of the isolates were similar to the descriptions of Neofusicoccum parvum (3). The isolate MPT-1 was selected as a representative for molecular identification. Genomic DNA was extracted and used for PCR to amplify the internal transcribed spacer (ITS) region and partial translation elongation factor 1-alpha (EF1-α) gene, using primers ITS1/ITS4 and EF1-728F/EF1-986R, respectively. The obtained ITS sequence (GenBank Accession No. KJ599627) and EF1-α sequence (KM921768) showed >99% homology with several GenBank sequences of N. parvum. Morphological and molecular results confirmed the isolate as N. parvum. For pathogenicity tests, detached, young healthy panicles and leaves of V. heyneana were surface-sterilized, wounded by sterile needle, and inoculated with mycelial plugs (3 mm in diameter) of four N. parvum isolates. Ten panicles and 10 leaves were used for every isolate. Control panicles and leaves were treated with sterile PDA plugs. All the samples were placed in a humid chamber (RH 90%, 28°C, 12 h of light) for 3 days. Symptoms similar to those observed in the field developed on all panicles and leaves inoculated with N. parvum isolates. N. parvum was reisolated from all inoculated, symptomatic tissues. The controls remained symptomless. N. parvum has been reported to cause trunk canker on V. vinifera (2), dieback on Cupressus funebris (3), and a leaf spot on Myristica fragrans (1). To our knowledge, this is the first report of N. parvum causing panicle blight and leaf spot on V. heyneana in China. Panicle blight caused a large number of fruits to drop and reduced the yield seriously. Some effective measures should be taken to control this disease.

Influence of soil moisture on growth and nutrient content in healthy and malformed panicles of mango varieties

A field experiment was conducted to study the effect of soil moisture on growth, nutrient status of healthy and malformed panicles of mango varieties. A total of 24 treatment combinations of irrigation and variety were tested in factorial randomized block design with three replications. The results of study revealed that an increase in soil moisture content delayed the bud initiation and panicle emergence. The minimum intensity (2.7 m2) and severity (24.7%) of malformation was recorded under restricted soil moisture conditions. The higher moisture content in soil increased the intensity (4.5 m2) and severity (42.7%) of malformation. The higher soil moisture level enlarged the panicles in terms of length (29.5 and 8.6 cm), fresh (37.3 and 70.6 g) and dry weight (21.4 and 28.2 g) of healthy and malformed types, respectively. Higher soil moisture enhanced the foliar contents of N, P, K and Zn in the leaves of healthy panicles and bearing shoots and higher contents of Fe, Mn and Cu in leaves of malformed panicles. Among the varieties minimum malformation intensity (2.9m−2) and severity (25.7%) of was recorded in Langra followed by Amrapali and Sunderja under Jabalpur conditions.

Outbreaks of Smut Caused by Tilletia maclaganii on Switchgrass in New York and Pennsylvania.

Switchgrass (Panicum virgatum L.) is a native perennial grass with potential as a biofuel crop. The smut fungus, Tilletia maclaganii (Berk.) Clint., is associated with significant biomass reduction in switchgrass in the Midwest (4), but has not been reported in the northeast United States in more than 60 years (New York in 1890 and Pennsylvania in 1946) (2,3). From 2007 to 2010, smutted panicles were observed on the majority of plants in stands of several switchgrass cultivars at the USDA-NRCS Plant Materials Center in Big Flats (Chemung County), NY; in production fields of several switchgrass cultivars near Meadville (Crawford County), PA; and in an ornamental bed of switchgrass in Ithaca (Tompkins County), NY. Smutted panicles emerged 3 to 4 weeks prior to healthy panicles, had a compact, club-shaped appearance, and enlarged florets with swollen ovaries that readily released a powdery mass of odorless, rusty orange-to-dark brown teliospores when pinched. The entire caryopsis of every floret within a panicle was smutted and the infected plants appeared stunted, indicative of systemic infection. The fungus from each location was identified as T. maclaganii based on host, habit, and teliospore morphology (3). Teliospores were pale yellowish brown to reddish brown, varied from globose to slightly irregular in shape, and averaged 21 μm (18 to 25 μm) in diameter. The exospore was thick (2 to 3 μm), finely verrucose, and no sheath was present. True sterile cells, pale yellow and 10 to 18 μm in diameter, were sparsely present. Teliospores germinated and formed large (40 to 60 × 3 to 6 μm), nonconjugating basidiospores within 20 h on 2% water agar (WA). Occasionally, we also found the floret-infecting species T. pulcherrima (1) on switchgrass at very low incidence in Big Flats, NY, but it was easily distinguished from T. maclaganii. Stratified seeds (3 g) of 'Shelter', washed and found to be free of teliospores, were dusted with 0.04 g of teliospores of T. maclaganii isolate Tm001NY09 (Cornell Plant Pathology Herbarium Accession CUP-67931) harvested from infected 'Shelter' in Big Flats, NY in 2009. Inoculated and noninoculated seeds were sown in seedling trays, transplanted, and evaluated at panicle emergence. There were no symptoms on plants from noninoculated seeds. Symptoms on inoculated plants were consistent with field observations and teliospores were reisolated from infected panicles and cultured on 2% WA. Teliospores harvested from a single panicle infected with Tm001NY09 were used for culturing and DNA extraction. The fully annotated sequence of the rDNA internal transcribed spacer and 5.8S regions of this isolate were deposited in GenBank (Accession No. JF745116). Smut outbreaks in New York and Pennsylvania suggest that T. maclaganii must be managed effectively if switchgrass production is to be sustainable in the Northeast.

