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Kerala Agricultural University, Thrissur
The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively.
Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively.
On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs.
In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc.
During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU).
Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.
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ThesisItem Open Access Physiological biochemical and molecular studies in medicinal rice (Oryza sativa L.) Njavara as influenced by abiotic stresses(Department of Plant Physiology, College of Agriculture, Vellayani, 2020) Wagh Yogesh, Sahebrao; KAU; Viji, M MThe study entitled “Physiological, biochemical and molecular studies in medicinal rice (Oryza sativa L.), Njavara, as influenced by abiotic stresses” was conducted during 2015 to 2019 at the Department of Plant Physiology, College of Agriculture, Vellayani, Thiruvananthapuram. The objective of the study was to elicit information on the physiological, biochemical and molecular attributes associated to secondary metabolites accumulation due to abiotic stresses viz., shade, drought and UV-B stress in medicinal rice Njavara. The study was conducted as three different experiments with black glumed and yellow glumed njavara. Experiment one was a pot culture study laid out in Completely Randomized Design (CRD) with two varieties and five treatments. The study included a combination of two levels of shade stress and two levels of water deficit stress and a control with four replications and with three pots in each replication. The observations were taken at different critical stages of the crop viz., vegetative stage, panicle initiation stage, flowering stage and harvesting stage. The results revealed that the morphological characters such as plant height, leaf area index and specific leaf area were higher under 40% shade whereas under 50% field capacity, they were found to be highly reduced. Number of tillers per plant was higher under control (T5) compared to shaded and water deficit conditions. Leaf gas exchange parameters viz., photosynthetic rate, stomatal conductance and transpiration rate were lesser under both experimental conditions compared to the control. However maximum reduction of leaf gas exchange parameters were recorded at 50% field capacity (T3) followed by 40% shaded condition (T2) compared to the control (T5). Among the biochemical characters, maximum chlorophyll content was found under 40% shaded condition (T2). The biochemical parameters such as flavonoid, phenol and proline content of leaves were found higher under 50% field capacity (T3) at all the growth stages studied. The total flavonoid content in the grains was found higher under 75% field capacity (T4) followed by 20% shade treatment (T1) in both the varieties. The second experiment was carried out in pot culture in CRD with four treatments, three replications and four pots per replication. The crop was subjected to UV-B (280-320 nm) radiation with the help of UV-B fluorescent tubes during the different critical stages of plants i.e. from vegetative stage, from panicle initiation stage and from flowering stage till harvesting in ventilated polyhouse. The UV-B tubes were switched on for 4 hours daily from 10 am to 2 pm and the average intensity of UV-B radiation at the canopy level of plants was maintained at 4 Wm-2. The control was maintained in another compartment of polyhouse without UV-B tubes. The results indicated that the morphological characters viz., plant height, leaf area index, specific leaf area and tiller number reduced significantly under UV-B radiation treatment and the maximum reduction was observed in treatment T1 (UV-B treatment from vegetative stage). Leaf gas exchange parameters as well as chlorophyll content decreased significantly under UV-B radiation treatments compared to the treatment without UV-B radiation. However flavonoid, phenol and proline contents of leaves were found to increase under UV-B treatments (T1, T2 and T3). The accumulation of total flavonoid in grains was found significantly higher in treatment T2 (UV-B radiation treatment given from panicle initiation stage) in both the varieties. The treatments which resulted in the highest accumulation of flavonoid content in grains were selected from experiment 1 (20% shade and 75% field capacity) and experiment 2 (UV-B radiation treatment from panicle initiation stage) for molecular analysis in experiment 3. Protein profiling was done in leaves using SDS-PAGE in which, there was variation in the intensity of large subunit (55 kDa) as well as small subunit (16 kDa) of RuBisCO, between the varieties and the treatments. The intensity of those bands