Showing papers in "Indian journal of plant physiology in 2006"

Brassinosteroids - : new class of plant hormone with potential to improve crop productivity

Abstract: Brassinosteroids are a new group of plant growth substances with significant growth promoting activity. In addition, brassinosteroids also confer resistance to crop plants against environmental stresses. The article reviews the studies employing brassinosteroids on crop plants such as vegetables, fruits, cereals, oil seeds and others. It also highlights the constraints faced earlier in large scale field application of brassinosteroids and also presents the current scenario enlisting the commercially available brassinosteroids. The potentiality of brassinosteroids in enhancing crop productivity is discussed.

Nickel alters antioxidative defense and water status in green gram

Abstract: Green gram [Vigna radiata (L.) wikzek] plants exposed to excess nickel (10, 100 and 200 μM) under glass-house conditions were quantified for selected parameters of oxidative stress and water deficit. Supply of excess nickel for 72 h induced chlorosis of young leaves, the effect being most pronounced at 200 μM Ni supply. Excess supply of nickel showed enhanced accumulation of antioxidants ascorbate and dehydroascorbate and decrease in the activity of catalase in the leaves, leading to accumulation of hydrogen peroxide. The activity of ascorbate peroxidase, peroxidase, glutathione reductase and SOD showed an increase. The effect on the enzyme activities varied with the level and duration of Ni supply. Leaves of plants supplied excess Ni showed decrease in water potential (Ψ L ) and relative water content (RWC) and an increase in proline. Results observed indicate that excess supply of nickel interferes with plant water relations and induces oxidative stress.

Brassinolide ameliorates adverse effects of salt stress on germination and seedling growth of rice

Abstract: Rice in general is a salt sensitive crop. Seeds of two cultivars, viz. Kamini (salt susceptible) and Pusa 2-21 (salt tolerant) were allowed to germinate and grow in glass distilled water (control), 150 mM and 300 mM NaCl solutions, 4 μM brassinolide solution, 150 mM and 300 mM NaCI solutions supplemented with 4 pM brassinolide. Seed germination, seedling growth and hydrolytic enzymes (amylase and protease) associated with seedling development were adversely affected by NaCl salt stress. Reduction in DNA, RNA and soluble proteins and increase in peroxidase and free proline in rice seedlings were observed with increasing levels of salt stress. The effect was more conspicuous in Kamini than Pusa 2-21. Brassinolide, a steroidal component of plant origin was found to counter the adverse effect of salt stress irrespective of tolerant (kamini) and susceptible (Pusa 2-21) cultivars. Ameliorative effects of brassinolide were associated with increase in the levels of nucleic acids, soluble proteins, peroxidase and free proline content under salt stress.

High temperature effect on grain growth in wheat cultivars : An evaluation of responses

Abstract: Wheat (Triticum aestivum L) cvs. DL 153-2, C306, HD 2329 and WH 542 were grown under normal (27 November) and late (28 December) sown conditions. In an another experiment these wheat cultivars, except that HD 2285 replaced C306, were grown under normal sowing and at anthesis stage were transferred to control and heated open top chambers (OTCs). Under late sowing, wheat cultivars were exposed to mean maximum temperature upto 3.6°C higher than normal sowing, whereas, under heated OTCs, mean maximum temperature was 3.2°C higher than control OTCs, during grain growth period. In spite of more or less similar increase in temperature during grain growth period by late sowing and in OTCs experiment, the magnitude of responses were different. All the cultivars showed a decrease in yield by late sowing and decrease was greater than OTCs experiment wherein the significant decrease in yield under elevated temperature (ET) was observed only in two cultivars. The main effect of high temperature in OTCs appeared to be on grain size, whereas, in late sowing experiment, different yield components including grain growth rate were differentially affected in different cultivars. Nonetheless, the varietal pattern of susceptibility remained more or less same in late sowing and OTCs experiments. DL 153-2, C306 and HD2285 were relatively heat stress tolerant for grain growth and yield compared to HD 2329 and WH542. The present study further emphasized that late sowing of wheat by end of December can bring down the grain yield by 30-40% compared to November sowing. The late sowing of wheat being generally practiced because of prevalence of rice-wheat cropping system could, therefore, be one of the reasons for overall decline in wheat productivity. It appears that from late sowing experiment, one may not be able to analyse precisely the effect of high temperature experienced exclusively during post anthesis period. By late sowing, pre-anthesis phenological events determining potential yield components would also be affected which were then carried over to grain growth phase and influenced the grain growth and yield.

