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Open Access
Physiological aspects of ex vitro establishment of tissue cultured orchid plantlets
(Department Of Plant physiology, College Of Agriculture, Vellayani, 2000) Samasya, K S; KAU; Viji, M M
The present investigation was undertaken to elicit information on the physiological, morphological, biochemical, biometric and anatomical changes during in vitro propagule multiplication and ex vitro establishment in tissue cultured plantlets of orchids. Dendrobium hybrid Sonia 17 was the variety used for the study. The rooting media was supplemented with different levels of sucrose. At the time of planting the plantlets were subjected to triazole treatment. During the process of hardening the plantlets were maintained in hardening chambers with different levels of light and humidity. Among growth parameters the crop growth rate (CGR), net assimilation rate (NAR) and relative growth rate (RGR) were found to be high at 40 gIl of sucrose concentration. The CGR of these plantlets were on par with normal green house grown plantlets. The photosynthetic rate was found to increase and the transpiration rate was found to decrease at 40 gIl of sucrose . concentration. The maximum survival percentage of the in vitro plantlets occur when 40 g11 of sucrose incorporated in the rooting medium. This may be attributed to the influence of the sucrose concentration on morphological characters studied viz. plant height, number of leaves per shoot and number of roots per shoot. With regard to photosynthetic pigments an increase in the content of total chlorophyll, chlorophyll a chlorophyll b and carotenoids occurred in plantlets treated with 40 g/1 of sucrose. Also the protein content and carbohydrate content was maximum at the above sucrose level. The leaf area, root length, total fresh weight and dry weight of the plantIets maintained at 40 gIl of sucrose level were higher than other treatments. These effects ultimately lead to better survival percentage. Triazole treatment of plantIets during planting out helped in better survival percentage. With regard to the growth parameters the effect was distinct towards the later stage of growth. CG~ NAR and RGR were maximum on the triazole treated (5 mgll) plantIets and was comparable to normal green house grown plants. There was marked increase in the photosynthetic rate and decrease in transpiration rate of plantIets treated with 5 mgll of triazole. However the photosynthetic rate of normal green house grown plants were much more than the tissue cultured plantIets. Regarding morphological characters, increasing concentration of triazole had negative influence on plant height. However plant height of normal green house grown plants were distinctively higher than tissue cultured plantIets. With regard to number of leaves per shoot, triazole treatment showed significant effect only after 30 days of planting out, whereas the number of roots per shoot was very much influenced by triazole. The maximum number of roots was produced at 5mgll of triazole treatment and these effects in turn influenced higher survival percentage of plantIets. ------....- ....- ~ - - - ----- Regarding the biochemical aspects total chlorophyll, chlorophyll a, chlorophyll b and carotenoids contents of plantlets treated with triazole (5 mg/l) were higher and found to be on par with that of green house grown normal plants towards the later stage. The protein content was also positively influenced by triazole treatment (5 mgll) and the value was comparable to that of normal plantlets. In the case of carbohydrate content the treatment becomes statistically significant and the normal green house grown plants exhibited distinctively higher value. The plantlets treated with 5 mgll of triazole were found to have higher leaf area, root length, root: shoot ratio, total fresh weight and dry weight than other treatments. However the root shoot ratio and total fresh weight of treated plantlets were on par with the normal green house grown plants towards the later stage viz, 45DAP. The physiological, morphological, biochemical and biometric characters of the plantlets were also found to be influenced by different levels of light intensity and humidity maintained in the hardening chamber. Among the different treatments, plantlets grown at 50 percent light intensity and 70 to 90 percent relative humidity exhibited higher CG~ NAR and RGR. Also these plantlets exhibited a marked increase in photosynthetic rate and decrease in transpiration rate. However CGR and NAR of green house grown normal plants were distinctively higher during the later period. However the normal plants had distinctively higher CG~ RGR and photosynthetic and very less transpiration rate than other treatments. The plantlets grown under 50 percent light intensity and 70 to 90 percent humidity produced maximum plant height, number of leaves and number of roots per shoot. The survival percent of the tissue cultured plantlets in the field condition (green house) was found to be superior under appropriate environment of light and humidity (50 percent light intensity and 70 to 90 percent relative humidity) There was not much significant difference among the treatments of light and humidity in the case of pigment content. However the plantlets grown in the hardening chamber maintained at 50 percent light intensity and 70 to 90 percent of relative humidity recorded maximum value of total chlorophyll, chlorophyll a, chlorophyll b and carotenoids among treatments and the normal green house grown plants exhibited distinctively higher pigment content. The normal plantlets recorded marked increase in protein content and carbohydrate content than the tissue cultured plantlets. In the present study, an environment of 50 percent light intensity and 70 to 90 percent relative humidity was found to be superior and could favour enhanced leaf area, total fresh weight, total dry weight and root length of plantlets which ultimately resulted in better survival percentage. The in vitro plantlets observed to have anatomical characters as compared to the normal green house grown plants and hardened plantlets. The stomata remained open and less number of stomata per unit area of leaf was observed as the in vitro leaves were concerned. Another peculiarity of the in vitro plantlets was the absence of cuticle layer. The mesophyll layers were also found to be less compared to normal plantlets. These anatomical characters were one of the severe limitations of the micropropagated orchid plantlets during ex vitro establishment which ultimately resulted in high rate of field mortality.