were found higher in 20% shade (T1), 75% field capacity (T2) and control (T4) whereas under UV-B radiation treatment from panicle initiation stage (T3) relatively lesser intensity was exhibited. Gene expression study in grains using qRT-PCR revealed relatively higher expression of chalcone synthase (CHS) and CYP75B4 genes in black glumed njavara (V1) than the yellow glumed njavara (V2) variety. Also the gene expression study revealed that both the genes were over expressed under T3 (UV-B radiation treatment from panicle initiation stage) and T2 (75% field capacity). But both the genes (CHS and CYP75B4) were found down regulated under T1 (20% shade) condition. The present study revealed that the flavonoid content in grains is higher in black njavara (V1) compared to yellow njavara (V2). The study also indicated that the various parameters studied viz., growth, physiological and biochemical were found to have positive influence on the flavonoid accumulation of grains. But the chlorophyll content was found to have negative influence on the flavonoid content of grains. Proline content was less in black njavara (V1) under UV-B radiation compared to yellow njavara (V2). Based on the present study it is concluded that the black glumed njavara performed better than yellow glumed njavara under all the stress conditions studied and can be exploited better for its therapeutic value. Application of mild stress levels viz., water deficit (75% field capacity) or UV-B radiation treatment from panicle initiation stage may be utilized to enhance the medicinal quality of this crop.ThesisItem Open Access Identification of molecular markers and quantitative trait loci(QTLs)associated with drought tolerant and plant production traits in rice(Oryza sativa L.)using association genetic analysis(Department Of Plant physiology, College Of Agriculture, Vellayani, 2020) Nithya, N; KAU; Beena, RThe present investigation entitled “Identification of molecular markers and Quantitative Trait Loci (QTLs) associated with drought tolerant and plant production traits in rice (Oryza sativa L.) using association genetic analysis” was conducted at Department of Plant Physiology, College of Agriculture, Vellayani and RARS, Pattambi during 2016-18 . The objective of the study was to identify molecular markers, Quantitative trait loci (QTLs) associated with drought tolerance and plant production traits in rice under drought condition. The extend of variation for water stress indicators for morpho-physiological and plant production traits were assessed by evaluating 81 rice genotypes collected from RARS, Pattambi and NRRI, Cuttack under water stress and irrigated conditions in the open field. Each genotype was raised in four rows of 2m length and was exposed to water stress at panicle initiation stage for a period of 25 consecutive days by withdrawing irrigation along with irrigated control and replicated twice. The morpho- physiological, and plant production traits were recorded after imposing water stress. Significant variation was observed for these traits under water stress condition. Genotyping of 81 rice genotypes were done using 100 SSR primers. Quality and quantity of DNA was checked. Amplification pattern of 100 primers were scored as per standard procedure. Population structure was calculated using the software “STRUCTURE” with genotypic score value. The molecular markers/ QTLs linked to drought tolerance and plant production traits were identified using the software, TASSEL 5. The result of the study revealed that morphological parameters such as the plant height at flowering was observed to be highest in PTB1 and lowest in ASD-16 under water stress condition in both experiments. The number of tillers were maximum for PTB7 (10.5 plant-1) and minimum for Kuttithekkan under water stress condition in both experiments. Delayed days to 50% flowering (7 days) was observed for the genotypes under water stress in two experiments compared to irrigated control. Physiological parameters such as Relative Water Content (RWC) decreased where as leaf temperature increased significantly in most of the genotypes under water stress condition. Highest leaf rolling (score – 7.78) was observed in Prathyasha in both experiment I (7.78) and experiment II (7.84). But the genotypes PTB55 (1.78) & PTB 29 (1.11) showed least leaf rolling symptoms in both experiment I and II respectively. Among the genotypes, the RWC was recorded to be highest in PTB15 (78.72%) while the lowest was recorded in Prathyasha (57.34%) under water stress condition in experiment I and in experiment II maximum relative water content was observed in PTB27 (72.98%) and minimum in ADT37 (50.25%). Membrane stability index was highest in PTB29 in experiment I (94.36 %) and in PTB27 in the experiment II (92.24%). Maximum leaf temperature