Genetic Diversity Analysis in Cucumber (Cucumis sativus L.) Based on Morphological Traits

Evaluation of fifteen diverse genotypes of cucumber was carried out in a randomized complete block design for studying genetic divergence. Presence of wide genetic diversity, among the genotypes studied was confirmed by using Mahalanobis D2 statistics. Based on the interactions genetic distances of cucumber genotypes had grouped into five separate clusters inferring that the genetic divergence between them was quite high. The germplasm were so divergent, that only six genotypes were grouped in cluster V and three genotypes in each cluster I and III. The two genotypes SKY/AC-270-613481 and JB/11-091-613462 were grouped as cluster II and the genotype Tripura local was so divergent in all the characters that they were allotted as a separate group as cluster IV. Cluster mean analysis proclaimed that, genotypes in cluster I recorded maximum value for vine length (3.36 m), number of leaves per plant (43.85), number of branches per plant (12.98), leaf area (144.71 cm2), number of female flowers per plant (20.30), fruiting period (52.20 days), fruit set (89.10 %), average fruit weight (214.72 g), number of fruits per plant (19.00), fruit yield per plant (2.50 kg), fruit yield per ha (31.23 t/ha), rind thickness (2.79 mm) and flesh thickness (3.02 cm), whereas, same cluster I recorded minimum value for traits viz., internodal length (6.55 cm), days to appearance of first male flower (30.34 days), days to appearance of first female flower (31.81 days), node number at which first female flower appeared (4.00), days to first harvest (41.22 days) and number of seeds per fruit (211.69) which are negatively desirable characters in the crop production and crop improvement programme.

Evaluation and Characterization of High Yielding Cassava Mosaic Resistant Variety YTP2

The cassava variety YTP2 (Me 681) has been developed through selection from Thondamuthur type at Tapioca and Castor Research Station, TNAU, Yethapur. The performance of YTP2 in the Adaptive Research Trial (ART) and On Farm Trial (OFT) in the farmer’s field inferred that this new variety is well adapted to cassava growing districts of Tamil Nadu. In addition to the above, YTP2 was found to be resistant to cassava mosaic disease incidence (CMD). Plants are erect, medium growing and non-branching type and suitable for growing under irrigated and rainfed conditions. The internodal length is shorter and the leaf size is medium with sufficient canopy. The leaves of the plants droop down to reduce the transpiration loss which is more advantageous to overcome or escape from drought and heat stress during summer season. It is a dual purpose variety wherein the tubers contain high starch content which is much favourable for the manufacture of starch, sago and also suited for table purpose. The overall performance of this variety showed higher tuber yield (42.20 t ha-1) and starch content (28.40%) which is 15.94% and 18.20% increase over the check varieties YTP1 and H226 respectively. The results of DNA fingerprint data involving SSR markers (SSRY235, NS169 and NS928) showed that it is genetically distinct from the existing commercial varieties viz., YTP1, H226 and Sree Athulya.

Effect of aging of Cladding Material on Crop Yield under Greenhouse Cultivation

Agriculture is the basis of our economic activity. For improving agricultural production greenhouse technology was developed to prevent adverse climatic conditions. Even though higher yield and profit were obtained from greenhouse production compared to open field cultivation farmers were not satisfied with this technique due to the drastic reduction of crop yield with the aging of cladding material. To test this, an experiment was conducted in the instructional farm of Kelappaji College of Agricultural Engineering and Technology (KCAET), Tavanur, Kerala during the period from April to June 2021. Amaranthus variety CO1 was planted inside two greenhouses where one is having cleaned cladding material and the other is an old one. Microclimatic parameters and the biometric observations of crop in both conditions were compared. Mean monthly values of temperature and light intensity were higher inside the cleaned greenhouse than the old one while relative humidity was higher inside the old greenhouse. Crop growth parameters were higher inside the cleaned greenhouse than the old one except the internodal length. From this study, it was clear that the aging of cladding material has a significantly higher influence on crop performance under greenhouse.

