Characterization of Multiple Grain Rice (Oryza sativa L.) Biramsundari from Bangladesh

Biramsundari is a rice germplasm from Bangladesh showing one to four grain in a single seed. Comparative study of morphological traits revealed that BS is a taller rice variety compared to modern rice varieties with longer and wider flag leaves, longer panicle length and higher thousand seed weight (TSW) than transplanted aman rice variety BRRI dhan 49. Flower morphological analysis unveil that multiple grains of Biramsundari are originating from multiple number of carpels in each floret. About 40.1% flower contains three carpels. Fluorescent microscopic study also confirms the zygotic origin of multiple grain formation in Biramsundari. Molecular characterisation of Biramsundari was performed by using TeaCpSSR27 and TeaCpSSR28 chloroplast microsatellite markers. The results of this investigation reveal that atpF and rsp14-psaB intergenic spacer regions of Biramsundari have variation compared to sequences of with O. sativa ssp. indica, O. sativa ssp. japonica and O. rufipogon. Plant Tissue Cult. & Biotech. 31(2): 115-122, 2021 (December)

Effects of the Harvest Stage of Maize Hybrids on the Chemical Composition of Plant Fractions: An Analysis of the Different Types of Silage

The chemical composition of plant components of three maize hybrids harvested at the beginning of six reproductive stages of maturity was compared. The hybrids evaluated included Maximus VIP3, Defender VIP and Feroz VIP, which were evaluated at each of following stages: R1 (grain formation), R2 (milky grain), R3 (pasty grain), R4 (floury grain), R5 (hard grain) and R6 (ripe grain). The advancement in maturation was linearly related to the crude protein (CP) content of the stem, whole plant, and leaves, and there was a difference among the hybrids. Between R4 and R5 stages, Maximus and Defender presented the highest CP contents for husk (6.58 and 5.42% for Maximus; 5.54 and 5.17% for Defender). The neutral detergent fiber (NDF) of the leaves showed a quadratic relationship with the advancement of maturation but did not differ among the hybrids. For all the hybrids, the NDF content in the husk and cobs increased linearly during the reproductive stages (>77 and 78%, respectively, for the three hybrids in R6). Defender had the lowest NDF content of the cob in R3. The acid detergent lignin contents did not differ among stages in the stems, and showed a linear decrease throughout the whole plant, though the contents did not differ among the hybrids. Due to the differences observed, recommendations for harvest based on the maturity stage for each hybrid should be taken into consideration. There seems to be no important distinction among hybrids for harvesting and use of straw. Despite the reduction in grain yield, an early harvest for earlage or snaplage can provide lower lignin content in husk and cob, as well as higher protein content in the husk, favoring the nutritional value of the vegetative fraction (husk and/or cob).

Numerical Analysis of Solidification Behavior during Laser Welding Nickel-based Single-crystal Superalloy Part IV: Optimization of Thermo-metallurgical Factors

Important metallurgical factors, such as alloying aluminum redistribution, supersaturation and undercooling of dendrite tip around solid/liquid interface, are separately optimized to alleviate stray grain formation and columnar/equiaxed transition (CET) with series of welding conditions and provide a very efficient method for microstructure control through modification of growth kinetics of dendrite tip under nonequilibrium solidification conditions of ternary Ni-Cr-Al molten pool. Asymmetrical (001)/[110] welding configuration is inferior to symmetrical (001)/[100] welding configuration, because overall area-weighted alloying redistribution, supersaturation and undercooling of dendrite tip throughout the solid/liquid interface of weld pool are consistently severer to exacerbate solidification behavior and microstructure development and incur morphology instability of columnar/equiaxed transition. High heat input, such as combination of higher laser power and slower welding speed, monotonically increases aluminum enrichment, supersaturation and undercooling of dendrite tip near solidification interface to simultaneously deteriorate nucleation and growth of stray grain formation and weaken columnar dendrite morphology, while low heat input, such as combination of lower laser power and faster welding speed, decreases solute buildup, relieves supersaturation and beneficially suppresses dendrite tip undercooling to minimize equiaxed dendrite morphology in the crack-susceptible region, and thereby facilitate single-crystal epitaxial growth with decrease of thermo-metallurgical factors for columnar/equiaxed transition in order to provide prerequisite for optimization of welding conditions. Favorable solidification conditions are obtainable with preferential crystallographic orientation to eliminate columnar/equiaxed transition under which the epitaxy of single-crystal metallurgical properties across fusion boundary of substrate is predominantly promoted to essentially reduce stray grain formation in (001)/[100] welding configuration, and is kinetically capable of significant reduction of microstructure anomalies and nonuniform solidification behavior. The useful relationship among welding conditions, alloying aluminum redistribution, supersaturation and undercooling of dendrite tip is properly established within dendrite stability range through thorough analysis. In addition, the validation of theoretical predictions is fairly reasonable by the experiment results. It is worth that the contributions of kinetics-related solidification phenomena with advancement of solid/liquid interface are imposed altogether to understand why stray grain formation occurs on the basis of controlling mechanism of minimum undercooling or minimum velocity by the reproducible methodology procedure.