was observed in PTB1 and minimum in Prathyasha under water stress condition in both experiments. Among the genotypes, chlorophyll stability index was recorded to be highest in PTB27 (95.59%) while the lowest in Pandichempan (80.36%) in experiment I, and in experiment II maximum was recorded in variety PTB7 (92.85%) and minimum in Pandichempan (75.52 %). The grain yield per plant under water stress condition was positively correlated with parameters such as tiller numbers, days to 50% flowering, relative water content, membrane stability index, chlorophyll stability index , spikelet fertility percentage and 1000 grain weight where as negatively correlated with leaf temperature, leaf rolling score, leaf drying score and percentage relative yield reduction. Under water stress the first principal component showed 41.77% variation, while second component exhibited 16.57% variation. Among the 14 morpho-physiological and plant production traits, relative water content, cell membrane stability index and chlorophyll stability index contributed towards maximum diversity. Under irrigated control condition the first principal component revealed 48.9 % variation, while the second component showed 16.57% variation. Among the 8 morpho-physiological and plant production traits studied, the relative water content and spikelet fertility percentage contributed towards maximum diversity. Clustering by Ward method was done to establish a relationship among the 81 rice genotypes. Similar types of genotypes were clustered together based on the phenotypic data. All the genotypes were clustered mainly into 5 clusters under water stress as well as irrigated control condition. Genotyping of eighty one rice genotypes were done using 100 SSR markers. Among them, 40 primers which demonstrated polymorphism among the genotypes were used to classify the genomic regions (QTLs) associated with drought tolerance and plant production traits through association genetic analysis. The marker trait association for all the traits under water stress and irrigated control condition were calculated using GLM and MLM model of TASSEL5 software. A total of 136 marker trait associations were observed while performing GLM analysis and MLM analysis resulted in 48 marker trait association based on the P and r2values in water stress as well as irrigated control condition. LD was distributed unequally on each chromosome and more concentrated on chromosomes 1 and 7. LD analysis in the whole population showed that there were significant LD pairs (P<0.05). A total of 52 LD pairs were observed under water stress and irrigated control conditions and out of these, there were 46 inter chromosomal LD pairs and 6 intra chromosomal LD pairs. The markers RM3825, RM455, RM490, RM259 and RM1026 showed significant associations with many phenotypic traits in water stress as well as irrigated control conditions. The Q-Q (Quantile-Quantile) plot also confirmed the association of these markers with phenotypic traits. In summary, there was significant variation for morpho-physiological and plant production traits among rice genotypes under water stress condition. Genotypes having higher relative water content, cell membrane stability index and chlorophyll stability index were found to be tolerant to drought. In the present study, the genotypes viz PTB28, PTB29, PTB30, PTB15, PTB7, PTB55, N-22 and Chomala identified as drought tolerant can be used in breeding programmes to improve drought tolerance in rice. From this study, 29 significant (P<0.05) marker trait associations were detected using mixed linear model (MLM). The identified most significant markers and their corresponding QTLs are, RM455 (Chromosome7) was linked to tiller number, leaf temperature, relative water content, yield per plant and spikelet fertility percentage. RM490 (Chromosome1) was associated with leaf temperature and chlorophyll stability index. Marker RM259 (Chromosome1) was associated with leaf temperature, chlorophyll stability index, leaf drying score, yield per plant and spikelet fertility percentage. RM1026 (Chromosome 9) was associated with leaf rolling score and drying score. Among them, RM 490 and RM259 showed co-location of QTLs for leaf temperature and chlorophyll stability index and RM259 & RM1026 showed co-location of QTLs for leaf drying score.ThesisItem Open Access Physiological approaches for manipulating male sterility in thermosensitive genic male sterile system for hybrid rice seed production(Department of Plant Physiology, College of Agriculture,Vellayani, 2019) Gayathri Rajasekharan, KAU; Roy StephenThermosensitive Genic Male Sterile (TGMS) plants which are male sterile above critical sterility temperature (CST) and male fertile below CST can be utilized as an efficient system for developing hybrid rice suitable to the state of