​Identification of Low Light Tolerant Blackgram Varieties with Respect to Morpho-physiology and Yield

Background: Blackgram is generally considered as a shade sensitive crop. Nevertheless, it fits well in intercropping, crop rotation and crop mixture in coconut gardens thus forming an integral part of cropping systems of the tropics. To encourage and extend blackgram cultivation in coconut gardens, suitable varieties tolerant to shade, need to be identified. The current study aims to screen shade tolerant blackgram varieties with respect to morpho-physiological characters and yield. Methods: Field experiment was conducted during Rabi 2019 at College of Agriculture, Vellayani, Kerala, India. Uniformly spaced coconut palms of age above 40 years were selected having a light intensity of 40-46.5 Klux. Twelve promising blackgram varieties along with three cultures were evaluated under low light intensity in coconut garden. Morpho-physiological attributes and yields were recorded and analysed statistically. Result: Superior growth attributes and physiological parameters like stomatal frequency, chlorophyll content, photosynthetic rate and transpiration rate were recorded in varieties namely, DBGV 5, Sumanjana and VBN 5. These varieties were found tolerant to low light intensity with DBGV 5 recording significantly higher yield (1183.33 kg ha-1) followed by VBN 5 (916.67 kg ha-1) and Sumanjana (906.67 kg ha-1) and could be recommended as suitable for intercropping in coconut garden.

Leaf epidermal anatomy of Cynodon dactylon (L.) Pers. in relation to ecotypic adaptation

Qualitative and quantitative studies were done on leaf epidermal characteristics with special reference to stomatal features to find out the impact of environmental condition on twenty four accessions of Cynodon dactylon (L.) Pers. collected from different ecological habitats of Bangladesh. The foliar epidermal peels from both surfaces of mature leaves were observed under microscope. The leaves were found to be amphistomatic and stomata were paracytic type. The epidermal cells in this study were found to be sinuous. Silica bodies were found to be saddle and cross shaped. Prickles angular were pointed at the tip. Macro-hairs were present in all the accessions, but no micro-hair was found both adaxially or abaxially. Stomatal frequency and stomatal index were found to vary from accession to accession on both adaxial and abaxial surface of leaves, and the differences were statistically significant in most of the cases. Bangladesh J. Plant Taxon. 28(1): 171-193, 2021 (June)

The Morpho-Genetic Estimation of Drought Stress in Sunflower Seedlings under Laboratory Conditions

Drought stress directly affects the growth along with productivity of plants by altering plant water status. The present study was carried out to characterize the genetic variability for seedling and morpho-physiological parameters in different sunflower genotypes under water stressed conditions. A total twenty seven genotypes including two hybrids, eight advanced lines and seventeen accessions of sunflower (Helianthus annuus L.) were tested against drought stress at seedling stages by applying Polyethylene glycol (PEG). Significant means were calculated among traits using analysis of variance (ANOVA) whereas, correlation and principle component analysis also confirmed that germination percentage, root length, shoot length, chlorophyll content, stomatal frequency are positively linked with each other hence, these traits were responsible for most of variation among genotypes. The cluster analysis showed that genotypes Ausun, line-1, line-2, line-3, 17578, 17570, line-6, line-7 and 17562 are more diverse among all the genotypes.

Salt Tolerance in the Halophyte Suaeda maritima L. Dum.—the Effect of Oxygen Supply and Culture Medium on Growth

Suaeda maritima is an annual species that grows in salt marshes and tolerates not only salt but also flooding, although plants are smaller at lower than at higher elevations of salt marshes. We investigated whether adventitious roots play a role in tolerance to flooding and how flooding affects ion accumulation in the shoots, a determinant of growth in this species. We examined the response of plants grown in Stout and Arnon culture solution to different periods of flooding at different salinities and verified our results with plants grown in other culture solutions (Hoagland and Yoshida). We measured growth, photosynthesis and estimated stomatal frequency as well as the accumulation of Na+, Ca2+, Mg2+ and K+: plants grew and photosynthesised optimally in 200-mM Na+ (in Stout and Arnon solution), but the optimal concentration for growth increased to 450 mM when in Yoshida solution. Flooding always decreased growth, but had little effect on Na+ concentrations. Although plants produced adventitious roots, their mass decreased rather than increased with flooding. The decrease in production of adventitious roots under flooded conditions suggested that they were not important in the tolerance of this species to submergence—an unusual response compared with the general response of flooding-tolerant plants.