Management of ufra disease of rice caused by Ditylenchus angustus with nematicides and resistance

The effects of nematicide application timing and type on the management of ufra disease of rice caused by Ditylenchus angustus were investigated in the rain-fed and irrigated rice ecosystems. A broad range of rice (Oryza sativa L.) genotypes were also screened for resistance to D. angustus. Ufra infestation was significantly reduced when 1 kg ai/ha furadan 5G was applied up to 20 d before transplanting of infested seedlings in the field. Three granular nematicides, sunfuran 5G, edfuran 5G and forwafuran 5G, all applied at 1 kg ai/ha were evaluated against ufra in comparison with 1 kg ai/ha furadan 5G and a non-treated control. In both the ecosystems, all the 3 nematicides significantly reduced the number of damaged-tillers and total ufra infestation compared to the non-treated control. Similarly, sunfuran 5G, edfuran 5G, and forwafuran 5G treated plots had 45.3 to 52.7% healthy panicles with 3.89 to 4.02 t/ha yield in rain-fed rice and 47.6 to 53.0% healthy panicles with 3.85 to 3.97 t/ha yield in rain-fed and irrigated rice, respectively. These yields were similar to furadan-treated rice in 2 ecosystems. Yield losses due to ufra disease were 49.1 and 42.4% in the rain-fed and irrigated rice, respectively. Soil application of the nematicides, forwafuran, edfuran and sunfuran was cost-effective especially in fields of endemic areas. A total of 53 rice entries were tested, only 4 entries, fukuhonami, hyakikari, akiyu taka and matsuhonami showed highly resistance reactions to D. angustus. Key words: Cost-effective, Ditylenchus angustus, management, nematicides, rice ufra disease, resistance reaction.

Discrimination of rice panicles by hyperspectral reflectance data based on principal component analysis and support vector classification.

Detection of crop health conditions plays an important role in making control strategies of crop disease and insect damage and gaining high-quality production at late growth stages. In this study, hyperspectral reflectance of rice panicles was measured at the visible and near-infrared regions. The panicles were divided into three groups according to health conditions: healthy panicles, empty panicles caused by Nilaparvata lugens Stål, and panicles infected with Ustilaginoidea virens. Low order derivative spectra, namely, the first and second orders, were obtained using different techniques. Principal component analysis (PCA) was performed to obtain the principal component spectra (PCS) of the foregoing derivative and raw spectra to reduce the reflectance spectral dimension. Support vector classification (SVC) was employed to discriminate the healthy, empty, and infected panicles, with the front three PCS as the independent variables. The overall accuracy and kappa coefficient were used to assess the classification accuracy of SVC. The overall accuracies of SVC with PCS derived from the raw, first, and second reflectance spectra for the testing dataset were 96.55%, 99.14%, and 96.55%, and the kappa coefficients were 94.81%, 98.71%, and 94.82%, respectively. Our results demonstrated that it is feasible to use visible and near-infrared spectroscopy to discriminate health conditions of rice panicles.