Kerala. In this context, a study on ‘Physiological approaches for manipulating male sterility in thermosensitive genic male sterile system for hybrid rice seed production’ was conducted at the Department of Plant Physiology, College of Agriculture, Vellayani during 2015 to 2018 to evaluate the environmental conditions required for complete male sterility of TGMS plants and to manipulate the male sterility by using plant growth regulators and also to understand the molecular mechanism associated with TGMS system. The male sterile trait of stable TGMS line EC720903 from IRRI, Philippines, was transferred to red rice variety of Kerala, Jyothi. The CST of EC720903 was determined as 26.9⁰C and the critical thermosensitive phase was identified as 15-22 days before flowering. The seeds of BC1F2 plants were used for the experiment. The seeds were sown in pots in the open field and Rain Out Shelter (ROS) at monthly interval from June, 2017 to May, 2018 to evaluate the environmental conditions required for complete male sterility. The newly developed TGMS line exhibited complete pollen and spikelet sterility throughout the study period at both the experimental conditions since the average temperature prevailed during the critical thermosensitive period of TGMS red rice line was above the CST of 26.9⁰C. Anatomical studies of anther also showed that the TGMS lines were pollen free which is a preferred character of an ideal TGMS plant. The TGMS plants inside ROS had higher plant height, number of productive tillers and they flowered early compared to open field. Hence this low cost structure which is covered with a UV stabilized transparent sheet can be used for commercial hybrid seed production using TGMS lines throughout the year. 259 To maintain the sterility expression during the critical stages, the potential of plant growth regulators (PGR), were evaluated at RARS, Ambalavayal. Three PGRs, ethrel (400 mg L-1, 800 mg L-1 and 1200 mg L-1), salicylic acid (400 mg L- 1, 600 mg L-1 and 800 mg L-1) and maleic hydrazide (MH: 600 mg L-1, 800 mg L-1 and 1000 mg L-1) were applied as foliar spray at two stages viz., panicle initiation and two weeks after panicle initiation. The PGRs were capable of enhancing pollen sterility in all the treated TGMS plants. MH induced significantly higher percentage of pollen sterility (83.49%) compared control plants (19.92%). The external application of salicylic acid at three different concentrations induced 62- 82% of pollen sterility in rice and ethrel caused more than 75% pollen sterility. It was also observed that the PGRs applied were not inhibitory to the primary metabolism of TGMS lines. Hence spraying of MH (1000 mg L-1) two times at the time of panicle initiation and fifteen days after panicle initiation can be recommended to maintain male sterility. The TGMS line was hybridized with two rice varieties as pollen parents, Aiswarya (red) and Swetha (white) using proximal hybridization to evaluate the potential of using TGMS line as a female parent in Kerala condition. Seed setting was significantly high for the cross involving Swetha (40.07%). The F1 progenies obtained from two crosses along with parents and female parent EC720903 were sown in pots during April-May to September-October. The F1 progenies attained early flowering and physiological maturity. The protein content at panicle initiation stage was also high. Plant height, photosynthetic rate, transpiration rate and stomatal conductance at panicle initiation stage of F1 progenies of Swetha were significantly higher. The F1 plants did not show sterility and the seed setting percentage was in the acceptable range. Complete spikelet sterility was exhibited by the TGMS line since temperature was higher than CST. Molecular characterization of TGMS plants maintained at sterility inducing and fertility inducing conditions was done using samples collected from leaf and young panicle at ten days after panicle initiation. Protein profiling with SDS-Poly Acrylamide Gel Electrophoresis showed an enhanced expression of proteins at 25- 260 35 kDa, 35-48 kDa and 245 kDa under sterility inducing condition. In the panicle, increased expression at 17 kDa and presence of protein band at 245 kDa was observed at fertility and it was between 48-63 kDa under sterility inducing condition. Microarray gene expression analysis of TGMS leaf and panicle revealed that the genes encoding proteins similar to programmed cell death protein 2, Nuclear ribonuclease Z, hormone degradation and conjugation were up regulated and genes encoding proteins similar to male sterility protein 2, pollenless3, pollen-specific protein SF21 and no pollen were down regulated in the TGMS leaf under sterility inducing condition. The genes involved in hormone degradation and conjugation and programmed cell death protein 