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Late blight disease caused by the fungus Phytophthora infestans is the main yield limiting factor amongst the diseases of potato in India and across the globe. Potato Cyst Nematode/PCN (Globodera spp.) is another biotic factor of economic importance and is a quarantine organism. Exploitation of genetic resistance is the most preferred management strategy. In the present study, indigenous potato genotypes collected from different parts of the country along with checks were evaluated for their resistance against late blight under natural epiphytotic field conditions and in laboratory under artificially inoculated conditions including detached leaf and tuber slice assays and PCN through Root ball technique during 2020-2023. The converted field scale values i.e. average AUDPC value ranged from 7 in highly resistant genotype Rangpuria to 1596 in susceptible accession AGR/56. The field blight response was comparatively more correlated (r =0.63) with susceptibility levels measured in the detached leaf assay compared to that with tuber slice assay (r =0.48). Genotypes Kanpuria Safed, JG-1, Rangpuria and Desi Aloo showed resistance to late blight both under laboratory and field conditions. For PCN, Garlentic, Jeevan Jyoti and JG-1 have combined resistance (0 female/root ball) over the years to both the species. Majority of the studied genotypes have medium to high pollen viability with desirable tuber traits and yield advantage. The identified resistant genotypes excel their usage as parental lines in breeding for biotic stress resistance specifically for late blight and PCN. [ABSTRACT FROM AUTHOR]

Tomato, an important vegetable crop due to its utility as raw, cooked and processed form of food, requires improved cultivar with high nutrition and yield to meet out global demand in changing agro-climatic conditions. The mutagenesis is one of the most important techniques to create genetic variability and identification of economically important traits towards the crop improvement. Therefore, the mutagenic effect of various concentrations of hydroxyl amine and sodium azide were studied on tomato var. PKM 1 for the qualitative and quantitative traits of economic importance. The seeds of tomato were obtained from Ryoth’s Depot Kurnool, Andhra Pradesh, India and treated with the different concentrations of sodium azide (SA) and hydroxyl amine (HA) 2 mM, 3 mM, 4 mM, 5 mM and 0.1, 0.15%, 0.2, 0.25%, respectively) for four hours. Study on germination per cent, seedling height, root length and pollen viability was carried out in lab and for growth parameters. M1 generation was grown in the field. The mutagens hydroxyl amine (0.1%) and sodium azide (2 Mm), showed least reduction in parameters and with increase the concentration of both chemicals, decline was noted. Highly significant differences were observed in the treatments with respect to the studied traits (seed germination, seedling survival, seedling height, root length, pollen viability, leaves per seedling and height at maturity, branches per plant and fruits per plant. The present study concluded that mutagens had detrimental effects along with creating variability. Hence, hydroxyl amine (0.1%) and sodium azide (2 Mm) could be utilized to induce variability for the improvement of tomato. [ABSTRACT FROM AUTHOR]

The present research investigated the impact of plant growth regulators in mitigating the effects of heat stress in tomato (Solanum lycopersicuwi L.) genotype LST-6 and cultivar Punjab Varkha Bahar-4. In north India, the temperature in the summer season ranges between 25-45 °C and temperature above 28 °C leads to heat stress in plants and negatively affects the reproductive stage of plants. Considering this, we subjected the plants to varying concentrations of GA3 (10, 20, 30 µg/mL) and 4-CPA (15, 45, 75 µg/mL). GA3 application took place three weeks after transplanting, while 4-CPA was administered during the anthesis stage. We recorded observations from both control and treated plants, with a 10-day gap between each spray treatment. The application of plant growth regulators (PGRs) enhanced the plants' ability to withstand high temperatures by improving photosynthetic efficiency, as evidenced by increased chlorophyll and carotenoid levels in the leaves. The level of different biochemical constituents (total protein, starch, total soluble sugars, phenol and proline content) also increased in PGRs treated plants. Application of GA3 and 4-CPA also enhanced the membrane thermostability and reduced lipid peroxidation. The PGRs treated plants exhibited increased plant height, leaf area, pollen viability, fruit set, number of fruits per plant and fruit weight, ultimately improving yield. GA3 and 4-CPA application also increased the total soluble solids, lycopene content and titratable acidity in tomato fruits. Thus, overall improvement was observed with the application of PGRs; however, 75µg /mL 4-CPA was most effective in imparting thermo tolerance. [ABSTRACT FROM AUTHOR]

