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Open Access
Gene pyramiding for bacterial blight resistance in rice variety Uma (Mo 16)
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2016) Tintumol, Joseph; KAU; Rose Mary, Francies
Exploiting host-plant resistance through pyramiding of resistance genes have been recommended as the best approach to impart durable resistance to rice varieties in order to combat the bacterial blight (BB) disease caused by Xanthomonas oryzae pv.oryzae (Xoo). In lieu of this, F1s were produced by hybridizing the susceptible elite rice variety Uma with resistant donor parent Improved Samba Mahsuri (ISM) harbouring three R-genes xa5, xa13 and Xa21. BC1F1 individuals were generated by backcrossing the F1s using variety Uma as the recurrent parent. The present study aimed to identify the R-genes introgressed individuals in the BC1F1 population as well as to produce BC2F1s and BC1F2s of the identified R-genes introgressed BC1F1s. Foreground selection of the BC1F1 individuals was done using the R gene linked molecular markers. Restriction digestion of the PCR product of STS marker RG 556, linked to R gene xa5, with Dra1 restriction enzyme, resulted in production of alleles of size 128 bp, 514 bp, 587 bp, 624 bp, 650 bp and 836 bp in all the BC1F1 individuals as well as the parents indicating the presence of R gene xa5 in all the individuals studied. Amplification of DNA of the individuals with the functional marker xa5 SR further confirmed the presence of R gene xa5 in both the parents as well as in all the BC1F1s. Restriction digestion of the PCR product of STS marker RG 136, linked to R gene xa13, with Hinf1, produced alleles similar to that of the donor parent ISM in three BC1F1s namely, plant no. 8.3.2, plant no. 8.3.3 and plant no. 8.3.9, indicating the presence of R gene xa13 in these plants. The presence of gene xa13 in the identified BC1F1s was further affirmed by using the functional marker xa13 promoter. The analysis had resulted in the production of 560bp allele associated with the resistant allele of gene xa13 in homozygous state from donor parent ISM in the three BC1F1s mentioned above. Out of the 95 BC1F1 individuals scored with the STS marker pTA 248 linked to R gene Xa21, only BC1F1s plant no. 8.3.2, plant no. 8.3.3 and plant no. 8.3.9 were found to possess Xa 21. Results thus obtained revealed thatBC1F1plant no. 8.3.2, plant no. 8.3.3 and plant no. 8.3.9 were R gene pyramids (xa 5+xa 13+ Xa 21). Background profiling of the three R-genes introgressed BC1F1s using 22 rice microsatellite markers, revealed presence of the donor parent allele in the homozygous state. PCR analysis with the marker RM 307, however, revealed the presence of alleles from both the parents, ISM and Uma in the BC1F1 plant no. 8.3.2. This indicated that the plant was heterozygous at the marker locus and can be expected to segregate for the alleles at this locus in subsequent generations. Considering the segregation of the 22 markers the per cent recurrent parent genome recovery in the R-genes introgressed BC1F1s was estimated to be higher in BC1F1 plant no.8.3.2 but lower than the expected estimate of 75 per cent. This was also confirmed by graphical genotyping. The dendrogram thus generated out of the marker data, grouped the R-genes introgressed BC1F1s with ISM indicating that the three R-genes introgressed BC1F1s exhibited greater similarity with donor parent parent ISM at the genome level. Evaluation of BC1F1 individuals for morphological traits revealed presence of wide variability. The three R-genes introgressed BC1F1s were late in flowering compared to the recurrent parent Uma. Two of these genotypes i.e.,plant no. 8.3.2 (234 days) and plant no. 8.3.3 (228 days) flowered later than the donor parent. However, the three R-genes introgressed BC1F1s resembled the recurrent parent Uma with respect to grain and kernel characteristics. Backcrossing the three R-genes introgressed BC1F1s i.e., plant no. 8.3.2, plant no. 8.3.3 and plant no. 8.3.9 to the recurrent parent Uma resulted in 28 BC2F1s. Simultaneously, selfing of these individuals produced 850 BC1F2 seeds. Foreground and background profiling of these generations can ensure precise identification of genotypes that resembles the recurrent parent Uma possessing the resistance genes of interest with maximum recovery of recurrent parent genome.