Open Access
Biochemical and molecular studies on post-harvest physiological deterioration of cassava (Manihot esculenta crantz)
(Department of plant physiology, College of agriculture,Vellayani, 2015) Saravanan, R; KAU; Roy Stephen
The project entitled “Biochemical and molecular studies on post-harvest physiological deterioration of cassava (Manihot esculenta Crantz)” was conducted at the Dept of Plant Physiology, College of Agriculture, Vellayani and at ICAR-CTCRI, Thiruvananthapuram during 2013 to 2015. The main objective of the work was to analyse the physiological biochemical and molecular mechanisms associated with post harvest physiological deterioration (PPD) and develop methods to delay the PPD in cassava. The initial screening of the cassava genotypes for their performance of PPD was done with 61 different genotypes including some released varieties. Significant differences were observed for PPD development and shelf-life of harvested roots. Cassava genotypes such as IMS2-8, 9S-172, 11S-53, IRS 2-10 and 9S-286 started showing the visible discolouration in the parenchyma tissue earlier (less than 3 days of storage). Genotypes such as 9S-7, 9S-98, 11S-31, 11S-86, 11S-14, CE63-3, CI43-2, CR43-2, CR54-A5, CR59-8R, Sree Athulya and Kalpaka showed low PPD scores and better shelf-life. Tissue imprinting for peroxidase enzyme showed that there was a remarkable increase in peroxidase activity in the root tissues with increasing PPD symptoms. There was no correlation between the root morphological traits and PPD severity. Carotene and starch content of root did not influence the PPD in the genotypes studied. Chemotypic profile of roots with PPD symptoms was used to classify the genotypes based on PPD. To develop an objective screening tool, Near Infrared Spectroscopy (NIRS) was utilized to analyse root samples for PPD. Principal component analysis (PCA) and chemometric tools clearly grouped the different PPD category in root tissues. Various stains such as saffranin, aniline blue, erythrocin, fast green and phloroglucinol stained the tissue specifically at vascular tissues and other cell components and were not suitable for detecting PPD. Storage techniques such as storing the harvested roots in de-aerated bags, wax coating and burying the roots under the soil were employed with selected cassava varieties like Sree Athulya, Sree Jaya, Vellayani Hrashwa, Kalpaka and Sree Padmanabha to delay PPD. Wax coating was suitable to reduce PPD for few weeks. Effect of different storage temperature on PPD was studied for five cassava varieties. Root respiratory flux was higher in roots stored at ambient conditions compared to high (40o C) or low temperature (4o C) storage. There were significant positive correlation between root respiratory flux at 3 and 9 days of storage to the CAT and POX activities studied in different cassava varieties. Roots were treated with various food preservatives at two different concentrations (0.5 and 1%). There was a weak, but significant reduction in symptom development in butylated hydroxy touline – (BHT, at 0.5 and 1% level) treated roots compared to other treatments. Nearly three folds increase in total phenol content was noticed in BHT and butylated hydroxy anisole (BHA) treated roots. The plant hormones related to wound response such as Salicylic acid and jasmonic acid were used to study the PPD response in roots under storage. The roots did not show marked influence to hormone application. Significant genetic variation was observed for PPD. The low PPD type genotypes such as 9S-7, 9S-98, 11S-31, 11S-86, 11S-14, CE63-3, CI43-2, CR43-2, CR54-A5, Sree Athulya and Kalpaka can be utilized for breeding programmes. High temperature storage of cassava at 40 oC resulted in reduced respiratory rate and increased antioxidant scavenging enzyme activity and also reduced the PPD. Differentiation of cassava roots at the metabolites level corresponding to visual symptoms and chemotypic profile of PPD and NIR spectroscopy offer a rapid screening tools. Among the different storage treatments, wax coating with antiseptic pre-treatment is most suitable and economical for increasing shelf-life of roots. Food preservatives like BHT and BHA have a significant, albeit marginal influence on PPD symptom development in cassava.