2 and genes encoding ABC transporter proteins required for exine and sporopollenin synthesis, lipid transfer protein and wax synthase, sucrose transporter, male sterility protein 2, β-1,3- glucanase and tapetal programmed cell death were down-regulated in the panicle. Pathways involved in the IAA, GA, brassinosteroid and jasmonic acid biosynthesis and carbohydrate synthesis and transport was down-regulated during sterility inducing condition in the TGMS line leaf and panicle. The TGMS line can be recommended to the state of Kerala as a female parent for the development of suitable red rice hybrids because of its stable sterility. If the temperature of a particular location goes above 27⁰C in a particular season that period can be used for hybrid seed production. Application of MH (1000 mg L-1) at the time of panicle initiation and fifteen days after panicle initiation is more effective in sterility manipulation when there is drop in temperature. Occurrence of pollen free anthers in the TGMS line during sterility inducing condition is mainly due to the down-regulation of genes encoding ABC transporter proteins, lipid transfer protein and strictosidine synthase, glucosemethanol- choline oxidoreductase, male sterility protein 2, wax synthase and β- 1,3-glucanase.ThesisItem Open Access Evaluation of CO 2 enrichment effects on resource utilization in cowpea and amaranathus(Department of Plant Physiology, College of Agriculture, Vellayani, 2019) Srikanth, G A; KAU; Manju, R VThe current experiment entitled "Evaluation of CO2 enrichment effects on resource utilization in cowpea (Vigna unguiculata L.) and amaranthus (Amaranthus tricolor L.)" was undertaken with the objective to study the impact of CO2 enrichment on cowpea and amaranthus imder varying moisture, temperature and nutrient regimes. Four sets of pot culture experiments were conducted during 2015 to 2018 with two varieties of cowpea, Lola and Vellayani Jyothika and Arun variety of amaranthus. The technology used for CO2 enrichment was Open Top Chamber (OTC) system established under Department of Plant Physiology, College of Agriculture, Vellayani. Carbon dioxide was released from CO2 cylinders to one of the two OTC's bringing the CO2 level to 600 ppm and the second OTC worked as control at ambient CO2 for chamber effect. The experiments were laid out in CRD factorial. First experiment was conducted to study the varietal variation in cowpea in response to CO2 enrichment through OTC. Experimental plants were maintained in OTC from sowing to harvest. Observations were taken at biweekly intervals till 3 months. In this study highest values were recorded in variety Lola for number of leaves per plant (79.5), specific leaf area (208.78 cm^g"'), root weight (14.91 g), shoot weight (65.05 g), root shoot ratio (0.229), total dry matter production (79.98g), single pod weight (12.88 g), number of seeds per pod (12.34) and early flowering was also observed under elevated CO2 condition. In Vellayani Jyothika, highest values were recorded for number of pods per plant (11.75), total yield (102.59 g/plant) and total chlorophyll content (0.897 mg g"^), stomatal frequency (2203.84 cm'\ starch (14.26 mg g"') and reducing sugar (15.97 mg g"'), and fibre content (1.34 mg g"') under elevated CO2 condition. Parameters like total soluble protein recorded lower values (8.75) under CO2 enrichment. Quality parameters were modified with a reduction in total protein content (15.76, 14.75 mg g"') and increase in fibre content (1.34, 1.23 mg g '). Among the two varieties of cowpea, Vellayani Jyothika was found to be the best responding variety to elevated CO2 in terms of yield parameters and so was selected for further experiments. In the second experiment evaluation of plant response to elevated CO2 under different soil moisture regimes were evaluated. Two weeks old potted plants were shifted to OTCs. All the three sets of plants were maintained at field capacity (FC) initially. Soil moisture levels were brought down to 80% and 70%, in the second and third sets 30 days after planting and were maintained for a period of 30 days at these soil moisture regimes in OTCs. The result indicated an improvement in growth performances of cowpea and amaranthus under mild and severe moisture stress conditions (80% and 70% FC) in terms of increased number of leaves (46.82, 43.22), specific leaf area (360.43, 261.58 cm^ g-') root weight (9.02, 8.51 g), shoot weight (30.56, 22.16 g), root shoot ratio (0.327, 0.216) and dry matter production (38.98, 29.67g) respectively. The same trend was found in the case of amaranthus for number of leaves per plant (41.00, 37.66), specific leaf area (171.25, 157.59 cm^ g'), plant height (79.66, 72.32 cm), root weight (0.840, 0.416 g), shoot weight (4.740, 3.031 g), root shoot ratio (0.197, 0.130) and dry