• The susceptible genotypes exhibited the highest levels of lipid peroxidation and lesser magnitude of proline increase than the tolerant ones during reproductive cold stress in chickpea. • Proline and pollen load can be used as prominent phenotypic markers in screening for cold tolerance in chickpea breeding programme. • The breeding lines GL29183-P1, GL29183-P2 and GL29183-P3 and cultivar PBG5 can be extensively evaluated in cold prone areas to identify any line for release for general cultivation. Cold stress is one of the most important abiotic stresses affecting chickpea production in Northwestern India. Further, the short-duration varieties are more susceptible to cold injury as their reproductive phase coincides with the cold spell of this zone. So, enhancing the cold tolerance of the host plant is the only viable option to resolve this issue in chickpea. The present study involved a set of 13 advanced breeding lines (with differential cold sensitivity) and three reference varieties (GPF2, PBG5, and PBG7) of chickpea which were exposed to cold stress at the reproductive stage under field conditions during the winters of 2019–20 and 2020–21. Various physiological and biochemical parameters such as proline, electrolyte leakage, photosynthetic pigments, lipid peroxidation, and 2, 2-diphenyl-1- picrylhydrazyl (DPPH) activity were measured before and after exposure to cold to delineate the mechanism of tolerance in these genotypes. Significant genotypic variations were observed for the above-mentioned traits in both years. The genotypes GL27059 P2, GL 28202-P1, and GL28202-P2 exhibited the highest lipid peroxidation and lesser magnitude of proline increase during reproductive cold stress on a pooled basis. These genotypes performed poorly for yield traits like pod set percent, filled pods plant –1, total seeds/ plant, and seed yield/plant and hence were susceptible to cold stress. Further, a significant reduction in reproductive function of male gametophyte i.e. pollen viability and pollen load under cold stress was also observed in these susceptible genotypes. In contrast, tolerant line GL29183-P2 had significantly more pollen load and pollen viability contributing to better yield performance (viz., higher flowers/plant, pods/plant, and maximum pod set percent) among the studied advanced breeding lines. Based upon the pooled analysis, the reference variety PBG5 outperformed in yield attributes i.e., total flower/ plant, total filled pods/plant, and had a significantly higher yield than GL29183 under cold stress at the early reproductive stage. A significant increment in levels of proline (125–160%) on exposure to cold spell was observed in genotypes, GL29183 and PBG5, which contribute toward cold tolerance. Thus, an increase in proline along with maintenance of pollen load can be used as prominent phenotypic markers in screening for cold tolerance at the reproductive stage in chickpea. [ABSTRACT FROM AUTHOR]

Clerodendrum colebrookianum Walp. and Clerodendrum infortunatum L. are well known for their medicinal uses in treating various human ailments traditionally. Pollen biology study was done in both plant species to decipher pollen viability, in vitro pollen germination, and pollen storage in varied temperature conditions. Pollen viability tests was done by 2, 3, 5-triphenyl tetrazolium chloride (TTC test) for which pollen grains were collected at the anthesis stage that ascertained high viability, ranged between 71.97%±4.30 % in C. colebrookianum and 81.63%±3.23 in C. infortunatum. In vitro pollen germination was conducted under different hormones (IBA, IAA, GA3, and Kinetin) with concentrations of 100 mg L-1, 200 mg L-1 and 300 mg L-1. Highest germination percentage of 52.10±5.30% and 61.91±1.76% in GA3 (200 mg L-1) was the most suitable growth hormone concentration for inducing in vitro pollen germination in both Clerodendrum species. Statistically, the response of all the concentrations of treatments, sucrose, and hormones, with their time on in vitro pollen germination of C. colebrookianum and C. infortunatum was found significantly different (p<0.05). In contrast, non-significant differences were recorded for in vitro pollen germination between the medicinal plant species. Pollen storage under temperature gradient conditions exhibited a similar trend in the viability for both C. colebrookianum, and C. infortunatum, i.e., the pollen remained viable up to 28 days at -20°C and 6°C, respectively. This study will be helpful in future breeding, hybridization, and conservation efforts for both the Clerodendrum species. [ABSTRACT FROM AUTHOR]