Open Access
Influence of host plants and soil moisture stress on the water relations in sandal
(Department of Tree Physiology and Breeding, College of Forestry,Vell, 2006) Dhaniklal, G; KAU; Asokan, P K
The influence of host plants and soil moisture stress on water relations in sandal was investigated in a pot culture experiment at College of Forestry, Kerala Agricultural University, Vellanikkara. Five host plants, Divi divi (Caesalpinia coriaria Jacq.), Casurina (Casuarina equisetifolia J.R & H.G. Forst), Pongamia (Pongamia pinnata (L.) Pierre), Lantana (Lantana camara L.) and Erythrina (Erythrina indica Lamk.) were selected for this study. The results showed that Sandal seedlings with and without host showed similar height increment, except when erythrina was the host. The host plant had no influence on most of the growth parameters of sandal seedlings. The collar diameter of sandal seedlings with and without host was on par during the early seedling stage and by the end of the experimental period it showed a significant difference. There was no significant difference in the number of leaves, leaf area and root length of sandal with different hosts. Haustorial connections were not recorded even after the experimental period. Sandal seedlings with Erythrina indica as host decreased the pre dawn water potential. Water stress decreased the seedling height, collar diameter, number of leaves, leaf area, shoot dry weight and total dry weight of sandal seedlings. Fully irrigating the pots once in three days resulted in better growth of sandal seedlings as compared to irrigation once in six days. Water stress increased the root length and root dry weight. Root length was found to be more for sandal seedlings which were irrigated once in six days compared to that, irrigated once in three days. Water stress decreased leaf area of sandal seedlings. Transpiration rate at 14:00 hrs was found to be more than that of transpiration at 8:00 hrs. Transpiration rate decreased with increase in soil moisture stress. Pre dawn water potential was lower for sandal seedlings irrigated once in six days compared to that irrigated once in three days. As the haustorial connections were not observed even after 270 days after planting it can be concluded that the difference in the seedling growth parameters of sandal with some of the hosts is due to the above and below ground competition for sun light, water and nutrients.
Open Access
Studies on the physiological and biochemical changes in relation to reproductive efficiency in Chickpea (Cicer arietinum L.)
(Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi, 1981) Seshadrinath, S; KAU; Sabra Abbas
The average yield of chickpea in India is as low as 700 kg/ha. One of the major causes for this low yield can be attributed to the low reproductive efficiency. The cause for low reproductive efficiency is mainly due to heavy shedding of reproductive structures. The present investigations were, therefore, initiated with the following objectives: 1) To study the genetic variability and diversity with reference to the flowering behaviour and shedding of flowers during the reproductive stage in order to evaluate the peak periods of flowering, shedding percentage and reproductive efficiency.
Open Access
Physiological and biochemical basis of degeneration in Root (Wilt) affected coconut palm
(Department of Agricultural Botany, College of Agriculture, Vellayani, 1983) Sheela Cherian; KAU; Abraham, A T
Several studies on the physiological and biochemical aspect of the root (wilt) disease have been carried out and conclusions have been drawn. A recent study comprising o f the estimation of protein non protein amino acids and cytokinin from the leaf, root and developing nut o f healthy# apparently healthy and root (wilt) affected coconut palm was carried out in tills, laboratory (unpublished). The chlorophyll content of leaves was also estimated. The present study comprised o f estimation o f gibberellin s and abscissic acid from the leaf# root and nut of healthy apparently healthy and five different intensities of root (wilt) affected coconut palms. The results of the biochemical analysis show that in the root (wilt) affected coconut palms there are alterations or deviations in normal metabolic activities from that o f healthy palms. Earlier work done has shown a reduction in cytokinin content in the root(wilt) affected palm in addition to protein and chlorophyll content. The present study has revealed a deficiency of gibberellins another important growth regulator and an accumulation of the growth inhibitor abscissic acid in the root(wilt) affected palms. The site s of synthesis and / interconversion o f gibberellins are damaged together with the impairment o f the translocation system. Increased respiration lowered CO2 fixation and severe damage o f the shoot system in the later stages are in brief the in tern al and external expressions o f the root (wilt) syndrome. Thus the shoot and root system which are interdependant are unable to function in harmony leading to a failure in their growth and development. An accumulation of ABA along with a reduction in gibberellin level might be the reason for the stunting syndrome seen in root(wilt) affected palms.
