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Open Access
RESPONSE OF BLACK GRAM GENOTYPES TO PLANT GROWTH REGULATORS UNDER LATE SOWN CONDITIONS
(AAU, Jorhat, 2018-07) Baishya, Navanita; Kalita, Prakash
A pot experiment was carried out during the kharif season of 2017 with five black gram genotypes in the stress physiology premises of Department of Crop Physiology, AAU, Jorhat-13. Five black gram genotypes viz., LBG-752, PU-30, PU-40, AZAD URD-3 and LBG-645 were sown at three different dates viz., 15th September (recommended date of sowing i.e. D1), 1st October (15 days delayed beyond recommended date of sowing i.e. D2), and 15th October (30 days delayed beyond recommended date of sowing i.e. D3) and were treated with water spray (control), 50 ppm GA3 and 500 μ mole/lit salicylic acid at 20 DAS and 15 days there after. The objectives of the experiment was to evaluate the physiological performance of black gram genotypes under late sown situation and to examine the influence of some plant growth regulators in improving productivity of black gram genotypes under late sown conditions .Significant variations were recorded due to the genotypes, treatments (plant growth regulators) as well as dates of sowing in terms of various parameters namely leaf area, leaf number, plant height, root volume, root surface area, root length, number of nodules, whole plant biomass, leaf total chlorophyll content, in vivo leaf nitrate reductase activity, lipid peroxidase activity, proline content, number of pods per plant, number of seeds per pod, seed yield and harvest index. The interaction between genotypes and growth regulator treatments was also found to be significant for these traits. The genotypes responded differently towards the dates of sowing for the traits namely leaf area, plant height, root volume, root surface area, whole plant biomass, total chlorophyll content, lipid peroxidase activity, hundred seed weight and seed yield and the interaction among genotypes, plant growth regulators and sowing dates was found to be significant in terms of plant biomass content at harvest. In general, all the traits excepting lipid peroxidase activity exhibited a declining trend with delayed dates of sowing compared to that of recommended date of sowing. The genotype LBG-645 showed the best yield performance followed by AZAD URD-3 when sowing was done in the recommended date as well as in delayed dates. On the other hand, the genotype PU-40 registered the lowest yield performance in both the situations. The GA3 treated plants showed the best performance for most of the traits as compared to salicylic acid treated plants and water spray under all the sowing dates. The combination of LBG-645 with GA3 treatment recorded the best results for most of the traits under all the three dates of sowing. In the case of the recommended date of sowing, the values of seed yield in LBG-645, AZAD URD-3 and PU-40 with GA3 treatment were 12.96 g plant-1, 10.39 g plant-1, 5.96 g plant-1 respectively. With second date of sowing (1st October) the corresponding seed yield values were 11.18 g plant-1, 7.04 g plant-1, 4.75 g plant-1 respectively. When the sowing was done on 15th October, the GA3 treated plants of LBG-645, AZAD URD-3 and PU-40 recorded 8.61 g plant-1, 4.53 g plant-1, 4.51 g plant-1 respectively. The higher values of grain yield in LBG-645 with applied GA3 may be related to its better performance for the traits namely leaf area, root surface area, whole plant biomass, leaf total chlorophyll content, in-vivo leaf nitrate reductase activity and harvest index. From the correlation study also positive and significant correlations were recorded in D1, D2 and D3; between seed yield and leaf area (0.770**, 0.695**, 0.727**), seed yield and root surface area (0.736*, 0.796**, 0.541**), seed yield and whole plant biomass (0.790**, 0.638**, 0.723**), seed yield and total leaf chlorophyll content (0.833**, 0.805**, 0.673**), seed yield and in-vivo leaf nitrate reductase activity (0.813**, 0.784**, 0.705**), seed yield and harvest index (0.983**, 0.083**, 0.987**).
Open Access
MORPHO-PHYSIOLOGICAL PERFORMANCE OF SOME LENTIL GENOTYPES IN RESPONSE TO ORGANIC MANURE SOURCES
(AAU, Jorhat, 2018-07) Borah, Horipriya; Kalita, P.
