Different Agro-climatic Zones Of India Research Articles

Safety evaluation of flubendiamide and its metabolites on cabbage and persistence in soil in different agroclimatic zones of India

Supervised field trials following good agricultural practices were conducted at the research farms of four agricultural universities located at four different agroclimatic zones of India to evaluate the persistence and dissipation of flubendiamide and its metabolite, des-iodo flubendiamide, on cabbage. Two spray applications of flubendiamide 480 SC of standard and double dose at the rate of 24 and 48 g a.i. ha(-1) were given to the crop at a 15-day interval, and the residues of flubendiamide 2 h after spray were found in the range of 0.107-0.33 and 0.20-0.49 mg kg(-1) at respective doses. Residue of des-iodo flubendiamide was not detected in any cabbage sample during study period. No residues were found in the soil samples collected from all treated fields after 15 days of application. On the basis of data generated under All India Network Project on Pesticide Residues, a preharvest interval (PHI) of 10 days has been recommended, and the flubendiamide 480 SC has been registered for its use on cabbage by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India. The maximum residue limit (MRL) of flubendiamide on cabbage has been fixed by the Ministry of Health and Family Welfare, Government of India, under Food Safety Standard Authority of India as 0.05 μg/g after its risk assessment.

The Effect of Ambient Temperature on Some Biochemical Profiles of Black Bengal Goats (Capra aegagrushircus) In Two Different Agro-Climatic Zones in West Bengal, India

Being a multipurpose animal goat can produce meat, milk and hide. India has a good number of Black Bengal goat populations, which has an important role in the lives of local goat rearers. The goal of the present study is to find out the effects of changing seasons on some biochemical parameters ofBlack Bengal goat (Capra aegagrushircus) in two different agro-climatic zones in India. The highest mean value of temperature (42.6 ± 1.5 oC) has been reported during the month of April or May in the season of pre-monsoon in Purulia. However, the lowest value of temperature (8.6 ± 0.9 oC) has been reported during the month of December or January in the season of post-monsoon again in Purulia. The parameter studied here are blood pH, blood glucose level, concentration of Hb, RBC count, PCV, MCV, MCH and MCHC. Data has analyzed for the effect of seasonal variation among in both the regions and the current findings implies that not only seasonal variation but the regional variation also influence the major biochemical responses of goats.

Evaluation of Metalloenzymes as Biomarkers of Copper and Zinc Status in Sheep

Evaluation of Metalloenzymes as Biomarkers of Copper and Zinc Status in Sheep Copper (Cu) and zinc (Zn) deficiency is widespread in grazing ruminants throughout the world. Our recent survey indicated that Cu and Zn, among all the minerals, are most limiting trace minerals for livestock production in different agro-climatic zones of India. Copper and zinc play many significant roles in metabolism and is a component of several metalloenzymes and transcription factors. A severe form of deficiency in animals can readily be diagnosed from the combined evidence of the clinical and pathological lesions. However, diagnosis in the early stages or milder forms presents difficulties. There are several effective ways to diagnose Cu and Zn deficiency; however, each poses unique challenges

Cowpea [Vigna unguiculata(L.) walp.] seed proteins: Heterogeneity in total proteins and protein fractions

Eleven genotypes of V. unguiculata were screened for variability in total proteins and various protein fractions viz. albumins, globulins, prolamins and glutelins by using SDS-polyacrylamide gel electrophoresis. The electrophoretic pattern showed the molecular heterogeneity among total proteins as well as various protein fractions. The molecular weights of protein bands obtained by SDS-PAGE varied between 10 to 141.3, 15.85 to 147.9, 10 to 125.9, 7.94 to 56.23 and 10 to 79.43 kDa for total proteins, albumins, globulins, prolamins and glutelins, respectively. Most of the bands were common to the different genotypes indicating their close relationship with one another. However, a few bands unique to some particular genotypes were also observed showing the varietal differences. Cluster analysis based on total proteins and various protein fractions provided evidence for differences among the varieties collected from different agroclimatic zones of India. The observations revealed that seed protein polymorphism provides a useful information regarding variability among genotypes under investigation which could be helpful for breeding purposes in the improvement of protein quality and quantity in grain legumes.