Salacia is a genus of flowering plants in the family Celastraceae, consisting of woody climbers distributed in tropical America, Africa, and Asia. In India it is represented by 21 species, of which 15 occur in peninsular India. Most species of the genus have been used in traditional medicine, mainly the Ayurvedic system. Apart from overexploitation for medicinal purposes, the low fruit set and infestation of seeds have affected natural regeneration, and led to the rarity of Salacia species in their natural habitats. The reproductive biology of Salacia oblonga and S. gambleana was studied for the first time to understand the reproductive constraints of these threatened and medicinally important species. The flowering phenology, pollen viability, germination, stigma receptivity, and insect-pest interaction were analyzed. The obligatory entomophily coupled with insufficient pollinators and seed pest infestation were found to be the main reproductive constraints responsible for the low fruit set and poor natural regeneration of these species. [ABSTRACT FROM AUTHOR]

Background: Heat tolerance is becoming increasingly important where maize is grown under spring season in India which coincide with grain filling stage of crop resulting in tassel blast, reduced pollen viability, pollination failure and barren ears that causes devastating yield losses. So, there is need to identify the genomic regions associated with heat tolerance component traits which could be further employed in maize breeding program. Results: An association mapping panel, consisting of 662 doubled haploid (DH) lines, was evaluated for yield contributing traits under normal and natural heat stress conditions. Genome wide association studies (GWAS) carried out using 187,000 SNPs and 130 SNPs significantly associated for grain yield (GY), days to 50% anthesis (AD), days to 50% silking (SD), anthesis-silking interval (ASI), plant height (PH), ear height (EH) and ear position (EPO) were identified under normal conditions. A total of 46 SNPs strongly associated with GY, ASI, EH and EPO were detected under heat stress conditions. Fifteen of the SNPs was found to have common association with more than one trait such as two SNPs viz. S10_1,905,273 and S10_1,905,274 showed colocalization with GY, PH and EH whereas S10_7,132,845 SNP associated with GY, AD and SD under normal conditions. No such colocalization of SNP markers with multiple traits was observed under heat stress conditions. Haplotypes trend regression analysis revealed 122 and 85 haplotype blocks, out of which, 20 and 6 haplotype blocks were associated with more than one trait under normal and heat stress conditions, respectively. Based on SNP association and haplotype mapping, nine and seven candidate genes were identified respectively, which belongs to different gene models having different biological functions in stress biology. Conclusions: The present study identified significant SNPs and haplotype blocks associated with yield contributing traits that help in selection of donor lines with favorable alleles for multiple traits. These results provided insights of genetics of heat stress tolerance. The genomic regions detected in the present study need further validation before being applied in the breeding pipelines. [ABSTRACT FROM AUTHOR]

Pumpkin is a major cultivated crop particularly in north eastern states of India that depends on insects for the pollination, as the pollens of these plants are large sized and sticky. In the present study, field and lab experiments were conducted to determine the efficiency of the pollinators of pumpkin based on their diversity, relative abundance and foraging activity. Total four hymenopteran insect pollinators were observed in field viz., bumble bee, little honey bee, Indian honey bee and Digger bee. On the basis of abundance and relative abundance bumble bee was identified as most abundant pollinator of pumpkin with 69.69 per cent mean relative abundance as other pollinators mean relative abundance was less than 25 per cent and it was only 3.49 per cent for Indian honey bee. Foraging speed and foraging rate of bumble bee was 7.13 sec/flower and foraging rate was 3.80 flower/minute. To ensure the efficient pollinator of pumpkin flower, pollen carrying capacity, pollen deposition and percent deposition of viable pollen was studied for all the pollinators in field and laboratory condition. The pollen carrying capacity of pollinators ranged from more than 7 mg to 1 mg. It was highest for bumble bee which was 7.33 mg followed by little honey bee (6.66 mg) and least pollen carrying capacity was observed in Digger bee (1.67 mg). Pollen depositions by pollinators on stigma in a single visit was again highest for bumble bee (565 pollen grains) with maximum number of viable pollen deposition 224.33 pollen grains out of which 39.7 per cent pollen was viable. So on the basis of above result it can be concluded that bumble bee was the most abundant and most efficient pollinator of pumpkin. [ABSTRACT FROM AUTHOR]