A field experiment was conducted during the rabi season of 2017-18 at ICR farm (organic block) of AAU, Jorhat-13. Five lentil genotypes were evaluated for their morpho-physiological performance in response to three different sources of organic manure. The genotypes were HUL-57, SLC-102, SLC-101, KLS-218 and PL-406 which were collected from Regional Agricultural Research Station, AAU, Shillongani, Nagaon and the souces of organic manure were FYM, vermicompost and poultry manure. The recommended package of practices for lentil under Assam situation were followed for raising the crop . The recomended levels of N, P and K were supplied with various organic manure sources. Significant variations were recorded among the genotypes as well as sources of organic manure at both the stages of observation in relation to the various traits viz plant height, leaf biomass, root biomass, whole plant biomass. The traits viz. root volume, root surface area, nodules number, stem biomass ,reproductive biomass, in-vivo leaf nitrate reductase activity, total chlorophyll content of leaf, lipid peroxidation, leaf nitrogen content, leaf phosphorus content showed significant variation due to genotypes as well as organic manure sources at active pod filling stage only. At harvest number of pods per plant, 100 grain weight, grain yield and harvest index also exhibited significant variation due to genotypes as well as sources of organic manure.The interaction between genotypes and manure sources were found to be significant for the traits viz leaflet number per plant for both the stages of observation and stem biomass at 50% flowering and leaf proline content at active pod filling stage. Highest values of these traits were recorded in the plants supplied with vermicompost followed by poultry manure and FYM except the trait of lipid peroxidase activity which showed just the opposite trend. The genotype KLS-218 with vermicompost treatment recorded the highest plant biomass and grain yield at harvest. This increase in grain yield was 9.1% and 6.8% with vermicompost over FYM and poultry manure respectively. The highest grain yield in KLS-218 may be attributed to the higher values in the traits like relative leaf water content, leaflet no per plant, nodule no per plant, leaf biomass, stem biomass, reproductive biomass, whole plant biomass, nitrate reductase activity, total leaf chlorophyll content, proline content, leaf nitrogen content, leaf phosphorus content, no of pods per plant, no of seeds per pod, 100 grain weight and harvest index. From the correlation study positive and significant correlation were recorded between seed yield and relative leaf water content (0.772**), seed yield and leaflet no at 50% flowering(0.887**), seed yield and leaflet no at active pod filling stage (0.790**, seed yield and nodule no (0.911**), seed yield and leaf biomass at 50%flowering (0.891**), seed yield and leaf biomass at active pod filling stage (0.854**), seed yield and stem biomass at 50%flowering (0.909**), seed yield and stem biomass at active pod filling stage (0.908**), seed yield and whole plant biomass at 50%flowering (0.935**), seed yield and whole plant biomass at active pod filling stage (0.967**), seed yield and reproductive biomass (0.924**), seed yield and nitrate reductase activity (0.883**), seed yield and total chlorophyll content (0.873**), seed yield and proline content (0.895**), seed yield and leaf nitrogen content (0.923**), seed yield and leaf phosphorus content (0.878**), seed yield and no of pods per plant(0.919**), seed yield and no of seeds per pod(0.892**), seed yield and 100 grain weight (0.907**) and seed yield and harvest index (0.979**). The genotype KLS-218 registered highest benifit cost ratio i.e 1.43, 1.52, 1.46 for FYM, vermicompost and poultry manure respectively and this genotype can be recomended for Assam condition with the supply of N,P and K through vermicompost.