Screening of landraces of rice under cultivation in Kumaun himalaya for salinity stress during germination and early seedling growth

Abstract: Thirty landraces of rice (Oryza sativa L.) along with an introduced variety VL-206 were screened for seed germination and seedling growth under salinity stress (0.10, 0.15 and 0.20 M NaCl). Among the landraces, Saunji showed maximum germination (90%) even at the highest salinity level (0.20 M NaCl) and was considered most tolerant to salinity stress. The maximum reduction in seed germination was found in Syaudhan (36%) when exposed to 0.20 M NaCl. Early seedling growth in different landraces varied with the salinity level. Increasing the NaCl concentration from 0.10 M to 0.20 M led to a significant reduction in root and seedling (shoot) growth, irrespective of the landrace in comparison to control. The results revealed that a valuable source of rice germplasm, in the form of landraces, is still being maintained through cultivation in remotely located villages in Kumaun region of Indian Central Himalaya, which may be useful for introgression of salinity resistant genes for the development of stress tolerant varieties.

Toxic heavy metal stress in paddy : Metal accumulation profile and development of a novel stress protein in seed

Abstract: Impact of toxic heavy metals lead, mercury and cadmium have been studied in paddy with respect to their impact on harvest index, metal accumulation in grain and plant body and seed protein profile. All the three metals brought about significant decline in harvest index. Lead treatment resulted in 8.85 to 14.06% decline in harvest index compared to control. Mercury also showed similar effect, but cadmium treatment caused 14.29 to 25.0% decline in harvest index. For all the three metals accumulation was highest in roots, ranging from 53.0 to 56.0% for lead, 47.0 to 54.0% for mercury and 66.0 to 69.0% for cadmium. Following roots, accumulation was in descending order in stem, leaf sheath, grain and leaf. In grains, accumulation was 7.0 to 8.0% for lead, 10.0 to 11.0% for mercury and 6.0 to 8.0% for cadmium, clearly indicating the possible health hazard. Seed protein profile analysed through SDS-PAGE revealed elimination of a high molecular weight protein (≥ 120) for mercury and cadmium treatment generated a novel 66.5 kDa stress protein.

Heat and salinity induced oxidative stress and changes in protein profile in Amaranthus lividus L

Abstract: Treatment of Amaranthus lividus L. (a tropical leaf crop) seedlings separately with NaCl (50, 100 & 150 mM) and heat shock for different durations (45°C for 4, 8 & 12 hours) during early germination induced oxidative stress and exhibited coinducibility of some stress proteins. Exposure of Amaranthus seeds to elevated temperature and NaCl salinity caused significant accumulation of reactive oxygen species such as superoxide radicals, hydrogen peroxide and TBARS contents with a reduction of membrane protein thiol level. Both forms of abiotic stress were related to significant reduction of antioxidative efficiency (viz. catalase, peroxidase, superoxide dismutase) and total thiol content. A comparative study of qualitative protein profiles of salinity stressed and heat shock raised seedlings by 8 to 15% gradient SDS-PAGE exhibited, expression of some similar polypeptides having molecular masses 90 and 110 kDa. Both forms of abiotic stress also showed coinducibility of some over expressed proteins. The results clearly suggest that heat and salinity imposed a similar kind of oxidative stress, which might induce the expression of common set of stress proteins.

Physiological analysis of growth and yield of indian mustard as affected by irrigation and sulphur

Abstract: The present study was carried out during rabi seasons of 2003-04 and 2004-05 to find out the effect of irrigation and sulphur on growth and yield characters of Indian mustard. The results revealed that application of two irrigations at 45 DAS and 90 DAS significantly increased plant height, dry matter accumulation, relative growth rate and secondary branches/plant over one irrigation. However, effects of one irrigation and two irrigations were at par on leaf area index, net assimilation rate and primary branches/plant but recorded significantly higher values of above physiological parameters over no irrigation in both the years. Seed yield of mustard increased significantly with increasing levels of irrigation. Application of sulphur also significantly increased the plant height, dry matter accumulation, LAI, RGR, NAR, primary and secondary branches per plant and seed yield of Indian mustard. The significant response was observed up to 45 kg S/ha.