Open Access
Evaluation of superior cultures for yield and yellow vein Mosaic resistance in okra
(Department of Plant Breeding and Genetics College of Agriculture, Vellayani, 2016) Nikitha, J; KAU; Arya, K
The present study entitled “Evaluation of superior cultures for yield and yellow vein mosaic resistance in okra (Abelmoschus esculentus (L.) Moench)” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2014-2016, with the objective to identify high yielding and yellow vein mosaic resistant cultures of okra from those evolved through inter-varietal hybridization programme. Fifteen superior cultures of okra obtained from the previous project in the Department viz., VLYA 1, VLYA 2, VLYA 3, VLYA 4, VLYA 5, VLYA 6, VLYA 7, VLYA 8, VLYA 9, VLYA 10, VLYA 11, VLYA 12, VLYA 13, VLYA 14 and VLYA 15 along with two check varieties Varsha Uphar and Kiran were evaluated in a Randomized Block Design (RBD) with three replications during summer season of 2015. The analysis of variance was calculated for the traits under study viz., days to 50 per cent flowering, number of fruits plant-1, fruit weight (g), fruit length (cm), fruit girth (g), yield plant-1 (g), plant height (cm) and duration (days) and these were found to be highly significant for all the genotypes evaluated. The maximum yield was recorded by the genotype VLYA 2 which was on par with genotypes VLYA 5, VLYA 10, VLYA 11, VLYA 13 and VLYA 15 and the minimum yield was observed by the check variety Kiran. The yield plant-1 exhibited moderate GCV (18.42%) and PCV (19.05%), high heritability (94.00%) coupled with high genetic advance (36.69%). The yield plant-1 was found to be significantly and positively correlated with number of fruits plant-1, fruit length, fruit girth, fruit weight and plant height both at genotypic and phenotypic levels. Days to 50 per cent flowering and yellow vein mosaic disease incidence was found to be negatively correlated with yield plant-1. Very high positive and significant inter-correlation was noticed between height of plant and number of fruits plant-1. The path analysis showed that number of fruits plant-1 and fruit weight showed the maximum positive direct effect towards yield. The number of fruits plant-1 had high indirect effect through fruit length. The scoring for yellow vein mosaic disease and the vulnerability index revealed that the genotypes VLYA 5, VLYA 11 and VLYA 13 were resistant to the disease during all stages of crop growth. Number of white flies was found to be highest in VLYA 10 and lowest in VLYA 2. The incidence of fruit and shoot borer was also scored and five genotypes viz., VLYA 2, VLYA 4, VLYA 11, VLYA 13 and VLYA 14 were found to be immune and VLYA 3, VLYA 5, VLYA 15 and Varsha Uphar were found to be resistant. The glass house experiment of vector transmission and graft transmission was conducted for the confirmation of disease resistance and the vulnerability index was calculated to check the severity of the disease. The genotypes VLYA 5, VLYA 11 and VLYA 13 received a score ‘0’ which indicated that these genotypes were highly resistant. Hence the genotypes which obtained a vulnerability index of ‘0’ during both field evaluation and glass house experiment were confirmed to be resistant to yellow vein mosaic disease. Hence the present study revealed that the cultures VLYA 5, VLYA 11 and VLYA 13 were having high yield and yellow vein mosaic disease resistance. So these genotypes can be used for further trials before releasing for field cultivation.
Open Access
In vitro mutagenesis and evaluation of somatic embryo derived plantlets in cassava (Manihot esculenta Crantz.)