Assessment of Genetic Diversity in Taro Using Morphometrics

Taro is an important tropical tuber crop, used as a staple food or subsistence food by millions of people in the developing countries. A program was done to analyze and identify the same promising 20 selected local and Indian accessions taro, aiming at the characterization of the extent and distribution of genetic diversity using morphological marker with the define objectives ‘to find genetic variability amongst the 20 taro genotypes collected from different agro-climatic zones in India, in respect of plant physical (like length of main sucker, no of petioles, length of leaf lamina, wt. of side tuber, number of side tuber, estimated Corm yield, breadth of leaf lamina)’. The present study revealed that the genetic diversity recorded through physical parameters corresponded with the genetic diversity revealed through molecular data analysis. On the basis of D2 statistics the 20 genotypes were grouped into six different clusters (I-VI). Most of the local taro genotypes collected from different locations (BCC-1, BCC-2, BCC10, BCC15, BCC18, BCC-21, BCC24 and BCC-25) were placed in Cluster II with moderate intra cluster distance indicating their closeness, and showed similar phenotypic characters. The genotypes viz. FC-4, FC-11 and PKS-1 were found to distantly relate to other genotypes and were grouped into Cluster III.

Evaluación de la diversidad genética en genotipos de Brassica juncea (Brassicaceae) utilizando diferencias fenotípicas y marcadores SSR

Brassica mustard species represent one of the most important oilseed crops in India, nevertheless, their genetic diversity is barely known. A better understanding on this topic is essential for the proper utilization of genotypes in breeding programmes. We evaluated the genetic diversity among 44 Indian mustard (Brassica juncea) genotypes including varieties/purelines from different agro-climatic zones of India and few exotic genotypes (Australia, Poland and China). For this, we used A and B genome specific SSR markers and phenotypic data on 12 yield and yield contributing traits. Out of the 143 primers tested, 134 reported polymorphism and a total of 355 alleles were amplified. Dendrograms based on Jaccard's similarity coefficients and Manhattan dissimilarity coefficients were generated based on an average linkage algorithm (UPGMA) using marker data and phenotypic data. Genotypes were grouped into four clusters based on genetic distances. Both the clustering patterns based on Jaccard's similarity and Manhattan dissimilarity coefficients, independently, discriminated the genotypes effectively as per their pedigree and origin. PCoA revealed that, the grouping of genotypes based on SSR marker data is more convincing than phenotypic data, however, the correlation between phenotypic and genetic distance matrices was observed to be very low (r = 0.11). Hence, for diversity studies reliability on molecular markers is worth proving and SSR markers are the stronger tools than quantitative traits in discriminating B. juncea genotypes.

Bio-control activity of Purpureocillium lilacinum strains in managing root-knot disease of tomato caused by Meloidogyne incognita

The potential of 24 indigenous isolates of Purpureocillium lilacinum (Paecilomyces lilacinus) (Thom) Samson collected from different agro-climatic zones of India was investigated against the root-knot nematode, Meloidogyne incognita. The studies were conducted in vitro (larvicidal, ovicidal and egg-parasitising capacity) and under naturally infested field conditions with selected strains. Repeated field trials were conducted with talc-based preparations of fungal strains at 10 kg ha−1, which were applied mixed in farm yard manure (FYM) at 1.5 t ha−1. Results (in vitro) showed that all tested isolates were capable to parasitise eggs, inhibit egg hatching and cause juvenile mortality of M. incognita at various levels. Based on the performance under in vitro studies, eight isolates (NDPL-01, ANDPL-02, SHGPL-03, HYBPL-04, AHDPL-05, PTNPL-06, SNGPL-07 and VNSPL-08) were re-tested to confirm the results. HYBDPL-04 was found causing highest mortality (80%), inhibition of egg hatching (90%) as well as parasitisation of M. incognita eggs (75%). Under field trials also, the best protection of root-knot disease of tomato (Lycopersicon esculentum L.), in terms of reduction of galls (61%) and reproductive factor (Pf/Pi (RF) = 0.2) was achieved through application of HYBDPL-04 + FYM compared to control and other tested isolates. It also enhanced marketable yield of tomato up to 43%. It is concluded that the HYBDPL-04 strain of P. lilacinum is highly effective for management of root-knot disease of tomato under naturally infested field conditions. It is the isolate which produced the maximum number of metabolites which were extracted through high pressure liquid chromatography.

