Ten selected rice genotypes adapted to rainfed lowland ecosystem of Assam was evaluated for their ability to germinate and grow underwater (anoxic condition) in comparison to the aerobic condition. Anaerobic germination was allowed 10 cm water depth in pots partially filled with soils inside the net house, while Petri dishes lined with filter papers were used for aerobic germination. A general trend in reduction of germination and seedling traits were observed for all the genotypes. Three of the tolerant genotypes namely Badal, Swarna Sub 1 and Solpuna showed germination enhancement under anaerobic condition, the highest significant increase (24.3%) being registered for Badal, a cultivar adapted to semi-deep water (42-75 cm) situation indigenous to Assam followed by Swarna Sub 1 (11.6%) and Solpuna (2.1%). Both Badal and Swarna Sub 1 are tolerant to submergence at vegetative stage. Solpuna, another local cultivar adapted to the lowland ecosystem with no known submergence tolerance recorded the highest shoot length under the anoxic condition which was significantly superior to its aerobic performance. The reduction in root length was the minimum for Solpuna followed by Swarna Sub 1 and Manohar Sali. The landrace Solpuna exhibited statistically at par performance with respect to seedling length and seedling vigour index under both the environments. Seedling vigour index proved to be a reliable character for desirable improvement in rice anaerobic germination and growth. Cluster analysis grouped Solpuna separately which might be due to its unique performance under anaerobic condition. Solpuna proved its superiority over the other nine genotypes in its ability to germinate and grow under anoxic condition. The present study further indicated that AG tolerance might be independent of the submergence tolerance at the vegetative stage conferred by SUB 1A gene or gene (s) with similar effects.
We carried out the morphological, biochemical, and molecular characterization of twenty cultivars of the least studied Joha (aromatic) rice indigenous to Assam. Unweighted Neighbour Joining (UNJ) clustering based on usual Euclidean distances for thirty-seven polymorphic morphological markers grouped the cultivars into three clusters with eight, eleven, and one genotype. The Joha rice cultivars showed highly significant differences for all the quantitative traits except for panicle length. The genotypic and phenotypic coefficients of variability (GCV & PCV) were high for grain yield ha-1 (24.62 & 24.85%) and filled grains panicle-1 (23.69 & 25.02%). All the traits except days to flowering and maturity, flag leaf breadth, and spikelet fertility exhibited high heritability along with high to moderate genetic advance, indicating the predominant role of additive gene action. Mahalanobis D2 analysis revealed three multi-genotypic and four mono-genotypic clusters of the cultivars. The cultivars' average polyunsaturated fatty acids were 37.9% oleic acid, 39.22% linoleic acid, and 0.5% linolenic acid. The fatty acid profile of Local Joha was superior to the other cultivars as it showed a high level of linoleic and linolenic acid and low saturated fatty acid content. Kon Joha 4 and Ronga Joha contained the highest iron (82.88 mg kg-1) and zinc (47.39 mg kg-1), respectively, while protein content of Kon Joha-1 and amylose content of Harinarayan were the highest. Joha (Bihpuria) showed the highest gel consistency of 140.50 mm. Kalijeera, Kunkuni Joha, Kon Joha-5, Manimuni Joha and Kon Joha-2 accorded a strong aroma. PCR amplified 174 alleles with a mean value of 2.64 across the 66 polymorphic SSR markers. PIC values ranged from 0.091 to 0.698, with an average of 0.326. The highly informative (PIC>0.50) markers were RM316, RM283, RM585, RM1388, RM3562, RM171, R1M30, RM118, RM11and RM29 for identification of the twenty aromatic rice cultivars. The UNJ clustering based on Jaccard's coefficients classified the cultivars into three distinct clusters with eight, ten, and two genotypes. Our study revealed the nutritional richness of these specialty Joha rice cultivars and sufficient scope for yield enhancement through their interbreeding to keep quality intact.