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2016) Riya, Antony; KAU; Jiji, Joseph
The present study ‘In vitro mutagenesis and evaluation of somatic embryo derived plantlets in cassava (Manihot esculenta Crantz.)’ was conducted in the Department of Plant Breeding and Genetics, College of Horticulture during 2014-15. They study attempted to assess the variability existing among the in vitro derived plantlets of cassava genotypes Sree Jaya and CC1 as well as to generate further variability through in vitro mutagenesis. With the aim to induce variability, in vitro mutagenesis of callus derived from cassava genotypes Sree Jaya and CC1 was attempted earlier in the department. This had resulted in 10 somatic embryo derived plantlets in primary hardening stage and 58 plantlets yet to be transferred for hardening. The above plantlets formed the basic material for field evaluation undertaken in the present study. Sree Jaya and CC1 genotypes were planted as control. Out of the 58 plantlets transferred from the in vitro cultures to hardening, only 34 plantlets survived i.e., the survival was found to be 58.62 per cent. All the ten plants that were already in the primary hardening stage survived. Observations were recorded during field evaluation of the in vitro mutagen treated plants at three, six and nine months after planting as per the descriptor of cassava (Fukuda et al., 2015). The plants varied with respect to qualitative characters like colour of apical leaves, leaf retention, shape of leaf lobe, petiole colour, leaf orientation, colour of stem exterior, extend of root peduncle, shape of tuber, root colour, colour of root pulp and colour of root cortex. Variability was also observed for quantitative characters like length and width of leaf lobe, length to width ratio of leaf lobe, petiole length, distance between leaf scars, height of plant, tuber weight per plant, tuber girth, stem girth, extend of root peduncle, starch content and dry matter content. Among the mutagen treated plants of Sree Jaya none of in vitro mutagen treated plants were found to be superior with respect to tuber yield while in CC1 genotype, six plants yielded better than the control. Sensory evaluation of the tubers produced by in vitro mutagen treated plants as well as control plants was done by twelve panelists to assess consumer perception. The tubers from plant 32 (Sree Jaya; 1.2 % EMS), followed by plant 31 (Sree Jaya; 1.2 % EMS) and plant 42 (CC1; 0.9 % EMS) were most preferred for various sensory attributes evaluated. In vitro mutation being a potential method to induce variability, mutation of callus derived from genotypes was as attempted to create more variants. The callus cultures of Sree Jaya and CC1 genotypes were established as per the protocol standardised by Magaia, (2015). Friable embryogenic calli production was higher in the media MS + 8 mg L-1 2,4-D + 1 mg L-1 NAA + 0.5 mg L-1 BAP using leaf explants. Calli were subjected to physical (γ irradiation at 30- 60 Gy at an interval of 10Gy) and chemical (EMS 0.1 - 0.9 % at an interval of 0.1%) mutagens as advocated by Magaia, (2015). However, regeneration of mutagen treated friable calli was not obtained in both genotypes. Quantum of variability expressed in the in vitro mutated plants of cassava with respect quantitative traits shows the efficiency of in vitro mutagenesis in creating variability in cassava. In vitro mutagenesis is a potential tool in the hands of plant breeder to create variability especially in vegetative propagated crops. The evaluation of in vitro mutagen treated plants in the field showed wide variation with respect to most morphological as well as biometrical traits. All the plants evaluated can hence, be advanced to next generation of evaluation (M1V1) with replication to identify the mutants. From the results obtained on induction of in vitro mutation to create more variants in cassava, it is concluded that the friable callus in both the genotypes need to be cultured in alternate regeneration medium for successful regeneration of somatic embryos.
Open Access
Evaluation of cowpea [Vigna unguiculata (L.) Walp.] genotypes for yield and resistance to pulse beetle [Callosobruchus spp.]
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2017) Thouseem, N; KAU; Beena, Thomas
The present study entitled “Evaluation of cowpea [Vigna unguiculata (L.) Walp.] genotypes for yield and resistance to pulse beetle [Callosobruchus spp.]” was carried out at farmer’s field, Kayamkulam during 2015-2017, with an objective to evaluate cowpea genotypes for yield and resistance to pulse beetle. The study was conducted in two experiments. In experiment-I, yield and resistance to pulse beetle was evaluated in a Randomised Block Design (RBD) with three replications using 30 genotypes collected from different places. Experiment-II was to study the seed morphological and biochemical factors associated with resistance to pulse beetle in five relatively resistant genotypes and five relatively susceptible ones which were identified through experiment-I. The field experiment revealed that the genotype T1 (Ambalappuzha local) showed the highest mean values for days to 50 per cent flowering, length of