Open Access
RESPONSES OF SOME WHEAT (Triticum aestivum L.) GENOTYPES TO AEROSOLS OF NITROGEN
(AAU, Jorhat, 2018-07) Borgohain, Eshani; Bharali, Bhagawan
Wheat (Triticum aestivum L.) is one of the most important cereal crops globally, and it is a staple food for about one third of the world’s population. Cultivation of wheat has been the symbolic of green revolution that played pivotal role in making the nation a food surplus nation. The importance of wheat in Indian Agriculture is second to rice. The investigation into the effects of Nitrogen aerosols on some wheat (Triticum aestivum L.) genotypes (viz., 306, 1544, LOK-1, SHRI RAM-273), was accomplished both under field (October, 2016-March, 2017) and pot culture (October, 2017-March, 2018) at ICR farm and at the vicinity of Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University, respectively. The main objective of the investigation was to evaluate the physiological traits in wheat fertilized with Nitrate aerosols under field condition. The study, too, looked into the action mechanism of Nitrogen aerosol altering the physiology of wheat crop, and the relations between economic yield, physiological attributes and nitrogen status of wheat crop under the influence of aerosols. Treatments were applied at three stages viz., seedling, maximum tillering and spike initiation stages. The aerosols @ 400 ppm (≈40 kg N ha-1), were applied in three times i.e. 1200ppm or 1.2% (on sunny days in the afternoon (after 2–3 P. M.) when air temperature was low. In the field experiment, at maximum tillering and spike initiation stages, almost all the Nitrogen aerosols as compared to control increased the parameters significantly in a range viz., leaf area (8-13%) and (6-15%), LAI(19-31%) and (25.08-31.43%), SLW (11-26%), tiller numbers (14-28%) and (16-24%), effective tillers (19-31%), plant height (3-6%), rate of Pn (9-19%) and(10-16%), total chlorophyll content (14-34%) and (19-31%), chlorophyll a content (16-45%) and (23-35%), chlorophyll b content (14-33%) and (17-29%), NR activity (12-25%) and (23-36%), lipid peroxidase (6-53%) and (2-9%), CMS (14-28%), total carbohydrate content (18-28%), N content in grains (18-37%), NUE (26-39%), intercellular [K+] (13-31%), exchangeable [K+] (14-32%), intercellular [Ca2+] (11-28%) and exchangeable [Ca2+] (8-17%). The aerosols also increased the yield attributes such as no. of seeds per spike (2-7%), length of spike (14-24%), spike weight (14-18%), test weight (4-10%), harvest index (1.23-5.38%), biological yield (2-3%) and economical yield (3-8%). However, CMS was reduced non-significantly as compared to control at spike initiation stage. In the pot experiment, too, as compared to control, almost all the Nitrogen aerosols increased the parameters significantly in a range at maximum tillering stage and at spike initiation stages, respectively viz., leaf area (8-14%) and (4-10%), LAI (11-25%) and (11-21%), SLW (11-20%), tiller numbers (12-21%) and (10.68-16.66%), effective tillers (14.83-21.25%), plant height (5-8%), rate of Pn (16.78-23.43%) and (18-24%), total chlorophyll content (22-39%) and (26-33%), chlorophyll a content (22-43%) and (34-41%), chlorophyll b content (22-37%) and (23-30%), NR activity (14-28%) and (7.39-14.26%), lipid peroxidase (4-16%) and (2-9%), CMS (12-42%) and (12-26%), total carbohydrate content (7-16%), N content in grains (18-39%), NUE (25-42%), intercellular [K+] (21-44%), exchangeable [K+] (8-18%), intercellular [Ca2+] (7-24%) and exchangeable [Ca2+] (11-21%) . The aerosols also increased the yield attributes such as no. of seeds per spike (2-6%), length of spike (12-22%), spike weight (7-15%), test weight (5-9%), harvest index (2-7%), biological yield (2-7%) and economical yield (6-11%). In the field experiment, the variety LOK-1 possessed the highest score (25) followed by SHRI RAM-273 (10), and 1544 and 306 (2) considering their responses to the aerosols at maximum tillering, spike initiation and harvest stages. In the pot experiment, the variety LOK-1 possessed the highest score (28) followed by 1544 (4), SHRI RAM-273 (3) and 306 (2). However, based on the overall performance of the varieties at field and pot experiments together, the variety LOK-1 possessed the highest score (53) followed by SHRI RAM-273 (13), 1544 (6) and 306 (4). Thus, it could be concluded that the variety LOK-1 emerged as the most physiologically efficient one in the experiments. The physiological characteristics supporting the holistic performance of the variety LOK-1 especially are higher leaf area (12.90 cm2 plant-1) and (16.92 cm2 plant-1), LAI (1.63) and (0.99), effective tillers (2.69) and (3.89), rate of net photosynthesis (8699.76 ppm CO2 absorbed g-1d.w.h-1) and (9042.73 ppm CO2 absorbed g-1d.w.h-1), total chlorophyll content (2.48 mg g-1 fw of leaf) and (2.59 mg g-1 fw of leaf), chlorophyll a content (0.73 mg g-1 fw of leaf) and (0.80 mg g-1 fw of leaf), chlorophyll b content(1.68mg g-1 fw of leaf) and (1.73 mg g-1 fw of leaf), nitrate reductase activity (17.21 nmol NO2- g-1 fw of leaf hr-1) and (33.16nmol NO2- g-1 fw of leaf hr-1), CMS (0.17) and (0.65), carbohydrate content (147.63 mg g-1 dw) and (144.84 mg g-1 dw), intercellular [K+] (0.98 mg g-1 fw) and (1.07 mg g-1 fw), exchangeable [K+] (2.03mg g-1 fw) and (1.97 mg g-1 fw), intercellular [Ca2+] (1.66 mg g-1 fw) and (1.61 mg g-1 fw), exchangeable [Ca2+] (8.28 mg g-1 fw) and (8.28 mg g-1 fw), length of spike (10.78 cm) and (11.02 cm), spike weight (1.63 g) and (1.83g), test weight(47.15 g) and (4.57g), harvest index(69.42) and (51.57), biological yield (1.43 t ha-1) and (10.13 g plant-1) and economical yield(0.99 t ha-1) and (5.23 g plant-1) for field and pot respectively. Further as regard to the field application of N aerosols, KNO3 scored the highest (26) followed by Ca(NO3)2 (7), NH4NO3 (5), Control (0) considering the overall scores at maximum tillering, spike initiation and harvest stages. Similarly, in the pot experiment, KNO3 scored the highest (23) followed by Ca(NO3)2 (10), NH4NO3 (4), Control (0). However, based on the overall performance of the varieties at field and pot experiments together, the treatment KNO3 scored the highest (49) followed by Ca(NO3)2 (17), NH4NO3 (9), CONTROL (0). The correlation studies revealed that seed yield in LOK-1 was positively correlated with length of spike (0.63*, 0.97**), spike weight (0.69*. 0.09), harvest index (0.88**, 0.74*), biological yield (0.89**, 0.94*) and N content (0.80**, 0.94**) both for field and pot experiments respectively. In case of aerosol treatments, KNO3 was positively correlated with length of spike (0.97**, 0.55), test weight (0.88**), harvest index (0.96**, 0.79*), biological yield (0.78*, 0.76*) and N content (0.93**, 0.79*) at P (0.05)/ and P (0.01).