Molecular characterization of vernalization and photoperiod genes in wheat varieties from different agro-climatic zones of India

Ninety-nine wheat cultivars from six different agro-climatic zones of India were analyzed for the Vrn-1, Vrn-2, Vrn-B3, Vrn-4 and Ppd-D1 composition with DNA sequenced based allele specific or linked markers for the above-mentioned genes. A majority of the germplasm carried the dominant Vrn-A1a allele alone or in combination with Vrn-B1 and Vrn-D1. The three dominant genes were cumulatively present in 30 cultivars among all the zones, whereas double dominant combination, Vrn- A1/Vrn-B1 was identified in 18 cultivars, Vrn-A1/Vrn-D1 in 6 cvs and Vrn-B1/Vrn-D1 in 16 cvs. The combination of the dominant alleles of all three genes was most frequent in cvs of Northern Western Plains Zone. Northern Hill Zone had vrn-B1 and vrn-D1 alleles in higher proportions compared to the dominant alleles Vrn-B1 and Vrn-D1 indicating successful spring/winter wheat cross breeding. All of the cvs had the recessive Vrn-B3 allele. Most of the cvs had photoperiod insensitive allele in all the zones and only 9% cvs possessed the photoperiod sensitive allele (b) of the Ppd-D1 gene. This information will be useful in selecting parental lines for crossing to maximize diversity at these loci and for future molecular marker assisted breeding for cultivar improvement.

Intra population diversity in Rhizocotonia bataticola causing dry root rot of chickpea (Cicer arietinum L.) in India

Fifty isolates of dry root rot pathogen Rhizoctonia bataticola collected from different agro-climatic zones in India were evaluated for the degree of subdivision in isolates level. The isolates showed variability in pathogenicity test. Genetic characteristics were analyzed based on the sequence of the rDNA-internal transcribed spacer (ITS) region. The phylogenetic tree based on rDNA-ITS analysis showed that the maximum number of R. bataticola isolates were very diverse and did not depend on geographical origin. Both pathological and molecular data correlated each other and supported that the R. bataticola present in India were very diverse and independent to their origin.

Improved CN-Based Long-Term Hydrologic Simulation Model

Employing the advanced soil moisture accounting (ASMA) procedure and the modified subsurface drainage flow concept, a curve number (CN)–based model, named as modified long-term hydrologic simulation advance soil moisture accounting (MLTHS ASMA) model, is proposed to simulate daily flows. Its application to 17 watersheds falling in different agro-climatic zones of India and comparison with the existing long-term hydrologic simulation advance soil moisture accounting (LTHS ASMA) model reveal that the proposed model yields higher efficiency, lower standard error of estimate (SE) and percentage relative error (RE) values for high runoff producing wet watersheds, and lower efficiency for low runoff producing dry watersheds, indicating a very good model response to wet watersheds, and good to satisfactory-to-dry watersheds. On most watersheds, the proposed model performed better than the existing one. In addition, CN parameters for surface and subsurface flows were most sensitive followed by the parameters related with soil characteristics, and the significance of base flow was greater in wet watersheds than in dry watersheds.

Assessment of flubendiamide residues in pigeon pea in different agro-climatic zones of India

Supervised field trials were conducted at the research farms of four agricultural universities located at different agro-climatic zones of India to find out the harvest time residues of flubendiamide and its des-iodo metabolite on pigeon pea (Cajanus cajan) during the year 2006-2007. Two spray applications of flubendiamide 20 WDG at 50 g (T(1)) and 100 g (T(2)) a.i./ha were given to the crop at 15-days interval. The foliage samples at different time intervals were drawn at only one location, however, the harvest time samples of pigeon pea grain, shell, and straw were drawn at all the four locations. The residues were estimated by HPLC coupled with UV-VIS variable detector. No residues of flubendiamide and its des-iodo metabolite were found at harvest of the crop at or above the LOQ level of 0.05 μg/g. On the basis of the data generated, a pre-harvest interval (PHI) of 28 days has been recommended and the flubendiamide 20 WDG has been registered for use on pigeon pea by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India and the MRL has been fixed by Ministry of Health and Family Welfare, Government of India under Prevention of Food and Adulteration as 0.05 μg/g on pigeon pea grains.