matter production (4.82, 4.71 g). In the case of cowpea CO2 enrichment induced early flowering in all the three soil moisture conditions. Significant increase in yield was also obtained under stress condition (78.51 and 77.08 g/plant) due to increase in number of pods per pod (8.67, 7.32), single pod weight (11.63, 10.36 g), number of seeds per pod (9.33, 8.75) both under 80% and 70% PCs. In cowpea, total chlorophyll content (1.671, 1.238 mg g"'), RWC (85.24, 77.97 %), stomatal frequency (2144.00, 1964.53 no cm"^), starch (6.12, 5.69 mg g"'), reducing sugar (12.48, 12.09 mg/g), phenol content (0.943, 0.801 mg g') free amino acid content (5.960, 4.823 mg/g), SOD activity (3.466, 4.230 g-Wnute-'), ascorbic acid content (6.87, 5.84 mg/lOOg). Reduction of transpiration rate (0.547, 0.335 mmol water m-^ s"') total soluble protein (6.02, 5.13 mg g'^), membrane integrity (% leakage) (37.80, 34.61%) under CO2 enrichment after stress. The same trend was found in the case of amaranthus total chlorophyll content (1.245, 1.206 mg g"'), RWC (84.98, 79.37%), stomatal frequency (691.16, 573.78 no cm'^), reducing sugar (17.61, 13.56 mg g"'), starch (2.66, 2.53 mg g"'), phenol content (6.20, 3.53 mg g"') free amino acid content (1.071, 1.036 mg g'), SOD activity (1.842, 1.526 g-'minute-'), ascorbic acid content (36.93, 28.40 mg/lOOg), reduction of transpiration rate (2.093, 1.410 mmol water m- s ) total soluble protein (15.42, 15.06 mg g '), membrane integrity (3.480, 3.017%) under elevated CO2. Evaluation of plant responses to elevated CO2 under different soil nutrient regimes was earned out in the third experiment. Potted plants of cowpea and amaranthus (Variety Arun) were used for conducting the experiment. Plants were maintained at FC at four nutrient levels throughout the crop period. The best performance given by plants receiving nutrients as per POP recommendation along with 25% extra nitrogen In cowpea, the values were recorded as follows, number of leaves (76.00), specific leaf area (468.95 cm^ g"^), dry root weight (42.0%), dry shoot weight (0.5%), root shoot ratio (4.9%). total dry matter production (117.58 g), number of pods per plant (16.66), single pod weight (15.83 g), number of seeds per pod (13.33) and total yield (169.53 g/plant). In the case of physiological and biological parameters also this level of nutrient application recorded maximum values for total chlorophyll content (1.528 mg stomatal frequency (2782.01 no cm"^), total soluble protein (20.25 mg g'), starch (13.88 mg g"'), reducing sugar (14.65 mg/g), total protein (15.25 mg g ) and fibre content (1.18 mg g"') and The highest number of root nodules per plant (45.26) and highest nutrient use efficiencies for N, P and K (1.013, 2.675, 0.293 g) were recorded under this treatment. In amaranthus, higher values were recorded in for number of leaves per plant (52.11), specific leaf area (316.20 cm^ g"'), dry root weight (2.13 g), dry shoot weight (4.34 g), root shoot ratio (0.64 g) and total dry matter production (10.47 g). Total chlorophyll content (1.542 mg g"'), stomatal frequency (705.64 no cm"^), total soluble protein (20.25 mg g"'), starch (3.29 mg g"'), reducing sugar (23.14 mg g"'). Calcium content (23.69 mg g'), Fe content (6.71 mg g"') and ascorbic acid content (43.51 mg/lOOg), under elevated CO2 condition. Though a C4 plant like amaranthus also responded to CO2 enrichment, extend of increase in growth and dry matter production was less compared to cowpea, which can be due to the mnate CO2 enrichment mechanism present in C4 systems. The fourth experiment was conducted to study the temperature and humidity interaction with CO2 enrichment. Potted plants of cowpea and amaranthus (variety Arun) were used for conducting the experiment. Plants were maintained at EC throughout the crop period as per POP recommendations of KAU. One set of plants were exposed to mist and the second set was maintained without exposure to mist. In cowpea, highest values were recorded by plants exposed to mist for number of leaves per plant (76.14), specific leaf area (471.07 cm^ g"'), dry root weight (21.74 g), dry shoot weight (72.46 g), root shoot ratio (0.302), dry matter production (104.2 g), single pod weight (15.93 g), number of pods per plant (18.75), number of seeds per pod (14.00), total yield (175.36 g/plant), RWC (96.48%), total chlorophyll content (1.651 mg g'^), stomatal frequency (2724.83 no cm"^), starch (13.29 mg g'^), reducing sugar (15.71 mg g"'), phenol (1.128 mg g"'). Free amino acid (6.398 mg g"'), SOD activity (3.56 g-Wnute-') and ascorbic acid content (9.36 mg/lOOg), Early flowering was induced in this set of plants. Parameters like transpiration rate (1.394 mmol water m-^ s"') total soluble protein (8.82 mg g"'), membrane integrity (43.92% leakage) recorded lower values under CO2 enriched