Influence of pre-sowing seed treatment with nitrate salts and different sowing dates on performance of mustard

Abstract: Mustard (Brassica juncea L. Czern and Coss) seeds were soaked for 24 h either in solution of nitrate salts [(Mg(NO 3 ) 2 , Ca(NO 3 ) 2 and KNO 3 )] or in distilled water and sown in field at three different dates of its cropping season. The parameters like plant height, number of leaves per plant, leaf area, leaf area index and net assimilation rate were found to increase with nitrate treatments in comparison to distilled water soaked and control (seeds directly sown in field without any prior treatment) sets. Among nitrates, Mg(NO 3 ) 2 showed better results followed by KNO 3 and Ca(NO 3 ) 2 treatments. The plants raised from first date of sowing showed maximum plant height and leaf area but the mean number of leaves per plant and leaf area index were highest in plants with second date of sowing. Net assimilation rate was found best in the plants of third date of sowing. However the plants raised from second date of sowing showed higher values for most of the parameters in comparison with others. Data regarding yield and yield attributes like pods plant -1 , pod weight plant -1 , pod length, seed pod -1 , seed plant -1 and test weight were increased in nitrate treated sets and in timely sown crops. However nitrate treatment to seeds showed an improvement in overcoming the late sown stress in mustard.

Effect of nitrogen and phosphorus on growth, nutrient content, seed yield and quality of mustard

Abstract: A pot experiment was conducted to study the effect of three levels of nitrogen and phosphorus combinations, i.e. N 60 P 30 kg ha -1 , N 80 P 40 kg ha -1 and N 100 P 50 kg ha -1 on growth, yield and quality of two cultivars of mustard (Brassica juncea). The data revealed that cultivar Pusa Bold gave higher plant height, leaf number, leaf area, number primary branches and plant dry weight than Kranti. Application of higher dose of NP fertilizers, i.e. N 100 P 50 kg ha -1 proved significantly better in improving all these parameters. Higher fertilizer dose also resulted in a significant increase in number of siliqua plant -1 , length of siliqua and number of seeds siliqua -1 , which consequently resulted in a marked increase in harvest index and seed yield of both the cultivars. N 100 P 50 kg ha -1 also resulted in an over all increase in leaf N, P and K contents and seed protein content. Oil content was found to be decreased with increased dose of NP fertilizers, however, extent of decrease in seed oil content was lower than increase in seed yield and thus total edible oil production was still higher with higher fertilizer dose as compared to the normal recommended dose.

Effect of phytohormones on growth, and yield of black cumin (Nigella sativa L.)

Abstract: A pot trial was carried out to study the effect of foliar spray of 0 (de-ionized water), 10 -6 , 10 -5 and 10 -4 M each of gibberellic acid (GA 3 ) or Kinetin (KIN) at 40 days after sowing (vegetative stage) on growth and yield of black cumin (Nigella sativa L.). GA 3 application at 10 -5 M concentration was found to be more effective than KIN in promoting shoot length, plant dry weight, leaf number, leaf area and branch number observed 70 days after sowing (DAS). Application of 10 -5 M GA 3 resulted in more capsule number, seed yield and seed yield merit, which was found increased by 43.33, 43.85 and 53.62% respectively.

Physiological traits contributing to grain yields under drought in black gram and green gram

Abstract: Ten genotypes each of black gram and green gram were evaluated for traits contributing to water use efficiency in a field experiment conduced during Rabi, 2004-05. Under terminal moisture stress conditions there was a significant reduction of SCMR (SPAD chlorophyll meter reading) and SLA (specific leaf area) both in black gram and green gram genotypes. Black gram genotypes PBG 107, LBG 20 and MBG 207, and green gram genotypes MGG 336 and MGG 351 showed higher SCMR and lower SLA under stress. Significant inverse relationship (r=0.73, P<0.05) was observed between SLA and SCMR in black gram genotypes while no correlation was observed in green gram genotypes. Significant positive relationships were observed between seed yield and SCMR both in black gram and green gram under moisture stress, indicating that SCMR could be used as a screening tool for grain yield under drought conditions.