Spatio-temporal Trends of Standardized Precipitation Index for Meteorological Drought Analysis across Agroclimatic Zones of India

Abstract1. Introduction:Drought is a normal part of climate of India and every year it affects one or the other State. Droughts, like other meteorological phenomena, have spatial and temporal characteristics that vary significantly from one region to another. The understanding of the spatio-temporal trends of meteorological drought helps in undertaking informed decisions on their preparedness and mitigation measures. Though no significant trends have been reported in the Indian Summer Monsoon Rainfall (IMSR) over long periods, the spatio-temporal trends in drought indices reveals the anomaly in rainfall across regions over different time scales which may be related to climate change induced extreme rainfall events. So, a study was carried out to compute spatio-temporal trends in Standardized Precipitation Index (SPI), an index of rainfall anomaly, using gridded monthly rainfall datasets of CRU TS 3.0 for the 1951 – 2006 period for Indian landmass and the results are reported here.2. Methodology:SPI is simply the difference in standardized precipitation from its mean for a specified time period divided by the standard deviation. As precipitation is typically not normally distributed for accumulation periods of 12 months or less, SPI overcomes this disadvantage by fitting an incomplete gamma distribution and then transforming it to normal distribution. Negative values of SPI due to less than normal rainfall indicate dryness while SPI less than -1 indicate drought. Delineation of homogeneous regions for climate change / trend analysis has been a debatable matter due to unwise delineation of the homogeneous regions based on a single climatic variable, mostly the isohyets. Therefore, in this study 14 Agroclimatic Zones (ACZs) of India were selected for SPI trend analysis as homogeneous regions (Fig 1) due to commonality of climatic parameters and their extremes, soil types and water resources. The results of drought trends at ACZ level also can be directly translated into plans for agricultural sectors. SPI were computed for individual months (June, July, August and September) and for the whole Indian summer monsoon duration (June-July-August-September i.e. JJAS). Mean SPIs of various ACZs for the individual months and JJAS over a 56 year period were analyzed for temporal trends using the Mann Kendall test and regional temporal trends across all ACZ together using the Regional Kendall test.3. Results: Significant temporal trends in monthly & JJAS SPI at 10% or lower level of significance were observed for ACZ4 (Middle Gangetic plains), ACZ5 (Upper Gangetic plains), ACZ6 (Trans Gangetic plains), ACZ7 (Eastern plateau and hills), ACZ8 (Central plateau and hills), ACZ12 (West coast) and ACZ14 (Western dry) regions. The rest of the ACZs did not show any significant trend in SPI for the 56 year study period. In ACZ4, SPI showed a consistently negative trend for JUN, JUL, AUG and JJAS, whereas in ACZ5, SPI showed a significant negative trend for JUL, AUG & JJAS. SPI showed a significant negative trend in SEP & JJAS for ACZ7, AUG & JJAS in ACZ8, JUL in ACZ12 and AUG in ACZ14. On the other hand, a significantly positive trend in SPI was observed in JUN in ACZ6, ACZ8, and ACZ12.The analysis of temporal trends in SPI for all ACZs taken together using the Regional Kendall test showed a significant positive trend in JUN SPI, while significant negative trends in SPI were observed for JUL, AUG and JJAS across India. No significant trend was observed for SEP SPI. The rate of increase in JUN SPI was 0.75E-02 per year, while the rate of change of SPI for JUL, AUG, & JJAS was -0.76E-02, -0.54E-02, and -0.65E-02 per year, respectively.4. Conclusions: Among the different ACZ of India, there was an increase in probability of meteorological drought hazard in ACZ4, ACZ5, ACZ7 and ACZ8 covering the States of Bihar, Uttar Pradesh, Madhya Pradesh, Orissa and Eastern Rajasthan. Results also point to a significant decreasing trend in rainfall in these regions for different months as well as for the JJAS monsoon period. In the dry western parts of India (Western Rajasthan and Gujarat), which are traditionally water scare regions, there is no change in probability of occurrence of meteorological drought.For India as a whole, there is an increase in probability of meteorological drought in the future due to decreasing trends in rainfall for the JJAS period. The months of July and August will become drier, while June will become wetter. This change in rainfall distribution towards the early period and overall drier months of July and August have an important implication for the productivity of the main crop season of India thus impacting its food security negatively.

Genetic characterization of mango anthracnose pathogen Colletotrichum gloeosporioides Penz. by random amplified polymorphic DNA analysis

Twenty-five isolates of Colletotrichum gloeosporioides causing mango anthracnose were collected from different agroclimatic zones of India. The isolates were evaluated for their pathogenic variability on mango seedlings and genetic characterization using random amplified polymorphic DNA (RAPD molecular techniques). The random primers OPA-1, 3, 5, 9, 11, 15, 16 and 18 were used and the twenty-five isolates were grouped into two. The amplified DNA fragments (amplicons) obtained was compared by agarose gel electrophoresis. Isolate specific RAPD fingerprints were obtained. Out of eight primers in RAPD, OPA-1, 3 and 18 were able to produce reproducible banding pattern. Each of these primers generated a short spectrum of amplicons, located between 661 and 2291-bp markers, indicative of genetic polymorphism. Dendogram revealed more than 75% level of similarity. 4.36% polymorphism was also found in individual isolates that was not statistically significant (P > 0.05) among the sample, it also indicates that all the isolates tested had approximately same genetic identity. The data suggest that RAPD may be of value by virtue of its rapidity, efficiency and reproducibility in generating genetic fingerprints of C. gloeosporioides isolates. Key words: Colletotrichum gloeosporioides, genetic identification, mango anthracnose.