Open Access
Germination, seedling survival, growth and development of rice (Oryza sativa L.) under anoxia
(AAU, Jorhat, 2018-07) Paul, Deepjyoti; Das, Ranjan
The experiment was conducted for two years during kharif season 2016 and 2017. One hundred and forty six rice genotypes from different ecotypes were collected and screened for submergence tolerance. Out of 146 genotypes, six genotypes viz. Ronga Lahi, Ronga Bao, Bangali Lahi, Suwag Moni Horu, Asra 123 and Asra 8 were selected as anoxia tolerant lines based on germination, survival and growth. After screening, the six genotypes were evaluated to understand the mechanism of tolerance from germination to seedling stage (plastic glasses in tray) and during vegetative and reproductive growth period (plastic pot) under submergence and normal condition in comparison to susceptible genotype IR 64. Significant variation was recorded during anoxic germination among the genotypes. Highest amylase activity viz., alpha amylase and beta amylase, total sugar, non structural carbohydrate was recorded higher in Asra 123 followed by Asra 8 as compared with susceptible genotype IR-64 indicating that sufficient amount of soluble sugar was produced immediately after imbibition due to significant increase of amylase activity at the time of germination particularly in highly tolerant genotypes. Lower stem elongation rate was recorded in genotypes Asra 123, Asra 8 followed by Ronga Lahi and Ronga Bao. This may be related with lower use and more conservation of carbohydrate during submergence to support growth and development after the water recedes. This may be an inherent character of such genotypes which may reflect even after seed formation and this is attributed in our present investigation where more amount of reserve in total soluble sugar were recorded in tolerant genotypes with higher amylase activity in first experiment. Stress induced reduction in stem elongation was found to be highest in Asra 123 followed by Ronga Lahi. Less reduction in grain yield per hill was recorded in Asra 123 followed by Asra 8 because these genotypes could maintain lower stem elongation with more number of tiller production during submergence. Some genotypes have different degrees of submergence tolerance by maintaining higher CSI, MSI, Photosynthesis, chlorophyll content which may help to maintain growth and development under these conditions. The susceptible genotypes invariably reflected more metabolic de-arrangements in terms of photosynthesis rate, nitrate reductase activity, chlorophyll loss and depression of membrane stability due to higher level of MDA content. In the present investigation Asra 123, Asra 8, Ronga Lahi, Ronga Bao, Bangali Lahi and Suwag Moni Horu could grow successfully under anoxic and showed better performance under submergence.
Open Access
VASE LIFE AND QUALITY OF GLADIOLUS (Gladiolus grandiflora) AS INFLUENCED BY POSTHARVEST CHEMICAL APPLICATIONS
(AAU, Jorhat, 2018-07) NATH, DEB JYOTI; Das, Kaushik
An investigation was carried out during October, 2016 to March, 2017 in the Department of Crop Physiology, Assam Agricultural University, Jorhat-13, to evaluate the effects of different pulsing treatments and holding solutions on vase life and quality of cut gladiolus spikes. In one experiment the cut gladiolus spikes were pulsed with different concentrations of salicylic acid (50ppm, 100ppm and 150ppm), benzyl adenine (50ppm, 100ppm and 150ppm) and nano silver (5ppm, 10ppm and 15ppm) under laboratory condition. Recorded data revealed that moisture content, fresh and dry weights of cut gladiolus spikes were positively influenced by the pulsing treatments. Amount of solution uptake, transpirational water loss and relative leaf water content recorded in cut gladiolus spikes were also altered significantly by the applied pulsing agents. Total carbohydrate content of petals, chlorophyll content of sepals, anthocyanin content of petals and vase life of cut gladiolus spikes were affected appreciably by pulsing treatments in a concentration dependent manner. Among the applied treatments, salicylic acid 150ppm was found to be the best in increasing the vase life of cut gladiolus spikes. In another experiment cut gladiolus spikes were treated with different concentrations of salicylic acid (50ppm, 100ppm and 150ppm), benzyl adenine (50ppm, 100ppm and 150ppm) and nano silver 10ppm as holding treatments under laboratory condition. Combined effects of nano silver (10ppm) with salicylic acid (50ppm, 100ppm and 150ppm) and benzyl adenine (50ppm, 100ppm and 150ppm) were also evaluated. Recorded data revealed that physiological and biochemical parameters in terms of moisture content, fresh and dry weights, amount of solution uptake, transpirational water loss, relative leaf water content, total carbohydrate content of petals, chlorophyll content of sepals, anthocyanin content of petals and vase life of cut gladiolus spikes were increased by different holding treatments. It was further observed that nano silver application significantly enhanced the efficacy of salicylic acid and benzyl adenine in increasing the vase life of cut gladiolus spikes. Among the different holding solutions, salicylic acid 150ppm + 10ppm nano silver + 4% sucrose exhibited the longest vase life (13.65 days). Results of this experiment confirmed that holding treatments exhibited better results compared to pulsing treatments in increasing the vase life of cut gladiolus spikes.