Open Access
Photosynthetic efficiency and productivity of gynoecious parthenocarpic cucumber in naturally ventilated poly house
(Department of plant physiology, College of horticulture, Vellanikkara, 2015) Gayathri, Rajasekharan; KAU; Nandini, K
Poly house cultivation of vegetables is an emerging approach for production of vegetables in Kerala. The main principle of poly house cultivation is the facilitation of favourable micro-climates, which favour maximum production. The top of poly house is cladded with UV-stabilised plastic sheet which selectively screen the various spectral components of solar radiation and transform direct sunlight into scattered light inside. This type of spectral manipulation is aimed to specifically promote desired physiological processes and to modulate morphological and photosynthetic responses of plants. Hence, basic information on the physiological aspects involved in the photoresponse of crop in poly house is needed to realize maximum yield potential. In this context, a study was undertaken in a farmer’s field at Thannyam to compare the photosynthetic productivity of gynoecious parthenocarpic cucumber in poly house and open condition. High light intensity, Ultra violet (UV) radiation and Photosynthetically Active Radiation (PAR) caused a stressful environment which in turn reduced most of its morphological and biochemical characters in cucumber grown under open condition. However ambient CO2 concentration, which decides the photosynthetic rate was more under polyhouse condition. Poly house cladded with UV stabilized sheet, reduced light intensity, UV-radiation and PAR favoured most of the morphological characters of the crop. The morphological characters like leaf area, Leaf Area Index (LAI), number of leaves, number of nodes and internodal length were significantly high for poly house grown cucumber. The chlorophyll content- Chl a, b and total chlorophyll in leaves was significantly high when grown under poly house. However, the activity of IAA Oxidase (IAAO) observed at 15 and 60 DAS was significantly lower inside the poly house indicating auxin availability for morpho-physiological fuctions. The Gibberelic acid content also increased but significant difference was observed only at 75 DAS in poly house grown crop. Photosynthetic rate of the crop under both conditions when recorded gradually increased from 15 DAS to 45 DAS and thereafter declined. This was significantly high under open condition at 15, 30 and 45 DAS, whereas it was significantly high in poly house only at 60 and 75 DAS. The poly house crop could maintain higher photosynthetic rate even at later growth stages of crop thereby prolonging the crop duration. Transpiration rate was significantly high under open condition at 30 DAS, but significantly higher values were observed in poly house condition at 45 and 75 DAS. The lower photosynthetic rate was due to low influx of CO2 in to mesophyll cells which is evident from low intercellular CO2 concentration in the poly house crop. This is also related to high stomatal resistance inside the poly house at 15 and 30 DAS. The carboxylation efficiency, which relates to photosynthetic rate, was significantly high at 60 and 75 DAS in the poly house crop. The photochemical efficiency of PS II as indicated by Fv/Fm ratio was higher under poly house environment. Canopy temperature depression did not give any significant difference between two conditions. Light absorption coefficient was significantly high in open condition where the LAI was less. The lower values of light absorption coefficient observed inside the poly house may be related to high LAI. There was no significant difference in number of days to flowering and days to first harvest between open and poly house grown crops. But the number of days to last harvest and number of harvests made from poly house grown crop were significantly high when compared to open condition. The yield contributing components such as number of fruits per plant, fruit weight, yield per plant and marketable yield were significantly high for poly house grown crop. Early senescence of the crop was observed under open condition compared to poly house. Retention of more chlorophyll content even at later stages of crop delayed senescence in poly house grown crop. The ascorbic acid content, one of the quality parameter was significantly high in crop grown under open condition. Organoleptic evaluation of fruits revealed that the poly house grown crops maintained significantly high colour, texture and overall acceptability of the fruits. This study suggests that the diffused light and equal distribution of radiation over the crop canopy favoured morphological characters of poly house grown crop. This in turn helped the crop to maintain high photosynthetic rate and carboxylation efficiency even at later stages of the crop which resulted in increased number of harvest in poly house.