Macronutrient requirement of groundnut : Effects on growth and yield components

Abstract: A series of sand culture pot experiments were conducted to find out the optimum concentration of N, P, K, Ca, and S, in the nutrient solution, for growing groundnut with maximum growth and yield by taking each macronutrient in the range of 2-200 ppm. The observations on plant height, dry matter production, and podding at 20, 40, 60 days after emergence (DAE) and at harvest, chlorophyll content and transpiration at 40 and 70 DAE, flowering from 25-70 DAE and finally pod and haulm yields, at harvest showed that increasing the macronutrients levels, in the nutrients solution, increased these parameters significantly up to a certain level only which was optimum dose for that parameter. The number of flowers produced during the first two weeks (25-40 DAE) of its flowering increased significantly up to 10 ppm of N, P, K, and S and 20 ppm of Ca, but the number of pods at harvest increased up to 50 ppm of N and 20 ppm of P, K, Ca and S. The pod yield and dry matter, chlorophyll, flowering, podding and transpiration at either of the stages, however, increased up to 20 ppm of P and S and 50 ppm of N, K, and Ca and further increase in the levels of these macro-nutrients did not increase these parameters any more significantly. The macronutrient levels of 50 ppm of N, K, and Ca, and 20 ppm of P and S, in nutrient solution, are being recommended for growing groundnut in nutrient culture.

Investigations on the control of fruit drop in alphonso mango

Abstract: Field experiments were conducted during 1998-2002 for identification of pollinizer varieties, control of recurring flowering and control of fruit drop by use of mineral nutrients and growth regulators in Alphonso mango at the Regional Fruit Research Station, Vengurle, Sindhudurg. The investigations revealed that variety Kesar, Ratna and Goamankur were the best pollinizer varieties for Alphonso mango as substantiated by synchrony in flowering with Alphonso, better fruit set and acceptable fruit quality of pollinizer. Alphonso x Alphonso cross combination showed only 4% fruit retention whereas, Alphonso x Kesar, Alphonso x Ratna and Alphonso x Goamankur revealed 10-12% fruit retention. Therefore, plantation of 10 to 15% trees of Kesar, Ratna or Goamankur in Alphonso orchards as pollinizers was recommended. The recurring flowering emerging at the base of old flowering panicle causes heavy fruit drop from adjacent old ones. The foliar spray of GA 3 (50 ppm) at full bloom stage significantly reduced the recurring flowering in Alphonso mango. For control of flower/fruit drop in Alphonso mango, foliar spray of nutrients (urea, KNO 3 , micronutrient complex) and growth regulators (NAA, triacontanol) at different concentrations were tested separately and in combination. The three years data revealed that urea 2%, NAA 20 ppm and micronutrient mixture 50 ppm in combination produced significantly higher fruit yield followed by combined application of urea + triacontanol + micronutrient.

Effect of bioregulators and moisture stress on dry matter accumulation and its partitioning in mustard

Abstract: A field study was conducted during the two consecutive Rabi seasons 2001-02 & 2002-03 to study the role of bioregulators and moisture stress on partitioning of biomass in Brassica juncea. Results revealed that three irrigations (no stress) at BI + 50% flowering + 50% pod development accumulated significantly higher total dry matter per plant over no irrigation (crop under stressed) at physiological maturity. In terms of dry matter partitioning, significantly higher dry matter was allocated to pods under three irrigations. Brassinosteroid (foliar) caused accumulation of maximum total dry matter as compared to rest of the treatments at physiological maturity. Thiourea application (S+F) affected the allocation of dry matter to various organs by translocating of biomass from stem to pods significantly as the pod weight was highest and 62.5 % more compared to control at physiological maturity.

Establishment and influence of phosphate solubilizing bacteria on pearl millet

Abstract: Two Phosphate solubilizing bacterial isolates and their lacZ marked transconjugants were checked for their establishment in the rhizosphere and response on pearlmillet under pot house condition. Seed bacterization showed establishment of PSB in the rhizosphere upto 60 days after sowing. The counts were slightly higher in inoculated treatments compared to uninoculated control. Application of rock phosphate and phosphatic fertilizers increased the biomass by 35-50 per cent over control. The P-uptake also improved with soil amendments and seed inoculation at both stages of sampling.