The present investigation was undertaken with the objective to estimate the interrelationship of characters for seed yield in early maturing genotypes of pigeon pea (Cajanus cajan L.). The material consisted of twenty-one pigeon pea genotypes among which nineteen were early maturing genotypes received from ICRISAT (The International Crops Research Institute for the Semi-Arid Tropics), Hyderabad and two were local varieties collected from BNCA, AAU (Biswanath Chariali College of Agriculture, Assam Agricultural University), Jorhat. The experiment was conducted during kharif 2017-18 in randomized block design (RBD) with three replications at ICR farm, Assam Agricultural University, Jorhat. The estimates of genotypic correlations, in general, were found higher than the corresponding phenotypic correlation coefficients indicating strong association between two characters but the phenotypic values were lessened by the influence of environment. The seed yield per plant had shown significant positive correlation with plant height, pods per plant, pod length and harvest index both at phenotypic and genotypic level. Pods per plant and pod length had shown high positive direct effects on seed yield per plant at both genotypic and phenotypic level. At genotypic level, days to first flowering exhibited maximum positive direct effect on seed yield per plant. Pods per plant and pod length had shown high direct effects on seed yield/plant and hence direct selection for these traits may contribute towards improvement in seed yield/plant.
Uniform and healthy seeds of green gram cv. Pratap (SG-1) were treated with two mutagens, gamma rays (physical mutagen) and EMS (chemical mutagen) alone and in combination. The two hundred forty M1 progenies were laid in randomized block design with three replications during Kharif, 2017 to raise M2 generation. Analysis of variance discloses significant differences among the treatments for all the eight characters studied. It was observed that in general, the combination dose, i.e., 200 Gy+0.2% EMS gave superior results in almost all the yield attributing characteristics. High heritability coupled with high genetic advance was recorded for seed yield per plant, which indicates the predominance of additive gene action. Number of pods per plant followed by pod length showed high significant positive correlation with seed yield per plant. The character number of pods per cluster had shown positive correlation with seed yield per plant, but path analysis revealed its negative direct effect on seed yield.
The present investigation was conducted with nine genotypes in randomized block design (RBD) during Rabi, 2019-20 across the spacings viz., 60 cm x 20 cm and 50 cm x 20 cm at the ICR farm, AAU, Jorhat. In pooled analysis of variance, the genotype mean square across spacing was significant to highly significant for all the traits except ears per plant. The mean square due to genotype x spacing was significant to highly significant for the traits days to 50% silk, ears per plant, leaf area index at 60 DAS (days after sowing), leaf area index at 90 DAS, harvest index and grain moisture. Each of the hybrids responded similarly from spacing to spacing for the traits viz., days to 50% pollen shed, days to 100% dry husk, anthesis-silking interval, plant height, ear length, ear diameter, kernel rows per ear, kernels per row, 100 kernel weight and grain yield per hectare. One or more hybrids responded differently in the two spacings for the traits viz., days to 50% silk, ear height, ears per plant, chlorophyll content, leaf area index 60 DAS, leaf area index 90 DAS, harvest index, grain moisture and grain yield per plant. High heritability coupled with high genetic advance was observed for plant height, ear height, kernels per row, chlorophyll content, leaf area index at 60 DAS, leaf area index at 90 DAS, harvest index, grain yield per plant and grain yield per hectare across spacing and it indicated the preponderant role of additive gene action for these traits. Significant genetic association of both grain yield per plant and grain yield per hectare with days to 50% pollen shed, days to 50% silk, day to 100% dry husk, kernels per row, leaf area index at 60 DAS and leaf area index at 90 DAS indicated that grain yield could be improved indirectly by selecting superior plants for easily heritable traits like days to 50% pollen shed, days to 50% silk and days to 100% dry husk across spacing. Genotypic path analysis revealed that the characters viz., days to 100% dry husk, days to 50% pollen shed, ear length and kernel rows per ear had the highest positive direct effects on grain yield per plant while days to 50% silk and kernels per row had the highest negative direct effect on grain yield per plant across spacing.
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