RÉSUMÉ
The current study was conducted to identify the best parents with good agronomical features and contrasting characteristics for sucking pest resistance to develop a population that can be used for Quantitative Trait Loci mapping of resistance component traits. Initial attempts at this university have enabled to identify of five potential parents (viz., KC3, NDLH 1938, CO18, K12, and RG8) with improved sucking pest resistance and yield characters and they were crossed with the recently released high-yielding variety CO-17, which is also suitable for high-density planting. All these six parents were evaluated for fiber yield and quality traits besides anatomical characters such as trichomes density, length, width, and sharpness that confers sucking pest resistance and genotyped with 200 Simple Sequence Repeats markers that span the entire genome. Efforts have been dedicated to the careful selection of optimal parents, namely CO17 and KC3, each possessing distinct traits related to resistance against sucking pests and also fiber quality characters in addition. This strategic approach aims to combine their contrasting genetic components for sucking pest resistance, to develop a new generation of plants that exhibit heightened resilience to these types of pests. CIR139, a polymorphic SSR marker of these two parents was used to fix the true hybrids which were advanced to generate an F2 mapping population. This population is believed to be useful for QTL mapping of anatomical features that confer sucking pest resistance such as trichome length, density, breadth, and sharpness besides fiber yield and quality traits.
RÉSUMÉ
Crepe jasmine or East Indian rosebay or pinwheel flower, Tabernaemontana divaricata originated from India is a popular large shrub or a small tree grown in tropical and sub-tropical gardens for its beautiful glossy foliage and mild fragrant waxy white, ornamental flowers. It produces flowers throughout the year, except in winter but profusely during summer season. Rather than the opened flowers, the unopened flower buds are commonly used as an alternate to Jasminum sambac buds in off-season. The present investigation was carried out at the Department of Floriculture and Landscape Architecture, Horticulture college and Research Institute, Tamil Nadu agriculture university, Coimbatore during 2022-2023. Randomized Block Design was used with three replications with the objective of investigating promising genotypes of Tabernaemontana divaricata, collected based on the type of petals from different locations for loose flower production. In the study totally 12 accessions were collected and named from Acc. No. 1 to 12. They are evaluated for their vegetative and floral parameters such as plant height, leaf length, leaf width, no. of branches, plant spread in EW & NS direction. Floral parameters include bud length, bud diameter, stalk length and no. of petals/flower. Out of the collected accessions, Acc. No. 2 & 5 are suitable for veni arrangement and Acc. No.10 & 11 are suitable for garland making. Buds of acc. No.4 & 6 are similar to Jasminum sambac and J. auriculatum buds.
RÉSUMÉ
Rapid and precise identification of three sex types (male, hermaphrodite and female flowers) is the key in achieving good returns in papaya (Carica papaya L.) cultivation. This study presents a simple, reliable, fast and cost-efficient DNA isolation protocol and a rapid and precise method of sex determination in papaya. Three DNA isolation protocols viz., CTAB method, Modified Dellaporta method and BioBasic DNA isolation kit were comparatively evaluated for their simplicity, economic, DNA quantity and purity. Among them, CTAB method was regarded as relatively economic, with a cost of Rs. 11.80943 per sample with higher amount of DNA (4667.4 µg/ µl). However, it was noticed that DNA isolation with the BioBasic kit was fastest method, which took only 6 hours 7 minutes. On the other hand, relatively better DNA purity was noticed with the Modified Dellaporta method (average ratio of absorbance at 260 nm and 280 nm range between 1.8-2.0) and yielded clear, intact and distinct DNA bands. Hence, Modified Dellaporta method is suggested as an ideal DNA isolation protocol for papaya. Molecular markers (such as SCAR derived from RAPD T12, W11, NAPF-2 and PKBT-4) were employed in this study to identify the sex type and they have successfully distinguished between male and hermaphrodite plants in both dioecious and gynodioecious varieties; especially, NAPF-2 has successfully distinguished male in dioecious varieties. Evaluation of different kinds of molecular markers has shown that the SCAR marker T12 can be used as reliable marker for rapid and precise identification of papaya sex type.
RÉSUMÉ
Aim: Salt stress adversely affects plant growth and development. Various mitigating strategies have been employed to enhance the adaptability of plants to salt stress. The present study was conducted with the objective of evaluating the recently developed CO55 rice variety's ability to withstand salt-induced stress during seedling growth. This evaluation included foliar spraying of plant growth promoting substances like melatonin, salicylic acid, silicon, and selenium, along with the identification of effective plant growth-promoting substances that exhibit tolerance to salinity. This study is required to develop salt-tolerant varieties capable of withstanding salinity stress during the seedling stage. The seedling stage is more susceptible to salinity, and also to increase the growth and yield of rice, thereby satisfying the country's agricultural needs.Study Design: Completely randomized design.Place and Duration of Study: Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore; March-April 2023.Methodology: In the hydroponics experiment, the CO55 rice variety was subjected to foliar spraying of various plant growth promoting substances such as melatonin, salicylic acid, orthosilicic acid, and sodium selenate. Parameters like leaf drying score, osmotic potential, osmotic adjustment, sodium content, potassium content, and Na+/K+ ratio were assessed. One-way ANOVA was used to analyze the data.Results: Specific pairwise differences between means were assessed at the 0.05 significance level using Fisher's least significant difference (LSD) test. Among the treatments applied, salicylic acid recorded the highest potassium content (3.94%), and the lowest potassium content (2.60%) was found in orthosilicic acid. On the other hand, from the standard evaluation score, it was observed that CO55 rice variety seedlings were found to be tolerant when treated with salicylic acid, whereas it was susceptible under orthosilicic acid treatment.Conclusion: Observations indicated that foliar application of salicylic acid at the concentrations of 50µM and 100µM exhibited higher tolerance towards salinity during the seedling growth stages.
RÉSUMÉ
Cotton is the most important global cash crop which controls economy of many nations. Global sustainability of cotton yield is one of the major challenges for meeting impending threats under climate change. Though India is one among the leading countries in cotton production, the supply is not enough considering the increasing demand. Scientists across the Globe are indulged in developing new lines and cultures with capacity to produce more yields. In this context, here, we have made an attempt to study the growth, physiology, and yield traits of cotton culture - TCH 1819 before its release (now released in the name of CO 17) by different chemical treatments. Observation on the leaf gas exchange traits, leaf parenchymal cells distinguished the source sink relationship of the culture. Chemical manipulation by growth retardants reduced the gibberellins content and modified the foliage structure. By characterizing the physiological potential through manipulation by growth retardant (Mepiquat chloride (0.015 %)) increased the yield by 30%. The traits identified in this study are potential indicators in breeding programme before releasing the variety.