FRUIT SET SUCCESS OF THREE MANGO (MANGIFERA INDICA L.) CULTIVARS USING RECIPROCAL CROSSES

'Tommy Atkins' has general characteristics of tall trees, fruit with red blush skin and fair taste. It has reasonable anthracnose resistance, but is highly susceptible to mango malformation. Indian cultivars Amrapali and Mallika are small trees with sweet fruits, but their yellow skin color has low market acceptance. Due to their good characteristics for mango breeding, these cultivars have been used in hybridization studies, but their general combining ability - GCA for fruit set is still unknown. To support future crosses, an experiment was carried out at Embrapa Cerrados, in Brasilia, to study fruit set success or compatibility among these three cultivars. A completely randomized design with six treatments or crosses ('Mallika' x 'Tommy Atkins'; 'Tommy Atkins' 'Mallika'; 'Mallika' x 'Amrapali'; 'Amrapali' x 'Mallika'; 'Tommy Atkins' x 'Amrapali'; 'Amrapali' x 'Tommy Atkins') and five replications (panicles) were used. Opened flowers were discarded from healthy panicles, which were protected by perforated polyethylene bags. In the morning, young and still closed buds were removed, opened flowers were selected, emasculated and hand pollinated using anther of male progenitor. The panicles were bagged and tagged. Fruit set was studied weekly for six weeks. 'Mallika' had the lowest compatibility rate and 'Amrapali' x 'Tommy Atkins' had the best fruit set with 16.1% success.

Transmission of Claviceps africana Spores from Diseased to Non-Infected Sorghum by Corn Earworm Moths, Helicoverpa zea

ABSTRACT The potential of corn earworm moths Helicoverpa zea, an important pest of sorghum in Texas, as a passive vector of sorghum ergot, Claviceps africana was assessed. Laboratory-reared (females and males) and field-moths trapped in sex pheromone traps were confined in screen cages with potted male-sterile sorghum line AT×623 that had been artificially infected with sorghum ergot and was producing massive amounts of honeydew that contained spores of the fungus. In the cages, moths were observed feeding on the honeydew. When laboratory-reared moths contaminated with C. africana spores were released for 12 or 48 h in cages containing healthy greenhouse- or field-grown male-sterile sorghum plants at anthesis, the levels of ergot severities on the panicles ranged from 0.5–90%, per panicle. The levels of ergot infection on greenhouse- and field-grown AT×623 exposed to ergot contaminated field-trapped males for 48 h ranged from 0–81.7%. Mean external contamination of laboratory-reared and field-trapped moths placed in a soapy wash was 1.4 × 105 and 4.7 ×104 conidia/ml, respectively. This study demonstrated that contaminated adult corn earworm could transmit the sorghum ergot from diseased to healthy panicles when environmental conditions are favorable for infection. Thus, migrating moths and other highly mobile pest species have the potential to transport C. africana over relatively large distances.

Indian Journal of Agronomy 58 (1): 54__62 (March 2013) Research Paper

System of rice (Oryza sativa L.) intensification (SRI) is a recent breakthrough in rice production technology. Tiller-production with healthy panicles, the key determinant of high yields under SRI, is variety and agronomic management dependant. This experiment was laid-out in a factorial RBD during rainy seasons of 2008 and 2009 in the tarai belt of northern India using fourteen treatments comprising of three irrigation schedules viz., irrigation at 1, 3 and 5 days after disappearance of ponded water (DADPW), two spacing intervals (20 cm 20 cm, 25 cm 25 cm) and two varieties (Pant Dhan 4, Arize 6444) under SRI, and two controls consisting of conventional culti- vation (CT) of two varieties. In 2008, irrigation effects were non-significant, while in 2009, irrigation at 1 and 3 DADPW caused 19.338.5% and 9.322%, respectively, higher number of filled spikelets/panicle, and recorded higher panicle weight and lower sterility percentage than 5 DADPW. Overall advantage in grain yield due to irriga- tions at 1 and 3 DADPW was 8.6 and 5.8%, respectively over 5 DADPW (5.82 t/ha). Wider spacing resulted in heavier panicles and higher grain yield than narrow spacing. Between two varieties, Arize 6444 produced higher number of filled spikelets in all type of tillers. SRI improved the panicle characteristics and increased grain yield by 16.9% over CT (5.22 t/ha). Number and weight of filled-spikelets/panicle of primary and secondary tillers were cor- related with grain yield. Under SRI, varieties which produce large number of primary and secondary tillers with heavier panicles and a few or no tertiary tillers should be planted as panicle weights of tertiary tillers did not show significant correlation with grain yield. Further, SRI-rice should be planted at 25 cm 25 cm spacing and irriga- tions should not be delayed beyond 3 DADPW.