treatments. In amaranthus, higher values were recorded under mist condition for number of leaves (48.51), specific leaf area (327.68 cm^ g"') dry root weight (2.160 g), dry shoot weight (6.74 g), root shoot ratio (0.517), dry matter production (8.90 g). RWC (95.38 %), Total chlorophyll content (1.382 mg g"'), stomatal frequency (694.02 no cm"^), starch (4.19 mg g'), reducing sugar (23.02 mg g"'), phenol (7.92 mg g"'), Free amino acid (1.536 mg g"'), SOD activity (2.44 g-'minute-') and ascorbic acid content (42.75mg/100g). Parameters like transpiration rate (12.36mmol water m-^ s ), total soluble protein (19.05 mg g') (25.40 %) and membrane integrity (% leakage) (6.47 % leakage) recorded lower values. Significant improvement in plant performance and increase in yield are seen under CO2 enrichment with mist exposure in the cases of cowpea and amaranthus The present study shows the existence of varietal variation in the crop responses under CO2 enrichment gives option for selection of varieties with better yield and quality under the changing climatic condition. Elevated CO2 concentration is found to be improve stress tolerance through better photosynthetic rate and activation of defence mechanism. Improved production technologies can be developed especially with mist facility with minimizing irrigation requirement. This can also be utilized for enhancement of antioxidant production which are economically valuable secondary metabolites. Exploitation of soils lacking sufficient nutrient and water can be done through the introduction of low cost CO2 enrichment methods. Since soil moisture and temperature are the primary determinants of nutrient availability and acquisition plant nutrition can strongly be influenced by global climate change. This necessitates site specific CO2 enrichment studies. The present study showed the existence of varietal variation in the crop responses under CO2 enrichment which gives option for selection of varieties with better yield and quality under the changing climatic scenario. Elevated CO2 concentration is found to improve the performance of plants grown under low soil moisture levels by improving the performance of photosynthetic machinery and by activating defence mechanisms. Based on this, improved high-tech agriculture production technologies with mist facility can be developed with minimum irrigation requirement which will ensure maximum water use efficiency. This also gives a possibility of utilizing the interactive effects of different cultivars, CO2 enrichment, and other abiotic factors for enhancing the production of antioxidants, many of which are economically valuable secondary metabolites. The present programme also opens up possibilities of quality improvement of agricultural products based on the interaction of elevated CO2 with factors like cultivars, growth stages, light, nutrient and abiotic stress factors. Intensification of cultivation and quality improvement are equally important to address the new challenges of global health because many of the economically important crops, when grown under field conditions at the elevated atmospheric C02were reported to have deleterious impacts on quality. The present study indicated the improved performance of cowpea under CO2 enrichment with additional nitrogen input. This points towards the changing nutrient requirement of crop plants under the current scenario of increasing CO2 concentration and suggests for bringing out modifications in the nutrient recommendations with additional nutrients, especially nitrogen. Exploitation of soils lacking sufficient nutrient and water also can be done through the introduction of low cost CO2 enrichment methods. Since soil moisture and temperature are the primary determinants of nutrient availability and acquisition, plant nutrition can strongly be influenced by global climate change. So this study also points to the requirement of site specific CO2 enrichment studies.ThesisItem Open Access Nutrio-physiological and molecular analyses and carbon dioxide enrichment studies of coconut palms (Cocos nucifera L.) with foliar yellowing(Department of Plant Physiology, College of Agriculture, Vellayani, 2017) Deepa, S; KAU; Manju, R VA study entitled “Nutrio-physiological and molecular analyses and carbon dioxide enrichment studies of coconut palms (Cocos nucifera L.) with foliar yellowing” was carried out with the objective to analyze the nutrio - physiological changes occurring in the palms affected with foliar yellowing and to assess the impact of enhanced carbon dioxide on phytoplasmal response. In this study, palms showing mid whorl yellowing (MWY), root (wilt) affected palms (RW) and healthy palms were selected from two different locations viz the Instructional Farm, College of Agriculture, Vellayani (location 1) and Venganoor