main stem, pod weight, pod length, number of seeds pod-1, 100 seed weight and crop duration. The maximum yield plant-1 (32.91g) was obtained for the genotype T29 (Sreya) followed byT14 (Alathur local) and T7 (Dhavengarae local), whereas the minimum yield plant-1 (11.07g) was for the genotype T13 (Hridya). Thirteen genotypes were found to be infested under field condition and only very low seed damage via carry over population was noticed. The characters studied were found to be significant for all the genotypes evaluated. The pod weight exhibited the highest GCV (47.73%) and PCV (52.12%). Heritability was high for all the characters except number of primary branches plant-1, number of pods plant-1 and seed yield plant-1 which possessed moderate heritability. GA (% mean) was high for all the characters except crop duration. The association analysis revealed highly significant positive correlation for 100 seed weight, days to 50 per cent flowering, crop duration, number of seeds pod-1, pod girth, and pod length with seed yield both at genotypic and phenotypic levels. The path analysis revealed that 100 seed weight, number of pods plant-1 and number of seeds pod-1 had the maximum positive direct effect on seed yield plant-1. In no choice confinement test under experiment-I, there were significant differences among the genotypes in terms of oviposition, percentage seed damage and percentage seed weight loss. T2 (Kayamkulam local-1) had the least egg load while more eggs were laid on seeds of T29 (Sreya) and T1 (Ambalappuzha local). The highest percentage seed damage and the highest percentage weight loss were recorded for T13 (Hridya) and T27 (Bijapur local) respectively. The lowest percentage seed damage and percentage seed weight loss were observed for the genotype T7 (Dhavengarae local). In the study of seed morphological and biochemical factors associated with resistance under experiment-II, it was found that seed coat texture, seed coat colour and protein content of seeds were found to have no influence on resistance to pulse beetle. However, total phenol content of seed was having significant negative correlation with percentage seed weight loss. An index score was worked out to find out genotypes with good yield and relative resistance to pulse beetle. It was observed that the genotype T7 (Dhavengarae local) had the highest index score followed by T14 (Alathur local). The present study revealed that the genotype T7 (Dhavengarae local) was found to be a good yielder with relative resistance to pulse beetle followed by the genotype T14 (Alathur local). Hence these genotypes can be recommended for future breeding programmes.
Open Access
Genetic divergence in kiriyat (andrographis paniculata nees)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2017) Prathibha, S S; KAU; Arya, K
The study entitled “Genetic divergence in kiriyat (Andrographis paniculata Nees)." was under taken at the College of Agriculture, Vellayani during 2015-17 with the objective to assess the genetic variability present in the natural ecotypes of kiriyat from different regions and identifying the superior ecotypes in terms of herbage yield and quality. Thirty accessions of kiriyat were collected from different parts of India and were evaluated for genetic variability with respect to herbage yield (fresh weight) and quality in terms of total extractives (%). Accession A10 from Aruvipuram showed highest mean values for seedling height (15 DAT), number of primary branches, herbage yield (137.25 g), yield plant-1 (dry herbage yield plant-1) (37.79 g) and total extractives (13.6 %) followed by the A14 (Kottakkal) and A7( Kottakkunnu). The accessions A14 (Kottakkal) and A15 (Nilambur) showed highest mean values for number of secondary branches and number of leaves seedlings-1 (15 DAT) respectively. Mean value for days to 50 percent flowering was least for accession A10. The lowest yield was exhibited by A3 (Coimbatore) accession. Average duration of the plants exhibited ranged between 182.67 and 213 days. The earliest accession was A10 (Aruvipuram) with an average duration of 182.67 days. Seedling height, number of leaves seedling-1, number of secondary branches, leaf length and width, stem girth, leaf/stem ratio, plant height, herbage yield, yield plant-1 and total extractives exhibited high coefficient of variations. Heritability was high for all the characters except number of leaves seedling-1 (15 DAT), herbage yield and yield plant-1 which possessed moderate heritability. GA (% mean) was high for all the characters except plant duration. The association analysis revealed a significant correlation among almost all characters and also with yield. Path coefficient analysis revealed that plant height, herbage yield, number of primary and secondary branches had high positive direct effect on yield. The genetic divergence was studied using Mahanalobis D2 statistics and accessions were grouped into seven clusters. Cluster VII accommodated maximum number of accessions (13) followed by cluster VI (5), cluster V (4), cluster IV (3), clusters III and II (2) and cluster I (1). Highest inter cluster distance was between clusters VI and VII while intra cluster distance was highest for cluster IV. The study revealed that variability existed among the different ecotypes of kiriyat and the ecotype collected from Aruvipuram (A10) was found to be superior in terms of herbage yield and quality followed by ecotypes from Kottakkal (A14) and Kottakkunnu (A