Open Access
Characterization of some upland rice (Oryza sativa L.) genotypes under low phosphorus condition
(AAU, Jorhat, 2018-07) Shyam, Akash; Das, Ranjan
The investigation was carried out for characterization of some upland rice (Oryza sativa L.) genotypes under low phosphorus condition during Jan 2017 to May 2018 in the Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University, Jorhat-13. The main objective of the investigation was to evaluate upland rice cultivars adapted under to low phosphorus condition and to identify the physiological traits contributing to rice growth and development under low phosphorus condition. The study was done to understand the mechanism of phosphorus altering the physiology of rice crop, and its relationship between yield, physiological attributes and nutrient status of rice as influenced by Phosphorus. In first experiment, fifty rice accessions of different genetic backgrounds were used for the evaluation of low-P tolerance. The accessions were grown in two sets of plastic pots; oneset was treated with – P and another with +P using Hoagland solution. Treatment was imposed at 5 days interval. The potential accessions were screened out under the above simulated level of P for studying tolerant ability of the lines using SES scoring. On the basis of SES scoring eight line viz. Kasalth, Ronga Ahu, Amo Amkel, Maipholong, Sesapal, Bizary, Bijor and Haringajali were identified as tolerant to low P.We made an attempt to study, the mechanism of tolerance to low P which was elucidated in second experiment. In the second experiment, the seed of screened lines were grown in the three sets of plastic pot, maintaining the soil with zero “0” level of P (normal soil), second at 10kg/ha of P (moderate dose) and third was maintained at 20kg ha-1 (recommended doses of P). Results obtained during the investigation revealed that P significantly influenced various morpho-physiological, biochemical and yield parameters.A significantly variable response was observed in genotypes due to different levels of P. Due to low P, stress induced reductionin terms of root length, root biomass, shoot dry weight, plant height, specific leaf weight, number of tillers per hill, no. of leaves per hill, and photosynthetic parameters were lower in Maipholong and at par with Kasalath (check line). However, Ronga Ahu and Amo Amkel also showed the similar trend compared to check line under low level of P. A reduction in values of relative membrane stability index and Chlorophyll Stability Index, proline content were recorded under „0‟ dose of P. Under low and moderate P level, a comparatively better performance was recorded in Maipholong and Kasalath in terms of yield and yield related parameter viz. panicle length, number of filled grain and grain yield. The tolerance indices parameter viz. P use efficiency and P uptake revealed that cultivar Maipholong and Kasalath showed maximum in all doses of P followed by Ronga Ahu and Amo Amkel. The susceptible lines invariably reflected less favourable plant P utilization, more metabolic de-arrangements in terms of photosynthesis rate, nitrate reductase activity and depression level of membrane stability. From the results of the experiment it might be concluded that Maipholong and Kasalath was more suitable under low P condition indicating that lines are adaptable to low phosphorus by maintaining better root growth, photosynthesis, chlorophyll stability index, NR activity and NPK level within the plant.
Open Access
PHYSIOLOGICAL BASIS OF ALUMINIUM TOLERANCE IN RICE (ORYZA SATIVA L.)