Genetic Variability on Growth, Phenological and Seed Characteristics of Jatropha curcas L.

Twenty randomly selected seeds of Jatropha curcas collected from different agroclimatic zones of India were studied for variability on growth, phenology and seed characteristics in a progeny trial under tropical monsoon climatic conditions of Bhubaneswar (200 14’N/850 50’ E), India. Correlation studies revealed that length and number of branches were positively correlated with the number of inflorescence (P<1%) and number of fruits per plant (P<5%). A positive correlation between fruit diameter and oil content and also, between seed length and test weight was observed. Number of fruits per plant showed almost 100% heritability followed by the number of inflorescence (88.79%). Non hierarchical Euclidean cluster analysis resulted in six clusters with highest number of six accessions namely, ‘Chandaka’, ‘PKVJ-AKT-1’, ‘TNMC-4’, ‘PKVJ-MKU-1’, ‘TFRI-1’ and Indore falling under cluster II. Maximum and minimum intracluster distances were observed for cluster II (2.929) and cluster III (0.000), respectively. Maximum inter-cluster distance (7.195) was found between cluster III and VI followed by Cluster III and IV (7.074). Analysis of the results of the present study clearly indicate that crossing between the accessions of cluster III and VI would be useful in developing variable genotypes in the subsequent generations.

Efficient plant regeneration from immature embryo cultures of Jatropha curcas, a biodiesel plant

Jatropha curcas L. (Physic nut) is a commercially important non-edible oil seed crop known for its use as an alternate source of biodiesel. In order to investigate the morphogenic potential of immature embryo, explants from four developmental stages were cultured on medium supplemented with combinations of auxins and cytokinins. It was found that the size of embryo is critical for the establishment of callus. Immature embryos (1.1–1.5 cm) obtained from the fruits 6 weeks after pollination showed a good response of morphogenic callus induction (85.7%) and subsequent plant regeneration (70%) with the maximum number of plantlets (4.7/explant) on Murashige and Skoog’s (MS) medium supplemented with IBA (0.5 mg l−1) and BA (1.0 mg l−1). The above medium when supplemented with growth adjuvants such as 100 mg l−1 casein hydrolysate + 200 mg l−1l-glutamine + 8.0 mg l−1 CuSO4 resulted in an even higher frequency of callus induction (100%). Plant regeneration (90%) with the maximum number of plantlets (10/explant) was achieved on MS medium supplemented with 500 mg l−1 polyvinyl pyrrolidone + 30 mg l−1 citric acid + 1 mg l−1 BA + 0.5 mg l−1 Kn + 0.25 mg l−1 IBA. It was observed that plantlet regeneration could occur either through organogenesis of morphogenic callus or via multiplication of pre-existing meristem in immature embryos. The age of immature embryos and addition of a combination of growth adjuvants to the culture medium appear to be critical for obtaining high regeneration rates. Well-developed shoots rooted on half-strength MS medium supplemented with 0.5 mg l−1 IBA and 342 mg l−1 trehalose. The rooted plants after acclimatization were successfully transferred to the field in different agro-climatic zones in India. This protocol has been successfully evaluated on five elite lines of J. curcas.

Persistence and Transformation of Thiamethoxam, a Neonicotinoid Insecticide, in Soil of Different Agroclimatic Zones of India

Persistence and Transformation of Thiamethoxam, a Neonicotinoid Insecticide, in Soil of Different Agroclimatic Zones of India

Variability in triterpenoids (nimbin and salanin) composition of neem among different provenances of India