Open Access
Evaluation of CMS based rice hybrids developed from rice varieties of Kerala identified as restorers
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2018) Nayana Jyothibas, KAU; Jayalekshmy, V G
The present study entitled “Evaluation of CMS based rice hybrids developed from rice varieties of Kerala identified as restorers” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2016-2018, with an objective to evaluate CMS based rice hybrids developed from rice varieties of Kerala as restorers, for heterosis for yield and grain quality. The study was conducted in two experiments i.e., 1) Hybrid seed production 2) Evaluation of hybrids. The first experiment, on hybrid seed production was undertaken in College of Agriculture, Vellayani during May to August, 2017 (Virippu, 2017). Two CMS lines viz., CRMS31A and CRMS32A were crossed with nine restorers. Restorers were sown in three staggers, 10 days before the sowing date of CMS lines, at the sowing date of CMS lines and 10 days after the sowing date of CMS lines. Synchronized flowering dates of the CMS and restorer lines were recorded. CRMS31A was crossed with Remya, Jayathy, Swarnaprabha, Kanakom and Neeraja. CRMS32A was crossed with Annapoorna, Aiswarya, Mattatriveni and Kanakom. Six crosses i.e., CRMS31A x Jayathi (H1), CRMS31A x Kanakom (H2), CRMS31A x Remya (H3), CRMS32A x Annapoorna (H4), CRMS32A x Kanakom (H5), CRMS32A x Mattatriveni (H6) that had given more than 1500 viable seeds were carried forward for hybrid evaluation. Date of sowing of the restorers and maintainers for getting synchronization in flowering to undertake hybridization was standardized in this experiment. In the second experiment, hybrids along with the better parent and checks were evaluated in a Randomized Block Design (RBD) with three replications during October 2017 to February 2018 (Mundakan) in IFSRS (Integrated Farming System Research Station), Karamana. Observations on 12 yield contributing traits and 8 grain quality traits were recorded in the hybrids. Genetic parameters calculated from these observations showed that the GCV and PCV values for the characters studied did not vary greatly indicating low influence of the environment in these characters. The mean performance of hybrids showed that the yield plot -1 was the highest for H5 (CRMS32A x Kanakom) followed by H3 (CRMS31A x Remya), H1 (CRMS31A x Jayathi), H2 (CRMS31A x Kanakom) and H4 (CRMS32A x Annapoorna). The hybrid H5 (CRMS32A x Kanakom) showed the highest mean values for plant height, number of filled grains panicle-1, length breadth ratio of grain and grain yield (g) plant-1. Pollen fertility of the hybrid H3 (CRMS31A x Remya) was superior to the standard check. This shows that the variety Remya is a complete restorer for male sterile cytoplasm CRMS31A. Hybrid H5 also showed pollen fertility on par with the check showing that the variety Kanakom is restorer for CRMS32A. The other hybrids H4 (CRMS32A x Annapoorna) and H6 (CRMS32A x Mattatriveni) had pollen fertility per cent around 50. So the male parents Annapoorna and Mattatriveni for CRMS32A can be considered as only partial restorers. The low level of pollen fertility was the reason for low yield of hybrids H4 (CRMS32A x Annapoorna) and H6 (CRMS32A x Mattatriveni) despite high number of productive tillers. Five out of six hybrids were red kernelled. It was found that the hybrids inherited the kernel colour from the male parents. The kernel length by breadth ratio of all the hybrids was significantly higher than that of Uma. The hybrids had a medium to slender grain shape (kernel length by breadth ratio 2.1 to 3 and above). This may be the reason behind the phenomenon of curling noted in cooked rice in all the rice hybrids studied. Standard heterosis for yield plot-1of the hybrids calculated over the standard check variety Uma was the highest for H5 (CRMS32A x Kanakom) followed by H3 (CRMS31A x Remya) and H1 (CRMS31A x Jayathi). Heterobeltiosis for yield calculated over the better parent was maximum for H1 (CRMS31A x Jayathi) followed by H5 (CRMS32A x Kanakom). Amylose content of most of the hybrids fell into intermediate category along with that of the check variety Uma, showing the hard and non sticky nature of the cooked rice of the hybrids. Cooking time for hybrids was less compared to that of Uma (29 minutes). This evaluation of hybrids could identify two promising hybrids for Kerala H5 (CRMS32A x Kanakom) and H3 (CRMS31A x Remya) which could give a yield advantage of 17.91% and 16.37% over the popular rice variety Uma. These two hybrids had long slender grain shape with red kernel colour. The amylose content of these two hybrids was also intermediate and low. These hybrids had a lower cooking time and good head rice recovery. Hence the hybrids can be recommended for Kerala after trials over locations and seasons. A better seed production technique has to be standardized before commercial release.