Open Access
Growth and physiology of isachne miliacea roth. in different soil types and its sensitivity to common herbicides
(Department of plant physiology, College of horticulture, Vellanikkara, 2015) Suada, A P; KAU; Girija, T
Isachne miliacea Roth. is one of the predominant weed in the low land rice fields of Kerala. The weed belongs to the family poaceae. Locally it is known as ‘Chovverippullu, Naringa, Njammal, Changalipullu.’ Previous studies conducted in Kerala Agricultural University showed that I. miliacea alone can contribute to 61 per cent reduction in the production of rice in Onattukara region. Presently, the weed is reported to be spreading to other rice growing regions of Kerala. It is found both during the Rabi and Kharif seasons. Eradication of the weed is very difficult, as it is propagated through seeds and stem cuttings. Hence a study was proposed to understand the growth and propagation of I. mliacea in different rice growing soils and also to understand the response of the weed to common herbicides popular in the state. The effect of different soil types on growth and phenology of I. miliacea was studied in pot culture with soil collected from five different rice growing regions viz. Onattukara, Kole, Kuttanad, Pokkali and Palakkad. Ten kg soil each was filled in plastic boxes of size 50 x 25 cm and five replications was maintained for each soil type. Ten seeds were sown in each box and the germination was noted. At two leaf stage when the seedlings were identifiable, a single seedling was retained in each box and the excess seedlings were removed, irrigated regularly and the different phenophases and the morphological attributes were observed at 15 days interval. The study showed that soil type had a profound influence on the phenology and growth pattern of the weed. Due to high acidity (pH -3.6) and salinity (EC – 4.46 dS/m) seeds sown in Pokkali soils did not germinate. Plants grown in Kuttanad soil showed earlier germination, tillering, flowering, seed formation and seed maturation, while those from Palakkad soil required more number of days to reach these phenophases. The variation in morphological attributes such as total shoot length, leaf number, internodal length, number of panicles and seeds produced per plant were significant. Plants grown in Palakkad soil had higher total shoot length and internodal length as compared to Kuttanad soil, but the leaf number, number of panicles per plant and number of seeds produced per panicle were higher in Kuttanad soil, where the potassium, phosphorus and organic content was higher compared to other soils. As the nutrient status of Onattukara and Kole land soils were similar (potassium, phosphorus, magnesium, zinc, manganese and sulphur), the performance of the weed in those two soil types were also on par for many of the morphological characters. Propagation of I. miliacea was affected by ambient temperature, shade, depth of burial and moisture level of soil. The seeds germinated when the temperature range was between 15 - 400C, the highest germination was obtained at 250C. Growth of the weed was highest in open condition compared to shaded condition. Under 50 per cent shade, seed germination declined by 70 per cent. Higher germination per cent of weed was obtained under moist condition, while stem cuttings performed well in both moist and submerged condition. The germination per cent of the weed, reduced with depth of burial. Sensitivity of the weed to pre emergence herbicides was tested using seed bioassay technique. In the first set, herbicide soaked filter paper was placed at the bottom of petri plates and seeds were placed on it (TP method). In the second set, the herbicide soaked filter paper was placed on top of the seeds and another water soaked filter paper was placed at the bottom (BP method I). In the third set, seeds were placed in between two filter paper soaked with herbicides (BP method II). BP method II gave the best result for all the pre emergence herbicides. However, oxyfluorfen and butachlor showed higher weed suppression in all the methods tried. Sensitivity of the weed to post emergence herbicides was tested using whole plant bioassay technique. Here, the weed was grown in mud pots and the herbicides were sprayed when the weed was in the vegetative phase. Among post emergence herbicides tested, best control was obtained for azimsulfuron followed by cyhalofop butyl and fenoxaprop p- ethyl. The weed was susceptible to these chemicals. In the case of bispyribac sodium and penoxsulam though initial control was observed, regrowth was seen after two weeks and so the chemical was classified as moderately resistant to the weed. The weed was resistant to pyrazosulfuron, where no drying symptoms were observed. All the four non-traditional rice herbicides tested viz., glyphosate, diuron, paraquat and glufosinate ammonium gave excellent control of I. miliacea and no regrowth was observed after two weeks