Morphological and Physio-Biochemical Responses of Watermelon Grafted onto Rootstocks of Wild Watermelon [Citrullus colocynthis (L.) Schrad] and Commercial Interspecific Cucurbita Hybrid to Drought Stress

This study aimed to assess the morphological and physio-biochemical responses of a commercial watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) cv. ‘Crimson Sweet’ grafted onto a drought-tolerant rootstock of wild watermelon (bitter apple, Citrullus colocynthis (L.) Schrad, ‘Esfahan’) in comparison with an ungrafted ‘Crimson Sweet’ watermelon or one grafted onto a commercial interspecific Cucurbita hybrid (Cucurbita maxima Duch. × Cucurbita moschata Duch.) rootstock (‘Shintoza’) under water stress. The experiment was conducted in pots under a controlled environment in a greenhouse, and water stress was imposed by maintaining moisture level in pots at 100% (well water (WW)) or 50% (water deficit (WD)) of container capacity (CC). WD significantly decreased most of the morphological traits in ungrafted and grafted plants, while the decrease in growth traits was lower in grafted plants than ungrafted plants. The response of grafted plants onto wild watermelon rootstock (‘Esfahan’) for most of the affected parameters (shoot fresh and dry weight, vine length and internodal length) was, however, comparable to those grafted onto commercial Cucurbita hybrid rootstock (‘Shintoza’). Plants grafted onto bitter apple (wild watermelon) exhibited a relatively lower decrease in growth and biomass, besides showing higher antioxidant activity (e.g., guaiacol peroxidase) concomitant with the lower accumulation of malondialdehyde and electrolyte leakage in the leaf tissues in comparison with ungrafted plants. The overall growth performance, as well as those under water stress conditions in commercial rootstock-grafted watermelon, was related to its better plant water status (e.g., high relative water content) which was likely ascertained by its greater root efficiency. This suggests that watermelons grafted onto bitter apple rootstock and Cucurbita hybrid rootstock were constitutively more resistant to drought, with higher efficiency in mitigating oxidative stress than ungrafted treatment. The above findings demonstrated that bitter apple, a well-adapted desert species, can be used as an alternative rootstock to commercial rootstocks (e.g., ‘Shintoza’) for watermelon grafting under water stress conditions. In addition, bitter apple rootstock can be involved in rootstock breeding programs to improve drought tolerance in watermelon.

Development of Morphological Descriptors For Characterization of Teak (Tectona Grandis L. f.) Seed Sources In India

Teak (Tectona grandis L.f.) plantations in India has been intensified in the recent past yet, morphological descriptors for teak is still lacking. Hence, this study aimed to develop descriptors using morphological traits. Among 30 seed sources collected from different states of India, 24 morphological descriptors viz., leaf length, leaf width, presence of petiole, petiole length, leaf shape, shape of leaf apex, shape of leaf base, leaf texture, phyllotaxy, leaf attitude, leaf margin, leaf margin undulation, leaf brightness, leaf venation, leaf main vein, leaf veins, leaf vein colour, leaf colour, leaf pubescence, young leaf colour, number of internodes, internodal length, trunk spots and trunk colour were developed based on leaf and stem characteristics. Subsequently, genetic similarity among the sources were estimated by Jaccard similarity index and cluster analysis was performed by Unweighted Pair Group Method with Arithmetic mean (UPGMA) method.

A STUDY ON CORRELATION AND ASSOCIATION OF CHARACTERS OF EXACUM TETRAGONUM ROXB. IN NORTH KERALA, INDIA

Western Ghats provide asylum to several endemic plants. Exacum tetragonum Roxb. is one of the important endemic herbs inhabiting the hilly tracts and midlands of Kerala, the state of India located towards the south-western side of the Western Ghats. The plant is used for treating fever, stomach disorders, gout, diabetics, and eye diseases. It is also found associated with antioxidant, anti-inflammatory, anti-helminthic and anti-hyperglycemic activities. Correlation and association of characters of this important medicinal plant was analyzed based on the observations on thirteen salient morphological characters recorded from twenty three populations of the species distributed across Malappuram, Thrissur, Kozhikode and Palakkad Districts of Kerala State of India. All the characters studied such as plant height, number of leaves, number of flowers, number of inflorescences, leaf length, leaf breadth, peduncle length, pedicel length, internodal length, leaf area, mean stem girth, number of branches and fresh weight of plants showed statistically significant variations between the populations. Number of flowers showed significant positive correlation with the maximum number of characters (ten characters) whereas number of leaves showed significant positive correlation with the minimum number of characters (two characters). By factor analysis, two factors could be extracted and fresh weight of plant was found to be the lead character. Significant variability with regard to morphological characters indicates the strong genetic base of the plant species in the field. However, drastic changes in its habitat for various reasons can certainly cause severe threats to its continued existence and hence appropriate actions to conserve the natural habitats of this species are vital.