Open Access
Identification of water stress tolerant amaranthus genotypes (Amaranthus tricolor L.) with high yield and quality
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2018) Shahiba, A M; KAU; Beena Thomas
The present study entitled “Identification of water stress tolerant amaranthus genotypes (Amaranthus tricolor L.) with high yield and quality” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2016-2018, with an objective to identify high yielding genotypes of amaranthus with good quality and tolerance to water stress. The study was conducted under two experiments. In the first experiment thirty accessions of Amaranthus tricolor L. available in the Department of Plant Breeding and Genetics and collected from other sources were evaluated for yield under field condition and morphologically described using IBPGR descriptor for the amaranthus. Madhur local (A22) recorded highest yield plant-1(125.926g) followed by Kalliyoor local (A4), Ayyanthole local (A28), Haripad local (A7), Palakkadu local (A2), Anachal local (A6), Aryanadu local (A21), Poonkulam local (A20), Kazhakkuttom local (A9) and Kannara local (A29). In the second experiment, these ten genotypes selected based on the yield were evaluated in a Randomized Block Design (RBD) with three replications during November 2017- December 2017. Water stress was imposed after 5 days of irrigation to water holding capacity to the transplanted seedlings by scheduling the irrigation at a depth of 20mm at 20mm CPE (Cumulative Pan Evaporation). Analysis of variance was calculated for all the characters under study and was found to be significant for all the genotypes evaluated. The mean performance of the genotypes for the characters were studied. The maximum yield was observed for the genotype A22 (Madhur local) followed by the genotype A9 (Kazhakkuttom local), genotype A20 (Poonkulam local) and genotype A2 (Palakkadu local) and the minimum yield was recorded for genotype A4 (Kalliyoor local). The genotype A22 (Madhur local) showed the highest mean values for stem girth, number of branches, length of leaf lamina, leaf to stem ratio, membrane integrity, relative water content, proline content of leaves, vitamin A and lowest oxalate content. The character Vitamin A content registered the highest GCV (41.22%) and PCV (41.25%). High heritability coupled with high genetic advance was observed for leaf width, number of branches, yield plant-1, protein content, fibre content and vitamin A. The yield plant-1was found to be significantly and positively correlated with leaf width, number of branches, yield plot-1, membrane integrity, proline content of leaves and vitamin A both at genotypic and phenotypic levels. Petiole length and percentage leachate were found to be negatively correlated with yield plant-1. Path analysis revealed that number of branches, yield plot-1and proline content of leaves had the maximum positive direct effect on yield plant-1. The results of the present study showed that genotype A22 (Madhur local) was superior in yield performance under water stress condition followed by the genotype A9 (Kazhakkuttom local), genotype A20 (Poonkulam local) and the genotype A2 (Palakkadu local). The genotype A22 (Madhur local) also recorded the maximum stem girth, number of branches, length of leaf lamina, leaf to stem ratio, membrane integrity, relative water content and proline content of leaves with high Vitamin A and low oxalate content. Presence of proline in the leaves might be considered as an important water stress tolerance mechanism.