Open Access
Morpho-physiological changes in rice due to application of selected post emergent herbicides
(Department of Plant Physiology, College of Horticulture, Vellanikara, 2014) Ramanarayana, C V; KAU; Girija, T
The study on “Morpho-physiological changes in rice due to application of selected post emergent herbicides” was conducted during 2013-2014 at Alappad kole lands in farmer’s field. The objective of the experiment was to study the morphological, physiological and biochemical changes in rice due to application of Acetyl CoA carboxylase and Acetolactate synthase enzyme inhibitors and their effect on growth and yield of rice. The experiment was laid out in RBD with four replications and there were seven treatments comprising of three Acetyl CoA carboxylase enzyme inhibitors viz., Cyhalofop butyl, Fenoxaprop -p- ethyl and Metamifop and three Acetolactate synthase enzyme inhibitors viz., Bispyribac sodium, Azimsulfuron and Almix with Hand weeded as control. Herbicides were sprayed on 15 DAS. Observations on morphological, physiological, biochemical, yield attributes and yield of rice were recorded. Biochemical estimations were done on 7 days after herbicide application and at the time of flowering. Morphological characters were studied at 15 days interval. Herbicide application resulted in a two to four percent reduction in height and one to six percent reduction in tiller number of rice plant at harvest as compared to plants in the Hand weeded plot. Effect of herbicides on growth attributes viz., RGR, CGR and NAR indicated that at the initial and final stages of growth there was no significant difference between the treatments. However during the critical stages of growth i.e., 45-75 DAS significant variation was seen. Among the herbicide treatments, Bispyribac sodium.followed by Cyhalofob butyl applied plots had higher values as compared to the other herbicides. Azimsulfuron applied plots had the lowest value for these parameters. Among the growth indices LAI showed significant reduction irrespective of the herbicide throughout the growth stages as compared to Hand weeded control. The biochemical parameters such as nitrate reductase enzyme activity, phenol content, total soluble protein content and total amino acid content showed an initial decline when estimated one week after application of herbicide but by the time of flowering all the herbicide treated plants showed recovery. However the recovery was higher for Bispyribac sodium in the ALS inhibiting group and Cyhalofop in the ACCase inhibiting group. Proline content and catalase enzyme activity showed increase with herbicide application as compared to Hand weeded control indicating that application of these chemicals may be imparting stress to the plant, however by flowering time in most of the treatments there was recovery. Among the treatments, plants in the Almix and Azimsulfuron applied plots showed less recovery. The physiological parameters such as chlorophyll content, photosynthetic rate, stomatal conductance and IAA content showed decline when estimated one week after herbicide application. . In the case of chlorophyll content the recovery of the plant was comparatively less as compared to all other chemical constituents. Azimsufuron and Almix application contributed to maximum reduction in these constituents. Weed count and weed dry weight was taken on 60 DAS. The lowest values were recorded in Bispyribac sodium treatment. Azimsulfuron also a broad spectrum herbicide, was found less effective in the present study compared to Bispyribac sodium. In the present study, 5 to 17 percent reduction in grain yield and 6 to 17 percent reduction in straw yield of rice was observed by herbicide application. Among the ALS enzyme inhibitors, the lowest reduction in grain and straw yield was observed in Bispyribac sodium treatment and maximum reduction was in Azimsulfuron treatment. Among the ACCase enzyme inhibitors, Cyhalofop butyl showed least reduction in grain and straw yield of rice while fenoxaprop showed maximum reduction.
Open Access
Physiological, anatomical and molecular analysis of coconut palms (Cocos nucifera L.) affected with yellowing.