(AAU, Jorhat, 2019-07) Faqiha, Ph.; Das, Ranjan
The investigation was carried out to evaluate the performance of some rice (Oryza sativa L.) genotypes under different levels ofaluminium during November 2017 to December 2018 in the Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University, Jorhat-13. In first experiment, 149 rice genotypes collected from different North-Eastern States were screened for aluminium tolerancewith two different aluminium levels of 60 μM Al and 100 μM Al using Yoshida solution along with a control. Out of 149 genotypes, seven genotypes viz., Alubari Dhan, Dewri, Ayangleima, Marin Chatpi, Rene Nepung Aam, Rongabetguti and Rajamani were found to be promising in terms of Al tolerance and these were further evaluated in second experiment for mechanism of responses of Al. In the second experiment the screened rice genotypes were grown in potsin three different levels of Alviz.,100 μM Al (T1), 200 μM Al (T2), and 300 μM Al (T3) along with a control (T0) to study the mechanism of the morpho-physiological and biochemical traits contributing to rice growth and development under higher levels of aluminium. Results obtained during the investigation revealed that higher levels of Al significantly influenced on number of leaves, specific leaf weight, leaf area index, membrane stability index, total leaf chlorophyll content, in-vivo leaf nitrate reductase activity, SOD, root volume, root length, root dry weight, plant height and yield attributes in all the genotypes. However, among the seven genotypes Rajamani and Rene Nepung Aam showed less reduction in root length, photosynthetis rate and total chlorophyll. These two genotypes also showed the lowest per cent reduction in grain yield and yield attributesover control. This could be correlated with the increase in superoxide dismutase and proline content in the leaf with proportional decrement of MDA. The genotype Rajamani and Rene Nepung Aam accumulated less amount of aluminium in its root biomass as compared to other genotypes which indicates that this genotype has a better tolerance mechanism by excluding aluminium from the root system thereby contributing better growth and development. Considering the studied morpho-physiological, biochemical and yield related attributes, Rajamani and Rene Nepung Aam genotypes may be considered as the most promising genotypes among all seven genotypes under higher levels of Al in the present investigation.
Open Access
TOLERANCE OF SUMMER GREENGRAM GENOTYPES AGAINST WATER-LOGGING CONDITION
(AAU, Jorhat, 2019-07) Saikia, Bhaskar; Kalita, Prakash
A study was carried out in the Department of Crop Physiology and Stress Physiology premises, F.A., Assam Agricultural University to evaluate the physiological performance of some greengram genotypes as influenced by waterlogging condition of varying duration imposed at different stages of growth. Initially, a total of forty genotypes of greengram were evaluated for their ability to germinate and seedling growth under simulated waterlogged situation in petri-plates. Out of these genotypes, five were selected for further evaluation; they are NVL-855, KM 2355, AKM 12-28, Pratap and Sadiya Local. These five genotypes were further evaluated for their germination, seedling growth and final yield by growing them in pots filled with soil and FYM where inorganic nutrients were also supplied as per recommendation for greengram. The pots were kept under natural condition. Waterlogging conditions were created in the pots for specified length of time at vegetative and reproductive stages of the crop. When the waterlogging condition was imposed during vegetative and reproductive stage, the growth and development of the genotypes were found to be affected adversely. Longer the period of waterlogging, more severe was the affect on growth and development of the plant. Genotypes were found to show similar response to the waterlogging when plants were exposed to waterlogging at vegetative as well as reproductive stage. However, the impact of waterlogging introduced at reproductive stage was found to be more severe on the yield. The values for the traits namely leaf chlorophyll, leaf area, plant height, nitrate reductase activity, seeds/pod, pods/plant, root length, number of root nodules/plant, test weight, total biomass of the plant and harvest index were found to decline under waterlogged condition. Whereas, lipid peroxidase and superoxide dismutase activity showed higher values under waterlogged condition. The performance of the genotype namely Sadiya Local was found to be the best from the point of view of seed yield as influenced by waterlogging. The better performance of this genotype appeared to be related to higher values for the traits namely germination percentage, leaf chlorophyll, nitrate reductase activity, superoxide dismutase activity, number of pods/plant and harvest index. The genotype Sadiya Local showed a decline of 29.82% only in terms of seed yield/plant when the plants were exposed to 12 days of waterlogging at vegetative stage and 38.59% when exposed to 12 days of waterlogging at reproductive stage. The harvest index value were lowered by 12.5% and 20.87% under the waterlogging stress introduced at the vegetative and reproductive stages respectively. The results of the present study revealed that waterlogging has detrimental effects on the growth of summer greengram at all stages of crop growth. But the effects of waterlogging was more detrimental when imposed at reproductive stage compared to early seedling stage, since, it was found to result in a reduction of the harvest index by 28-30% in comparison to12-15% that resulted from waterlogging stress imposed at early vegetative stage. Among the five genotypes studied, Sadiya Local and AKM 12-28 can be considered to be tolerant ones to waterlogging followed by Pratap.