Open Access
Identification of saline tolerant rice hybrids for pokkali tract
(Department of Plant Breeding and Genetics, Vellanikkara, 2018) Nikhil Narayanan; Biju, S
Various abiotic stresses causing a decline in global rice production are drought, salinity and chillness. Among these, salinity is the major factor that affects crop productivity. The traditional rice varieties grown under Pokkali area show remarkable tolerance to salinity and floods making it unique. However, the yield potential of these varieties is low. In India, out of ninety three rice hybrids developed, a few viz. DRRH 28, KRH 4, PSD 3, etc. were reported to have tolerance to salinity. Considering the potentials of hybrids, identification of salt tolerant hybrids suitable for Pokkali tract of Kerala is an urgent need of the hour. Hence, the study was designed to explore the adaptability of eight rice hybrids to the unique tract of Pokkali and evaluation of traits associated with salinity tolerance. The study comprised of two experiments, the first experiment was Laboratory screening for salinity tolerance and the second experiment was Field evaluation of rice hybrids in Pokkali tract. The laboratory screening was done following a completely randomised design and the genotypes were grown in Yoshida's solution and evaluated for various seedling characters. High shoot length, root length, high root CEC and high root and shoot proline content were seen in Vytilla-6 followed by Ezhome-2. Low root and shoot proline content were observed in IR-29 confirming its susceptibility to salinity. Among the hybrids, a high value for shoot length, root length, total number of roots, root CEC, root proline, shoot proline and survival per cent was observed in the hybrids CORH-3 and KRH-4. Vigour index was high in Sahyadri 4 followed by KRH-4 and low in MRP- 5401. Vytilla-6 and Ezhome-2 showed the high survival per cent while low survival per cent was noticed in Sahyadri 2 and MRP-5401. Vytilla-6 exhibited high chlorophyll content and RWC while low RWC was recorded in MRP-5401, Sahyadri- 2 and Sahyadri-4. Ca in root and shoot along with Na content in shoot were high in IR-29 while Vytilla-6 had low Ca and Na content. High Na in root was seen in Sahyadri 4 followed by Sahyadri 3. High amount of root Cl2 was recorded in Sahyadri-3, Sahyadri-1, Sahyadri-4, IR-29 and Sahyadri-2 while, the lowest amount of root and shoot Cl2 was in Vytilla-6. High amount of shoot Cl2 was seen in Ezhome-2 and IR-29. High amount of root and shoot SO4 content was seen in IR-29, Sahyadri-3, Sahyadri-4, Sahyadri-2 and Sahyadri-1. The lowest root and shoot SO4 content was recorded in Ezhome-2, followed by Vytilla-6. Low visual score of 3 was recorded in Vytilla-6 and Ezhome-2; a score of 5 was recorded for CORH-3, MRP-5401, TNAU RH-4 and KRH-4. Sahyadri-2, Sahyadri-3 and Sahyadri-4 were observed to have scored more than seven. Score 9 was noticed in Sahyadri-1 and IR-29, indicating that these genotypes are more susceptible to salinity. Visual score under salinity was found to be negatively correlated with shoot and root length, number of roots, vigour, proline content and RWC, while it was positively correlated with content of Ca, Na, Cl2, SO4 and K in the plant tissue. Field evaluation of rice hybrids in Pokkali tract was done during Kharif season of 2016-17, following a randomised block design. Days to fifty per cent flowering and maturity showed that all hybrids became early under salinity. Tall plants were observed in Vyttila-6 and Ezhome-2 and short plants in IR-29. High number of productive tillers was observed in CORH-3 and low in Sahyadri-2. Ezhome-2, IR-29 and Vyttila-6 had high number of spikelets per panicle while seed setting percentage and long panicles were observed in Ezhome-2. Spikelet sterility was high in Sahyadri-2 and low Ezhome-2. High 1000 grain weight was observed in Ezhome-2 and low in IR-29. Based on visual scoring Vyttila-6 was classified as highly tolerant and IR-29 as highly susceptible. Correlation studies indicated that grain yield per plant was positively correlated with productive tillers per plant and seed setting per cent, while it was found to be negatively correlated with sterility per cent. Visual scoring was negatively correlated with plant height, uppermost internodal length, days to maturity and seed setting per cent. The hybrid CORH-3 was found to be moderately tolerant based on visual scoring and it produced highest yield per plant indicating that this hybrid is better than saline tolerant traditional varieties.
Open Access
Breeding cowpea (Vigna unguiculata (L.) Walp.) for resistance to spotted pod borer (Maruca vitrata Fab.)