Azadirachta indica A. Juss. (Neem) is a source of several bioactive triterpenoids, however, only azadirachtins have been commercially exploited. Salanin and nimbin are the other major active potential bioactive compounds that can be used for product development as well as markers for selection and improvement of neem. Thirty-three provenances, and individual trees from three locations from different agro-climatic zones of India were examined to assess quantitative variations. Nimbin and salanin were quantified using RP-analytical HPLC. Elite individuals with exceptionally higher salanin and nimbin content were identified. There were wide variations in seed area, oil content, nimbin and salanin concentrations among different provenances and also between individual trees of a particular provenance. Nimbin concentration ranged from 18.2 to 636.8 mg kg −1, whereas salanin was in the range of 45.4–1830.3 mg kg −1 kernel weight. Analysis of variance for seed area, oil content, nimbin and salanin among various neem provenances showed significant differences in oil content, nimbin and salanin. Correlation coefficients among the parameters investigated showed nimbin and salanin as significantly correlated. Nimbin and salanin content also varied between individual trees of a particular location. The study shows that nimbin or salanin synthesis did not appear to be influenced by environmental conditions as individual trees from the same agro-climatic zone showed different trends. It can be concluded that there are individual genetic differences among neem trees. This provides an ample scope for tree improvement by half-sib progeny trials followed by clonal propagation.

Status of some economically Important under-Exploited medicinal Plant species in the Uttaranchal hills

Keeping in view the protection and conservation of the bio-diversity and related indigenous systems of medicines, the Indian Science of Medicines and Homeopathy (ISM &amp; H) Department under the umbrella of the Ministry of Health and Family Welfare has identified and recognised 136 under-exploited plant species of medicinal value which are being used in Ayurveda, Sidha and Homeopathy. These plant species have been allocated to 34 different institutes/state agricultural universities (SAUs) organizations situated in different agro-climatic zones of India for the development of agro-techniques for wider cultivation in order to save conservation and make available raw material to the industry/indentors/users. The National Bureau of Plant Genetic Resources (NBPGR), New Delhi and its 3 regional stations, i.e., Bhowali, Shillong and Shimla have been allocated 20 plant species. The Bhowali station has been assigned 5 plant species, i.e., Callicarpa macrophylla, Curcuma zedoaria, Piper retrofractum, Pistacia integerrima and Quercus infectoria for the inventory of agro-techniques. The present paper highlights the status of these plant species and observation on their growth behaviour, performance and adaptability in the study area.

Low levels of genetic diversity detected by RAPD analysis in geographically distinct accessions of Bacopa monnieri

Brahmi (Bacopa monnieri) is atraditional Indian medicinal plant known for its natural nootropicaction of saponins present in large amount in its shoots. Acollection of 24 B.monnieri accessions from differentagro-climatic zones of India and an introduction from Malaysiamaintained in the field genebank at CIMAP was analysed for RAPDvariation. Among the 40 random primers tested, 29 primers generatedone or more polymorphic bands. The number of polymorphic bandsgenerated was primer dependent, ranging from 2 to maximum of 8.Similarity matrices were generated from the RAPD data on the basis ofNei's estimates of similarity indices and dendrograms wereconstructed based on UPGMA clustering. All the accessions were foundto be in the range of 0.8–1.0 of similarity, which isindicative of a narrow genetic base among the various accessions witha medium level of polymorphism. It was possible to differentiateindividual accessions, showing differences in morphological andgrowth properties at DNA level. The observed low levels of geneticvariation were attributed to interplay of sexual and vegetative modesof reproduction and similarity of local environments in habitats ofB. monnieri.

Clonal variation in temperature response of photosynthesis in tea

The effect of temperature on the photosynthetic characteristics of six tea clones (viz., 6017, B/5/63, B/6/61, B/6/62, CCS-26 and T-78), originally from different agro-climatic zones in India, was studied to determine the clonal variation in photosynthesis, if any. The results clearly indicated significant clonal differences in relation to temperature. Of the six clones, B/5/63 and B/6/61 were found to be relatively thermotolerant. Both stomatal and mesophyll components seemed to be responsible for the differences in temperature dependence of photosynthesis, however, their magnitude varied with the tea clones. Differences in water use efficiency were also observed between clones. However, differences became less pronounced at the higher temperature. Clone B/5/63 showed higher water use efficiency and lower values for stomatal conductance and transpiration. Thus this clone may be suitable for relatively dry and exposed sites. A 2–10-fold increase in dark respiration with increase in temperature was also observed. However, higher increase was associated with clones having higher photosynthetic rates, indicating an association between photosynthetic and respiratory rates. The results provide a valuable indication regarding clonal variation in temperature responses of photosynthesis and may be used to offer useful suggestions to tea growers in the initial selection of tea clones.