Loose kernel smut for biocontrol ofSorghum halepenseinSaccharumsp. hybrids

Sporisorium cruentum teliospores and sporidia (cultured from teliospores with about 30-fold spore increase) caused about equal, although variable, levels of smut infection of individual Sorghum halepense plants when applied to the foliage. Teliospores were applied in a water–surfactant suspension (106 spores ml−1) at 935 L ha−1 and sporidia in a water-in-oil invert emulsion (about 107 spores ml−1) at 468 L ha−1. In crop interference studies, a single foliar application of teliospores to space-planted S. halepense plants in a first-year crop of Saccharum sp. hybrids caused about 55% infection (at least one smutted panicle per plant) but did not reduce the level of S. halepense infestation or substantially improve Saccharum yield compared to noninoculated plants. Smutted panicles usually appeared 30 to 60 d after the foliar treatment, but many culms on a plant produced only healthy panicles. Two applications of teliospores, either 7 d apart in one experiment or 1 yr apart in another, significantly increased (P = 0.05) smut infection over one application but generally did not improve Saccharum yield substantially over plots infested with noninoculated S. halepense. In contrast to foliar spray inoculation, S. halepense plants injected with teliospores in the seedling stage prior to transplanting to the field were 98% infected with smut and were much less competitive with the crop than noninoculated transplants. In host range studies using several S. bicolor genotypes injected with teliospores in the greenhouse, the ratios of resistant to susceptible were 17 to 2 for grain types and 16 to 5, with 2 intermediate, for forage types, showing that genotypes have a relatively high level of resistance to the disease. The result of these experiments indicate that loose kernel smut has potential as a biocontrol agent for S. halepense, but only if infection by foliar treatment can be improved to levels at least comparable to injection.

Micronutrient levels in malformed and healthy organs of mango

The concentrations of iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), and cobalt (Co) in malformed and healthy panicles of mango (Mangifera indica L.), leaves and shoots bearing them were analyzed at: (i) fully swollen bud, (ii) bud inception, (iii) fully grown panicles prior to full bloom, and (iv) full bloom over three consecutive years. The concentrations of Fe, Zn, Cu, Mn, and Co varied in malformed and healthy organs at various developmental stages. Malformed panicles exhibited lower levels of Fe, Zn, Cu, and higher Mn than healthy ones. The leaves on the shoots bearing malformed panicles showed higher levels of Fe, Mn, Cu, and higher Zn than the leaves on the shoots bearing healthy panicles. The shoots bearing malformed panicles revealed higher levels of Fe, Zn, Mn, and Cu than shoots bearing malformed panicles. The levels of Co in healthy and malformed organs did not differ much. The findings of the present study, therefore, seem to point that floral malformation in mango is not caused by the deficiency of these micronutrients.

Implication of Gibberellins in Head Smut (Sporisorium reilianum) of Sorghum bicolor

The head smut fungus, Sporisorium reilianum ([Kuhn] Landon and Fullerton), was shown to reduce plant height in infected Sorghum bicolor ([L.] Moench) plants. The major reductions occurred in the internodes nearest the panicle and were more severe in naturally infected than in inoculated plants. Less affected plants developed reproductively sterile panicles, and eventually smutted panicles developed phyllodied growths which progressed into leafy shoots. Extracts of smutted, sterile, and healthy (control) panicles of field-grown plants exhibited gibberellin (GA)-like activity in the dwarf rice bioassay. When extracts were purified and assayed with deuterium-labeled GA standards by gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM), GA(1), GA(3), GA(19), GA(20), and GA(53) were detected based on coelution with the standards, identical Kovats retention index values, and matching ion masses and relative abundances for three major ions. In addition, based on published Kovats retention index values, ion masses, and relative abundance values, GA(4), GA(7), GA(8), GA(14), GA(29), and GA(44) were tentatively identified. Quantitative analysis revealed that panicles of healthy control plants contained from 60 to 100% higher total concentrations of GAs than panicles of smutted plants. These comparisons were most striking for the early 13-hydroxylation pathway precursors GA(53), GA(44), and GA(19) but not for GA(20). Extracts of S. reilianum sporidia and culture medium exhibited GA-like bioactivity, and GA(1) and GA(3) were detected based on GC-MS-SIM assay with (2)H-labeled internal standards. Quantitative analysis of these GAs showed increasing concentrations from 4 to 7 to 10 days of culture and a decline at 20 days. This is the first GC-MS-SIM detection of GAs in a non-Ascomycete fungus, and the disease symptoms and quantitative data suggested that fungal infection may interfere with biosynthesis of GAs by the host plant.

Nutrient levels in malformed and healthy tissues of mango (Mangifera indica L.)