(Department of Plant Breeding and Genetics, Vellanikkara, 2018) Ambavane Ajinkya Rajendra; KAU; Jiji Joseph
Cowpea [Vigna unguiculata (L.) Walp.] is important pulse crop rich in nutrients, especially proteins. This crop is cultivated in the tropics of Asia, Africa and other parts of the world. Nevertheless, the production of cowpea is unable to achieve its summit. One of the prime reasons for this is the infestation of a notorious pest, the spotted pod borer, (Maruca vitrata Fab.; Lepidoptera: Crambidae). Spotted pod borer is one of the most important post-flowering pests of cowpea in the tropics. It is a major lepidopteran pest and damage cause to cowpea by the pest almost always crosses economic threshold level. Hence, the present investigation was conducted in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, Kerala Agricultural University, Thrissur during 2015 to 2018 with the objective of identification and incorporation of resistance against spotted pod borer in high yielding varieties of cowpea and assessment of parental polymorphism at the molecular level Thirty genotypes of cowpea formed the material for the study. These genotypes were subjected to field screening against spotted pod borer. These genotypes were also evaluated for morphological and biochemical basis of resistance. Five selected genotypes from experiment 1 then hybridised with four high yielding genotypes viz., Geethika, Vellayani Jyothika, Lola and Kashi Kanchan following Line × Tester mating design. Twenty F 1 hybrids evaluated for field resistance and the morphological basis of resistance. Progenies of selected F 1 hybrids grown as F 2 populations and evaluated for same parameters as like F 1 s. Thirty genotypes were also subjected to molecular screening by 40 SSR primers. Wide variation was observed in terms of different damage parameters. Ten genotypes viz., Hridya, Palakkadan thandan payar, EC 300039, EC 98668, EC 101216, IC 52110, IC 39945, IC 2918, IC 39922 and IC 39916 recorded total damage below five per cent. Among them, IC 39922 observed to have no flower bud and flower damage, EC 300039, EC 98668, IC 52110, IC 39945, IC 2918 and IC 39916 recorded no flower damage, whereas, Palakkadan thandan payar, IC 39945, IC 2918 and IC 39947 were free from pod damage. The highest damage was recorded in the variety Bhagyalakshmy (48.46 %) followed by variety Lola (30.04 %). Analysis of the morphological basis of resistance to spotted pod borer revealed the negative correlation of trichome density and length on flower bud, trichome density on the pod and pod wall thickness with respective damage parameters. With respect to the biochemical basis of resistance to spotted pod borer, total sugar content, reducing sugar content and non-reducing sugar content of flower bud and pod showed a positive correlation with damage parameters, but the correlation was not significant. However, the total protein content of pod showed a strong and positive correlation with pod damage. Total phenol content of flower bud showed strong negative correlation with damage parameters. Polyphenol oxidase activity in flower bud and pod exhibited a strong negative correlation with damage parameters. The crude fibre content of pod also showed a strong negative correlation with pod damage. In experiment 3, three SSR primers viz., CLM0061, CLM0295 and CLM0300 recorded high polymorphic information content (0.70, 0.71 and 0.76, respectively). Primer CLM0190 observed to have high amplicon size (307.03-415.73 bp). Jaccard’s similarity coefficient was highest between IC 52118 and IC 39916 (0.643) and was lowest between Kashi Kanchan and TVX-944 (0.022). Cluster analysis of SSR data grouped 30 genotypes in 22 clusters, and the 21 st cluster was observed to have more members (3 genotypes). Most resistant genotype, IC 2918, grouped in a separate cluster which proved its diverse nature from other genotypes. Principal component analysis of SSR data placed three yard-long bean genotypes viz., Geethika, Vellayani Jyothika and Lola near to each other in a two-dimensional score plot. The same analysis also formed two clusters with more number of genotypes which placed resistant and susceptible genotypes separately. In field screening of F 1 hybrids, Hybrid 20 observed to have total damage below 5 per cent. Eight hybrids recorded total damage in the range of 5 to 10 per cent. These hybrids were selected for next experiment. Line × Tester analysis of F 1 s revealed Kashi Kanchan, EC 98668 and IC 2918 as a good combiner for resistance against spotted pod borer. Hybrid 5, Hybrid 6, Hybrid 10, Hybrid 11, Hybrid 13, Hybrid 15, Hybrid 16, Hybrid 17, Hybrid 18, Hybrid 19 and Hybrid 20 observed to have desired negative heterosis (mid-parent) for total damage. In F 2 plant screening, Hybrid 1 population recorded low mean for total damage (6.76 %), whereas, the population of Hybrid 3 recorded high mean (12.17 %). Around 100 plants of F 2 generation recorded total damage below ten per cent. Out of them, around 38 plants also registered good yield. These plants should be further evaluated to isolate high yielding resistant segregants.

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