region (location 2) in the Thiruvananthapuram district. Coconut seedlings showing yellowing were selected from the Instructional Farm, College of Agriculture, Vellayani to study the effect of enhanced carbon dioxide on phytoplasmal response. Catharanthus and brinjal plants with ‘little leaf symptom’ maintained at the Department of Plant Pathology were utilised for grafting into healthy catharanthus and brinjal plants and these were also taken for studying the phytoplasmal response under elevated carbon dioxide condition. Physiological and biochemical analyses revealed significant variations in all the parameters studied. Palms with mid whorl yellowing (MWY) showed a significant reduction in the chlorophyll a, b and total chlorophyll contents, relative water content, membrane integrity and phenol content compared to the healthy palms. An increase in the protein (88%), carbohydrate (25.14%), reducing sugar (28%) and starch content (28.33%) was noted in palms with MWY. In the case of antioxidant enzymes there was build up of polyphenol oxidase (145.38%) and peroxidase activities in palms with MWY compared to the healthy palms. A similar trend was observed in almost all cases of RW affected palms. Nutrient analyses revealed significant alterations in the nutrient content of the selected palms. Significant reduction in the nitrogen (47.74%), magnesium (22.72%) and zinc content (24.19%) was observed in palms with yellowing compared to the healthy palms. Accumulation of elements like potassium (37.96%) calcium (40.79%), iron (54%) and copper (35.75%) was observed in palms with mid whorl yellowing compared to the healthy palms. These variations in the nutrient levels can have an influence on symptom development in coconut palms. The results on the soil nutrient analyses did not show any particular role in development of yellowing symptoms. Phytoplasma cells were detected in the phloem tissues of both mid whorl yellowing and root wilt affected palms under Scanning Electron Microscopy (SEM) study. Morphological and anatomical analyses of fresh roots indicated browning and necrosis of roots and vascular disintegration in MWY and RW affected palms. The presence of phytoplasma in the selected samples were checked by nested PCR analysis using phytoplasma specific universal primers-P1/P7- R16F2n/ R16R2, Phytoplasma 16S rDNA specific semi nested primers 1F7/7R3 - 1F7/7R2 and by real time PCR technique using real time primers QPF2/R2. Semi- nested PCR yielded an amplicon of 493 bp in all the MWY and RW palms in both the locations. Real time PCR yielded an amplicon of 140 bp in the RW palms, 3 MWY palms in location 1. Nested PCR with phytoplasma specific universal primer pairs P1/P7-R16F2n/ R16R2 yielded an amplicon of 1.2 kb in MWY palm and RW palm. Sequence analysis of the mid whorl yellowing phytoplasma revealed 89% similarity to the root wilt phytoplasma. In experiment II, nested PCR with universal primer pairs showed no amplification in the coconut seedlings and hence only catharanthus and brinjal grafts with phytoplasmal infection were kept in Open Top Chamber (OTC) with 500 ppm Carbon dioxide concentration for a period of one month. After the exposure period, the plants kept in OTC showed an increased rate of growth and development with phytoplasmal symptoms. Physiological and biochemical analyses showed a significant increase in the reducing sugar content (63%), protein content (147%) and PAL activity (32%) and significant reduction in the phenol content (37%), and polyphenol oxidase activity (62%) in the infected plants kept in OTC compared to the infected plants kept in open condition. Molecular analyses of the infected samples using real time PCR kept in OTC and open condition with the DNA samples isolated at the 15th and 30th day of exposure was done. No significant variation was observed in the phytoplasmal load after elevated carbon dioxide exposure. The role of phytoplasma in causing MWY was established by molecular and anatomical studies. Sequencing of the PCR product revealed that MWY phytoplasma can be a variant of root (wilt) phytoplasma. The present study indicated that the overall health status of the palms with MWY was highly deteriorated. Significant variation in the nutrient profile was noted which emphasise the need for proper nutrient management. Semi- nested PCR was found to be more accurate and specific in phytoplasmal detection which can be utilised for phytoplasmal indexing and mother palm and disease free seedling selection. Elevated carbon dioxide showed an improved growth and development and activated defense response to phytoplasma in the infected plants but the CO2 induced modifications in phytoplasmal load was not detected. The results indicated a better tolerance strategy to environmental conditions. phytoplasma under changing