Numerical Analysis of Solidification Behavior during Laser Welding Nickel-based Single-crystal Superalloy Part III: Auspicious Control of Dendrite Tip Undercooling

Location-dependent dendrite tip undercooling is numerically elucidated to predict crystallography-assisted resistance to centerline grain boundary formation and morphology transition of stray grain formation ahead of dendrite tip in the ternary Nickel-Chromium-Aluminum molten pool during course of nonequilibrium solidification for explanation arduous solidification behavior control of microstructure melioration. Heat input is not so salient as welding configuration for auspicious solidification behavior and beneficial microstructure development. Advantageous symmetry of welding configuration efficiently lessens dendrite tip undercooling for prevalent dendrite morphology stability of planar interface with alleviation of columnar/equiaxed transition (CET) phenomenon. The bimodal distribution of undercooling ahead of dendrite tip is symmetrically dominant for (001)/[100] growth crystallography with capability of increasing morphology of interface kinetics for epitaxial growth and guarantees single-crystal potential. Alternatively, the distribution of undercooling ahead of dendrite tip is asymmetrically prevalent for (001)/[110] growth crystallography with inefficiency of nonhomologous solidification behavior for discontinuous intersection of solidification interface. Undercooling ahead of dendrite tip inside [010] growth region is not so wide as inside [100] growth region, where thermometallurgically initiates unstable solidification interface and inferior solidification behavior, with unfavorable crystallography in the case of asymmetrical (001)/[110] welding configuration. The smaller heat input is applied, the narrower undercooling ahead of dendrite tip is acquired to significantly mitigate microstructure anomalies with favorable solidification conditions, meliorate metallurgical properties and potentially improve weldability with viability of epitaxial columnar morphology and vice versa. Optimum heat input, especially low laser power and high welding speed together, is a viable and robust way to limit plethora of undercooling and easily decrease solidification behavior anomalies. When low laser power or rapid welding speed is chosen, low heat input not only lessens [100] dendrite growth region, where is spontaneously vulnerable to columnar/equiaxed transition, as ramification of prominent dendrite tip undercooling, but also metallurgically ameliorates [001] dendrite growth region, where morphologically aids epitaxial growth and activates stable planar interface, with achievable diminution of dendrite tip undercooling. Symmetrical (001)/[100] welding configuration, in which undercooling ahead of dendrite tip is preferably narrower than asymmetrical (001)/[110] welding configuration, is one of the most important ingredient for auspicious control of dendrite tip undercooling, once other welding conditions are similar. The main reason, why welding conditions (both low heat input and (001)/[100] welding configuration) is quite superior to welding conditions (both high heat input and (001)/[110] welding configuration), is attributable to favorable crystallography-dependent thermometallurgical factors to suppress inhomogeneous microstructure as long as solidification conditions within marginal stability range. Satisfying crack-free microstructure development is strongly interdependent on kinetics-related solidification behavior through scrupulous control of dendrite tip undercooling to balance between microstructure amelioration and weld depth requirement. The mechanism of columnar/equiaxed transition elimination, by which kinetic driving forces of abnormal microstructure development within high-undercooling region on either left or right side of weld pool is diminished through challenging method of crystallography-dependent dendrite tip undercooling control, is therefore proposed. Finally, there is reasonable consensus between numerical analysis results and experiment results. The numerical analysis provides credible insight into where is liable to microstructure anomalies and why dendrite tip undercooling suppresses stray grain formation for successful laser surface modification of Ni-based single-crystal superalloy.