Open Access
PHYSIOLOGICAL EFFECT OF HIGH TEMPERATURE STRESS ON SOME SALI RICE GENOTYPES
(AAU, Jorhat, 2019-07) SAIKIA, KABITA; . Dey, P.C
Plants are sensitive to high temperature during critical stages such as flowering and seed development. With the increase in daily maximum temperature averaged over flowering period above about 360C, rice yield generally declined because of spikelet sterility induced by high temperatures. Rice crop exposure to the spells of high temperature results in grain yield diminish due to spikelet sterility, reduction in source and sink activities, assimilate partitioning. Identifying genotypic variation through field screening for high temperature tolerance is required for initiating successful breeding programme to develop rice cultivars capable of higher yields under projected climatic change conditions. In view of the importance of high temperature tolerance in rice, an experiment was carried out to study “Physiological effect of high temperature stress on some sali rice genotypes” during kharif, 2017 at Regional Agricultural Research Station, AAU, Titabar in split-plot design with conditions (control and high temperature) as main-plot treatment and 33 rice genotypes as sub-plot treatment including N22 as heat tolerant check variety. Heat stress was imposed in the field immediately after PI stage by enclosing the field grown crop with a make shift locally fabricated polythene tent (<92% transmittance), duly supported by bomboo sticks. The polythene cover was removed at the time of harvest. Enclosing the field crop during reproductive phase with polythene sheet had resulted in significant increase in maximum temperature. Another set of same varieties was grown in ambient condition. The increase in maximum temperature was 1-3.50C over the ambient temperature and minimum temperature had increased by 0.5-1.50C. Elevated temperature had no significant effect on mean days to flowering and days to maturity for all the genotypes. However, significant differences were observed between varieties. Among the genotypes IET 26774, IET 26776, IET 26778, 175-2K, S-458, N22 were less affected in morphological traits under high temperature stress. The number of filled grains per panicle is an important yield determining character which was significantly affected by high temperature stress. The sterility percentage were minimum (2-7%) for 175-2K, S-458, IET 26778 due to heat stress. Yield attributes such as panicle weight, harvest index, test weight, panicle number m-2, grain number panicle-1, spikelet number panicle-1 and grain yield were significantly reduced under high temperature stress. Dry matter heat susceptibility index (DMHSI) varied between a minimum of 6.76 (N22) to a maximum of 41.52 (IET 26777). IET 26757, IET 26759, IET 26760, IET 26778, IET 26776, 175-2K, S-458 and N22 are the entries with DMHSI value <15 indicating relative tolerance to heat stress. The grain yield heat susceptibility index (GYHSI) was lowest 11.24 in 175-2K. Amongst the remaining varieties IET 26757, IET 26778, S-458 and N22 performed relatively better with < 15 GYHSI. Exposure to high temperature caused marked reduction in 1000 grain weight. The interaction between genotypes and treatment was found to be highly significant. Minimum reduction in test wt. were observed in IET 26776, 175-2K and S-458 (between 7-9% ) which were less than the check var. N22 (11%). The values for the traits namely leaf chlorophyll, starch content, nitrate reductase activity were found to decline under high temperature stress condition. Whereas, nitrogen content in leaf showed higher values under high temperature stress condition.The desirable traits of maintenance of low profile of the pace of reduction of chlorophyll content, starch content, NR acivity, leaf N content of the varieties viz. IET 26766, IET 26771, IET 26774, IET 26775, 175-2K, S-458 and N22 during high temperature stress condition. The varieties 175-2K, S-458, IET 26778 reflected the inherent capabilities to tolerate high temperature stress with less reduction in grain yield and yield components, grain sterility percentage and other biochemical parameters, could be used as a donor in various breeding programmes also could be adopted in farmer’s field to increase the economic yield.

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