Gregarious flowering of Dendrocalamus sikkimensis clumps located at Kerala Forest Research Institute campus and Field Research Centre, Veluppadam, Thrissur, Kerala initiated in August 2009. Observations were made on floral morphology, anthesis, pollination, pollen viability and germination and post flowering behaviour. The flowers were dichogamous, protogynous and closed. The inflorescence was a large leafy panicle, with stiff nodose branches bearing large globose heads. Pollens were numerous and monoporate. Ovary was sub globular, hairy with club shaped stigma. Anthesis occurred from 6.00 am onwards. High pollen viability (92 %) was observed in acetocarmine staining and in vitro pollen germination ranged from 3-74 per cent. The pollination was anemophilous. Flowering was followed by abundant seed production and subsequent drying and death of the culms. [ABSTRACT FROM AUTHOR]

Reproductive biology of three dominating mangrove species Rhizophora mucronata, Ceriops decandra and Avicennia marina from the Indian Sunderbans were studied. A comparative account on all floral parts revealed that as the bud progresses to completely open, the length of androecium surpassed the length of gynoecium and the anther matured first thus showing protandrous nature and favouring cross-fertilization. A study of pollen grain viability revealed that all of them produces fairly good amounts of viable pollen grains in their natural condition. The pollens showed their maximum viability late in the morning till early noon. The stigma showed peak receptivity after three days of flower opening in C. decandra and four days of flower opening in R. mucronata and A. marina. All the species showed out-breeding mechanism of pollination. The fruit setting percentage obtained by xenogamy was the highest and autogamy failed to show any result in all the three genera. Although Ceriops decandra and Avicennia marina showed very limited fruit set with geitonogamy, these two species can be called facultative out-crossers, while Rhizophora was obligate outcrosser in nature. The study on floral structure, pollen viability along with stigma receptivity of the investigated taxa guided to maximum exploitation of reproductive behavior for rising artificial and natural plant population in addition to build up a future research strategy in ecosystem conservation. [ABSTRACT FROM AUTHOR]

The study in relation to loral biology conducted at Ludhiana (central plain region of Punjab, India) exhibited that Jatropha curcas lowered for two seasons viz. April till June and July till November. Male and female lowers opened 7 to 10 days after bud formation. Fruiting was visible 26.5 to 30.2 days after bud formation. Fruit setting ranged from 37.0 to 61.6% and the anthesis of male and female lowers occurred between 0600 to 0700 hours and 0700 to 0800 hours respectively. Anther dehiscence was observed after 0800 hours. Flowers were unisexual and male and female lowers were produced in the same inlorescence but female lowers were bigger. The male to female ratio was 13.4:1. Mean number of pollen per anther was 122.3 and ranged from 61.9 to 195.1. Mean pollen viability was 71.6%. Results of the breeding system showed fruit setting of 93.2, 72.2, 36.2 and 79.2% in cross pollination, self pollination, apomixis and open pollination respectively. [ABSTRACT FROM AUTHOR]

Abstract: Tropospheric ozone (O3), throughout the globe, has become a potential risk for agriculture. The present investigation was performed with two cultivars of Indian wheat (Sonalika and HUW 510) against ambient and elevated levels of O3 by using open top chambers (OTCs). Both the cultivars showed the negative impact of O3 on various growth, reproductive and yield parameters but the response among cultivars was quite distinct. Cultivar HUW 510 showed higher O3 damage in its vegetative parts (shoot and root height, leaf number, leaf area, etc.) than Sonalika, whereas the response of reproductive structures (pollen viability and viable florets per plant) was vice versa. Yield response to stress (YRS) analysis revealed that degree of damage in both cultivars was more severe under elevated concentrations of O3 over ambient. The overall results of the present study showed that in future, O3 would be a threat for wheat production but differential response among cultivars might help researchers to find out a suitable variety for an area experiencing higher concentration of O3. [Copyright &y& Elsevier]