Samples of malformed and healthy panicles of mango (Mangifera indica L.) as well as leaves and shoots bearing them were collected at different stages of development (fully swollen buds, bud inception, fully grown panicles prior to full bloom and at full bloom) over two consecutive years and were analysed for their macro- and micronutrient status. In addition, malformed and healthy seedlings were collected and analysed. Malformed panicles were found to be significantly higher in N at all the developmental stages except at bud inception. Phosphorus and K also tended to accumulate in malformed panicles at later stages of their development. In general, malformed panicles exhibited lower levels of P, K and Ca than healthy panicles. The differences in levels of Mg and S in malformed and healthy panicles were not significant. All micronutrients were in much lower concentrations in malformed panicles except for Mn which appears to accumulate in malformed panicles particularly at the early stages of development. The leaves on the shoots bearing malformed panicles also showed a tendency to accumulate N, while P, Mg and S were always higher in leaves on shoots bearing healthy panicles. The leaves on shoots bearing healthy panicles had lower levels of Fe, Cu and Mn, whereas levels of Zn and B tended to be higher in leaves on shoots bearing malformed panicles. The nutrient concentration differences between the two kinds of shoots were generally nonsignificant (P=0.05), except for K and S which were significantly lower in shoots bearing malformed panicles. The shoots bearing malformed panicles showed significantly (P=0.05) higher levels of almost all nutrients compared with shoots bearing healthy panicles. Vegetative malformation was found to be associated significantly (p=0.05) with higher amounts of all nutrients except Ca which was significantly higher in healthy seedlings. The present study, therefore, seems to point to lower Ca as one of the pre-disposing factors causing malformation in mango.

In vivo Role of Indole‐3‐acetic Acid, Gibberellic Acid, Zeatin, Abscisic Acid and Ethylene in Floral Malformation of Mangifera indica L.*

Abstract The endogenous levels of indole‐3‐acetic acid (IAA), gibberellic acid (GA3), zeatin, abscisic acid (ABA) and ethylene were studied in panicles/shoots of Dusheri mango at four stages viz., (I) fully swollen buds; (II) bud inception; (III) fully grown panicles prior to full bloom and (IV) fully grown panicles at full bloom, for three consecutive years. The malformed panicles and the shoots bearing malformed panicles (SBMP) possessed lower levels of IAA in relation to healthy panicles and shoots bearing healthy panicles (SBHP) at stage I, II, III and IV. The malformed panicles and SBMP maintained lower levels of GA3 than healthy panicles and SBHP at stage I. However, the converse was true for stages II, III and IV. The malformed panicles and SBMP exhibited higher levels of zeatin compared with their healthy counterparts at the four developmental stages. Likewise, the contents of ABA and ethylene were also higher in malformed panicles and SBMP than healthy panicles and SBHP at all the stages. It is concluded that floral malformation is associated with malformin stimulated ethylene production and higher levels of ABA, gibberellic acid, zeatin and lower levels of IAA.

Floral malformation, yield and fruit quality ofMangifera indicaL. in relation to ethylene

A three-year study of malformation in mango (Mangifera indica L.) revealed significantly higher levels of ethylene (46%, 145%, 67% and 34%) in malformed panicles than in healthy ones at development stages (I) fully swollen buds, (II) bud inception, (III) full grown panicles prior to full bloom, and (IV) full grown panicles at full bloom, respectively. Similarly, the shoots bearing malformed panicles showed significantly higher levels of ethylene (110%, 90%, 106% and 104%) over shoots bearing healthy panicles at the four developmental stages. Leaves borne on shoots bearing malformed panicles had significantly more ethylene (198%, 120%, 79% and 159%) than leaves on shoots bearing healthy panicles at all four stages. In a two year trial, exogenous sprays of ethephon at 400 ppm a.i. at bud inception stage were more successful in reducing floral malformation (8.9% and 10.2%) than ethephon sprays of 300 ppm, 500 ppm and water control sprays. Highest yields were obtained following application of ethephon (400 pp...

Occurrence of malformin-like substances in malformed panicles and control of floral malformation in mango

Ether-soluble extracts from malformed panicles showed 2 malformin-like substances when assayed by mung bean growth test. Three malformin-like substances were found on the chromatograms using the maize root curvature test. Developing malformed panicles were sprayed 3 times with 2240 mg l −1 glutathione or 2110 mg l −1 ascorbic acid. Panicles thus treated appeared healthy 15 days after treatment and produced the same number of fruits as healthy panicles.