Character Association and Path Analysis for Yield Components and Biochemical Traits in Maize (Zea mays L.) Genotypes

Background: Grain yield is a complex character so direct selection for yield as such can be misleading. Keeping in view, the present study aimed to assess the path coefficient analysis with correlation coefficient technique to establish the direct and indirect relationship between the yield and its component. Methods: The present investigation carried out during kharif 2019 at Centurion University of Technology and Management, Odisha in randomized complete block design with 3 replication involving 20 maize genotypes. Data were collected from five randomly selected plnts on 20 agromorphic and biochemical traits. All the biochemical analysis estimated from leaf sample following standard procedure. Result: The traits shelled grain weight, cob diameter, number of grains per cob and anthesis silking interval were found to possess significant association in disirable direction with five ear weight at both genotypic and phenotypic levels. None of the biochemical trairts establishing significant positive association with yield. Highest positive direct effect on 5 ear weight was noticed by shelled grain weight (1.108) followed by phenols (0.115), internodal length (0.106) and days to 50 percent anthesis (0.102) indicating that the selection for these characters were likely to bring about an overall improvement in grain yield directly.

Internodal Analysis of Avicennia marina in the Western Arabian Gulf

The growth of Avicennia marina (A. marina) was not previously assessed using internodal analysis in the Western Arabian Gulf. The node production in 40 branches/axillary shoot in Syhat city, Saudi Arabia, ranged from 6 to 9 nodes y–1. Moreover, the annual cycles of the internodal length represent the branch growth rate in centimeters per year (ranged from 12 to 43 cm; median of 19 cm) for minima to minima point and (from 15 to 46.5 cm; median of 25.5 cm) for maxima to maxima point. The results obtained in this study are fundamental for various applications, ranging from the planning of restoration and monitoring activities to reproduction estimates and establishing a useful baseline to assess responses to climate change via simple measurements. In particular, mangrove species are important as nurseries for many species for food and shelter, carbon sinks, and coastal protection.

Varied shoot growth in rice plants across different developmental stages under induced flooding

All the modern high yielding rice varieties precariously respond to flooding, although a number of landraces are tolerant to wide range of flooding with penalty of low yield. Stage-specific flood tolerance experiment was performed at three different conditions for three different growth stages from germination to vegetative stage for five such selected landraces, along with a flood-resistant quiescent variety (FR13A), a sensitive line (IR42), an improved cultivar (Swarna) and one Sub1 loci introgressed improved line (Swarna-Sub1). Different morpho-physiological traits at each stage were observed and genotypes were evaluated by these quantifiable traits to understand their underwater performance. All the studied landraces represented strong seed germination and faster coleoptile elongation than FR13A, Swarna and Swarna-Sub1 under water. At early seedling stage var. Kumrogarh embraced with highest number of seedlings with leaves and extended greater leaf portion above the water. Shoot elongation associated with internodal and petiole/blade elongation and well developed aerenchyma tissue facilitated vegetative tissues to survive. In this stage, Kumrogarh had highest plant height but Bakui had highest internodal length which indicated that kumrogarh might have the greater leaf sheath or blade elongation up to day 21 and also smaller increase (%) in air cavity formation at day 21 which made the stem to be upright devoid of lodging. All these results indicated that the studied landraces are the potential resources for submergence avoiding response for all the stages and should be elaborately investigated for future breeding programme. The rice line kumrogarh may be one of the potent traditional rice which can withstand all sorts of submergence by virtue of all the stage-specific attributes under submergence stress.

Morphological Characterization, Trait Variability and their Association, and Diversity Analysis Among Yard Long Bean (Vigna unguiculata (L.) Walp. subsp. Sesquipedalis (L.) Verdc.) Genotypes

Genetic variability has been greatly valued in yard-long bean, due to their narrow genetic base. To diversify the genetic base, yard long bean genotypes were evaluated to quantify the variation, to assess the extent of association between the yield complaint traits, diversity and for their utilization in crop improvement programmes. High phenotypic and genotypic coefficient of variations, heritability coupled with genetic advance over mean were observed most of the traits except internodal length, days to first and 50 per cent flowering, days to first and last picking, seeds per pod. Correlation and path analysis of variables namely pod length, pod width and pods per plant contributes high positive significant association with pod yield per plant, and maximum direct and indirect effect recorded for pods per plant, green pod length and green pod width. The genotypes were grouped into 12 clusters, the maximum divergence recorded between genotypes of Cluster XI and Cluster XII for traits pod yield per plant, vine length and yield per plot and pod length contributed high towards total divergence, the genetically diverse genotype of these clusters aids in the creation of larger recombinants, and would be an aid in the genetic improvement of yard-long bean genotypes.