Hybrid seed production of chili decreased in Punjab, India, despite immense demand. An experiment was conducted during 2000-01 at Vegetable Experiment Station of Punjab Agricultural University, Ludhiana, to investigate genotypic (G) and environmental (E) effects on fruit and seed setting abilities. 'MS-12' was taken as a common female line whereas '1-16', 'LLS', 'Pepsi-8-1', 'Pb. Guchhedar', `PS-4221', 'S-2529', 'S-2530' and `S-2545' were used as pollinators. Significant G x E interactions were found for all the traits measured, except pollen load per flower. Both, quantity and quality of hybrid seeds were best when crosses were made in July. July, August, and September produced greater hybrid seed yield gave a relatively high seed germination percent. [ABSTRACT FROM AUTHOR]

Study of reproductive biology and pollination ecology helps in understanding the life history patterns of species. Such a study brings to light the bottlenecks, if any, on account of which the individuals of the species are not able to reproduce in nature and ultimately helps in planning appropriate conservation strategies for the species under threat. The present study was aimed at examining the morphological and reproductive variance in Berberis lycium, a threatened ecological specialist growing within shrubberies and open hillsides of the North-Western Himalayas in India. B. lycium displays three different variants. Flowering period ranges from February to September. Pollen viability as reported on fluorescein diacetate and acetocarmine treatments was highest for variant I, while maximum pollen output was obtained for variant III. Pollen pistil interaction is brought by the movement of anther towards stigma. Fluorescence microscopy of hand pollinated club shaped stigma shows that the germinating pollen form a ring over the receptive adaxial surface. Pollination syndrome is entomophily. Variant II attracts a significantly large number of pollinators from diverse insect families. Breeding experiments reflect that plants are self-compatible and cross fertile. Reproductive output (% fruit set) was highest for variant II followed by III and I, respectively. This investigation helped to understand the effect of different biotic and abiotic constraints on the phenology and reproductive biology of the plant. The information generated so will enable conservationists to design appropriate strategies for its long-term survival and sustenance in nature. [ABSTRACT FROM AUTHOR]

• Multi-stage (seedling, vegetative and reproductive) drought tolerant rice genotypes were identified. • Multi-stage drought (MSD) affects physiological and biochemical functions of rice genotypes and stage specific responses were observed. • Physiological and biochemical basis of MSD tolerance was established in terms of PN rate, chlorophyll, protein and proline content. • Drought induced defective sugar mobilization leads to loss of pollen viability and finally grain yield. • Overall, the study provided a comprehensive understanding of multi-stage drought tolerance in rice. Under the climate change scenario, the occurrence of drought at any developmental stage of rice can cause significant yield loss in rainfed areas. Thus, the present study was conducted to explore the cumulative and stage-specific effects of drought on rice genotypes sown under field conditions. Preliminary screening of 32 rice genotypes for multi-stage drought (MSD) tolerance resulted in the identification of five promising genotypes based on yield and component traits and physiological parameters. These five promising genotypes along with checks (Sahbhagi Dhan and IR64) were grown further in a detailed study to establish their level of MSD tolerance based on physiological, biochemical and anatomical parameters. The mean grain yield of tested genotypes declined significantly (85.7%) under cumulative drought (MSD) compared to non-stress conditions. Further, MSD caused significant reduction in spikelet fertility (35.2%), test weight (16.1%), tillers m−2 (45.4%), grains panicle-1 (21.45%), flag leaf length (FLL) (13.9%), relative water content (27.3%) and membrane stability index (28.1%). Chemometric analysis also confirmed the relative MSD tolerance of promising genotypes. Photosynthetic rate (P N), stomatal conductance, total chlorophyll, protein and starch content significantly (P < 0.05) declined under MSD conditions. The contents of total chlorophyll, protein and starch were augmented from seedling to vegetative stage, and thereafter reduced at reproductive stage both under non-stress and MSD conditions. However, the level of lipid peroxidation measured in terms of thiobarbituric acid reactive substances (TBARS) and peroxidase activity increased from seedling to reproductive stage under both conditions. Among the five promising genotypes, IR84899-B-179-16-1-1-1and IR84894-143-CRA-17-1 maintained their P N rate, total chlorophyll, proline and protein contents under drought irrespective of growth stage. Moreover, drought-induced defective sugar mobilization led to the loss of pollen viability, thereby decreasing grain yield. Overall, the study established that MSD significantly affected agronomic, physiological and biochemical traits of rice plants at different developmental stages, but the tolerant genotypes sustained their yield by maintaining their efficient physiological functions and pollen viability through effective sugar mobilization. [ABSTRACT FROM AUTHOR]