Colchicine-induced chromosome doubling in Pennisetum interspecific hybrids and its effect on plant morphology

We report the production of hexaploid plants of interspecific hybrids of Pennisetum, with the ultimate aim to improve the biomass yield, drought tolerance and multicut behaviour of this genus. Chromosome doubling was achieved with the application of colchicine at three different concentrations (0.05, 0.1 and 0.2%) for two time durations (12 and 24 hours). The root slips and stem cuttings of interspecific hybrids were used for treatment and the root slips were found to be more efficient. The preliminary screening to select the putative hexaploid plant was done based on stomatal frequency and morphology. Plants containing significantly lower stomatal frequency and larger stomata size were selected for further analysis by chromosome counting. This experiment confirmed that 0.1% concentration of colchicine treatment to root slips for 24 hours was more effective to induce the amphiploids in Pennisetum.

Stomatal frequency of Quercus glauca from three material sources shows the same inverse response to atmospheric pCO2

Background and AimsThe inverse correlation between atmospheric CO2 partial pressure (pCO2) and stomatal frequency in many plants has been widely used to estimate palaeo-CO2 levels. However, apparent discrepancies exist among the obtained estimates. This study attempts to find a potential proxy for palaeo-CO2 concentrations by analysing the stomatal frequency of Quercus glauca (section Cyclobalanopsis, Fagaceae), a dominant species in East Asian sub-tropical forests with abundant fossil relatives.MethodsStomatal frequencies of Q. glauca from three material sources were analysed: seedlings grown in four climatic chambers with elevated CO2 ranging from 400 to 1300 ppm; extant samples collected from 14 field sites at altitudes ranging from 142 to 1555 m; and 18 herbarium specimens collected between 1930 and 2011. Stomatal frequency–pCO2 correlations were determined using samples from these three sources.Key ResultsAn inverse correlation between stomatal frequency and pCO2 was found for Q. glauca through cross-validation of the three material sources. The combined calibration curves integrating data of extant altitudinal samples and historical herbarium specimens improved the reliability and accuracy of the curves. However, materials in the climatic chambers exhibited a weak response and relatively high stomatal frequency possibly due to insufficient treatment time.ConclusionsA new inverse stomatal frequency–pCO2 correlation for Q. glauca was determined using samples from three sources. These three material types show the same response, indicating that Q. glauca is sensitive to atmospheric pCO2 and is an ideal proxy for palaeo-CO2 levels. Quercus glauca is a nearest living relative (NLR) of section Cyclobalanopsis fossils, which are widely distributed in the strata of East Asia ranging from the Eocene to Pliocene, thereby providing excellent materials to reconstruct the atmospheric CO2 concentration history of the Cenozoic. Quercus glauca will add to the variety of proxies that can be widely used in addition to Ginkgo and Metasequoia.

Taxonomic significance of stomatal complex in fifteen species of Dendrobium Swartz (Orchidaceae) of Nepal

Dendrobium Swartz is one of the largest and most problematic genus of the tribe Dendrobieae of the family Orchidaceae. Nepal harbors about thirty-one species of Dendrobium. Micro morphological characters like the stomatal complex in fifteen species of DendrobiumSwartz (Orchidaceae) of Nepal were studied for understanding the taxonomic significance of stomatal complex within the genus. For the study of stomatal complex of leaf, Carpenter’smethod was followed. Stomatal index and stomatal frequency were calculated using formulagiven by Salisbury. The terminologies used for the stomatal complex type were followed those of Patel. In all species the leaf surface was found hypostamic. Tetracytic (a-tetra-monocyclic,b-tetra-monocyclic and c-tetra-monocyclic) and eupara twi-monocyclic with hexa-monocyclictypes of stomata were recorded in the genus. Tetracytic type was found in fourteen species and eupara twi-monocyclic with hexa-monocyclic was found in only one species. The elliptical shape of stomata was found in more species than the circular shape. The epidermal cells of leaf was found rectangular, square, polygonal to irregular. The distribution of stomata on leaf surface, type of stomata and shape of epidermal cells were found to be taxonomically significant. These characters could be used as distinguishing characters to delimit the species in the genus.