(Department of Plant Physiology,College of Agriculture, Vellayani, 2011) Deepa, S; KAU; Manju, R V
Kerala the ‘Land of coconut’ occupies first position in area and production of coconut in India but the productivity is below the national average. This is because of unproductive and senile palms, lack of adaptation of recommended cultivation practises and serious incidence of pests and diseases. The root (wilt), an endemic disease of Kerala causes an annual loss of 968 million nuts. Recently another type of yellowing characterised by mid whorl yellowing shedding of immature nuts and drying of inflorescence without showing characteristic ribbing symptom is rapidly spreading in many parts of Kerala. There is no research report available in this emerging problem in the coconut growing tracts of Kerala. Since there is rampant spreading of yellowing to other coconut cultivated areas causing a serious reduction in nut yield, this problem demands immediate attention. Hence an experiment was conducted in the Department of Plant Physiology, College of Agriculture, Vellyani to generate the basic information on the causative agents and on the changes of physiological, molecular and anatomical realms of coconut affected by mid whorl yellowing. A wide variation was observed in the physiological parameters like total pigments, relative water content, carbohydrate fractions, proteins, phenols and antioxidants betweenpalms with yellowing and control palms. The palms with yellowing showed a significant reduction in the total chlorophyll, chlorophyll a, chlorophyll b and carotenoid content when compared to the healthy palm. Relative water content was lower for all the palms with yellowing compared to the control palm and the healthy palms were maintaining a better water status and membrane integrity. All the selected palms with yellowing recorded an accumulation of reducing sugars compared to the healthy palms. The trend was similar for starch content except for palms with general yellowing. The control palms recorded maximum protein content compared to other palms with yellowing. A significant increase in the phenolic compounds was observed in palms with yellowing compared to the healthy palms. This results point to an activated defense system. The 14th leaf starting from the first fully opened one is the most widely used leaf for nutrient analysis as recommended by the IRHO. (Fremond et al., 1966).The 14th leaf data from the control palms and palms with different types of yellowing were analysed. The data showed that there were significant reductions in the levels of major nutrient nitrogen, phosphorus and also in the levels of magnesium and the micronutrient manganese in case of palms showing mid whorl yellowing compared to the control palm. But significantly higher levels of accumulation were found in case of potassium, calcium, iron and copper. These variations in the nutrient levels can have an influence on symptom development in coconut palms. The maximum yield was recorded for the control palm. Chlorophyll degradation and loss of structural integrity were evident from the anatomical studies of leaf tissues in case of palms with yellowing. Vascular browning which extended to the cortex and the vascular disintegration in the roots of affected palms were seen on anatomical analyses. A pure quality DNA was obtained by modified CTAB DNA isolation protocol. Molecular analyses using nested PCR showed that with the phytoplasma specific universal primers P1/P7-R16F2n/R16R2 provided an amplicon ) in the positive control and palms with inner and middle whorl yellowing and the primers R16mF2 /R16mR1 -R16F2n/ R16R2 provided an amplicon for the positive control and palms with inner, middle and general yellowing. The root (wilt) phytoplasma specific semi- nested primers IF7/7R3- IF7/7R2 provided an amplicon of 493 bp only for the positive control and no amplification was seen in any of the selected palms. The control palm and the palms affected with outer whorl yellowing provided no amplification at all for any of the primers tested. Amplification of phytoplasma specific universal primers in palms with mid whorl yellowing indicates that phytoplasma has got a role in development of the specific symptom. This demands immediate attention and extensive studies on the etiology, changes in biochemical profile, anatomy etc. Salient Findings Amplification of phytoplasma specific universal primers in palms with mid whorl yellowing indicates that phytoplasma has got a role in development of the mid whorl yellowing symptom. But in case of the root (wilt) phytoplasma specific primers, there was no amplification in palms with mid whorl yellowing. This suggests that the mid whorl yellowing of coconut palm which is an emerging problem in Kerala may not be associated with the root (wilt) disease. The results of biochemical and physiological analyses of the selected palms clearly indicate an altered primary metabolism, source-sink relation and a complexity in the nutriophysiology. These altered conditions can act as predisposing factors for the development of specific symptoms. The anatomical analyses showed damages of roots in the palms with mid whorl yellowing. They will have internal browning of vascular elements, extending into the cortex and also disintegration of vascular elements. Future line of work Detailed analysis of nutriophysiology, source-sink relation and hormonal profile. Studies on soil factors like nutrient level and water status. Extension of anatomical studies to different type of tissues. Extension of molecular studies into identification of specific phytoplasmal strains associated with mid whorl yellowing of coconut palms. Development of management strategy for the improvement of the field performance and productivity of coconut palms with mid whorl yellowing.

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