Sprout suppression of potato tubers stored at 18 °C by pre-and post-harvest application of sub-lethal doses of glyphosate

Abstract: Glyphosate was tried at three concentrations for suppressing the sprout growth of potato (Solanum tuberosum L.) tubers in two cultivars differing in dormancy duration. Single pre-harvest foliar spray of glyphosate [0.833 kg (a.i.) ha -1 ] at 70 days after planting was effective in suppressing the sprout growth with no adverse effect on tuber number and yield. The reduction in sprout growth was 74 % in Kufri Jyoti and 85 % in Kufri Bahar. Higher concentrations of glyphosate resulted in abnormal sprouts with cauliflower like appearance and increased incidence of cracking in larger tubers (>75 g), especially in variety Kufri Jyoti that showed 30 % of this incidence. Post-harvest application of glyphosate reduced sprout growth by 81 % and 78 % in Kufri Jyoti and Kufri Bahar respectively.

Amino acids and soluble protein profile of radish seedlings under salt stress as affected by GA3priming

Abstract: Radish (Raphanus sativus L.) seeds soaked for 24 h in 10 -5 M of GA 3 were germinated under 3 concentrations of NaCl (50, 100 and 200mM) and seedlings use harvested after 4, 7 and 9 d. Total soluble proteins decreased significantly with the increase of NaCl during germination except at 50mM, and the values were always higher with GA 3 priming. Proline decreased with NaCl with and without GA 3 priming. Arginine decreased with 50mM NaCl in the unprimed seedlings and increased in 50 and 200mM NaCl in the primed ones. Glutamic acid and histidine increased in 200mM salt stressed seedlings and histidine in 50 and 200mM in the primed ones. Glycine was absent in both controls and began to appear with 50 and 200mM in the primed and only in 200mM NaCl in the unprimed seedlings. Salinity increased the total essential amino acids and the increase was higher with GA 3 while the non-essential amino acids decreased slightly with 50mM NaCl and the decrease was greater with GA 3 . The total amino acids accumulated with 200mM NaCl in the unprimed seedlings and the opposite was the case with the primed ones due to the sharp decrease in the non-essential amino acids. GOT activity decreased with the increase of NaCl concentration but began to increase again at 200mM NaCl in the primed and unprimed seedlings; its values were however, always, lower in the primed seedlings than in their unprimed counterparts. GPT activity decreased consistently with salinity and its values were lower on priming with GA 3 . The activity of both enzymes increased with germination age. A new protein with MW of >97kD was detected in the primed seedlings treated with 200mM NaCl. A protein with MW of about 21.5 kD existed at all NaCl concentrations, increased with salinity, and its accumulation was greater with GA 3 priming.

Photosynthesis and shade tolerance in tropical range grasses and legumes

Abstract: Seventeen tropical grasses (Bothriochloa bladhii, Brachiaria mutica, Brachiaria decumbens, Brachiaria brizantha, Cenchrus ciliaris, Cenchrus setiger, Chloris gayana, Chrysopogon fulvus, Dichanthium annulatum, Heteropogon contortus, Panicum maximum cv. IGFRI, Panicum maximum cv. PGG 289, Paspalum notatum, Panicum antidotale, Pennisetum polystachyon, Setaria sphacelata, Tri - specific Hybrid (TSH) [(Pennisetum americanum x P. purpureeum) x P. squamulatum] and two legumes [Stylosanthes hamata (Caribbean stylo), and Macroptilium atropurpureum] were studied for their physiological attributes under different light intensities in rain-fed semi-arid conditions. Rate of photosynthesis (P N ) and stomatal conductance (C S ) decreased with decreasing light intensity and reached the minimum level under high shading (25% light intensity). TSH, P. antidotale, P. maximum and S. sphacelata maintained the highest P N and C S under shade followed by B. mutica, P. polystachyon and C. ciliaris indicating their adaptation to shade. In legumes, S. hamata maintained higher P N than M. atropurpureum under moderate shading (50%) and can be grown with trees having sparse canopies in tree-crop inter-cropping systems. Transpiration rate (T R ) at 25% light intensity was half that in full sunlight. TSH, B. mutica, P. maximum, P. antidotale, S. sphacelata, P. polystachyon and S. hamata relatively maintained higher carboxylation efficiency and water-use efficiency (WUE) under shade followed by C. ciliaris, C. setiger, C. fulvus and B. bladhii. Chlorophyll content (a + b) was maximum under 50-75% shading in most of the species.

Crop growth and fruiting characteristics of brinjal as influenced by gravity drip irrigation

Abstract: The results of experiment on low cost gravity drip irrigation in winter brinjal crop (cv. Muktakeshi) revealed that maximum plant height, leaves and flowers were recorded with surface irrigation and 100% ET o / ET c treatments. Drip irrigated plant became stunted and leaf numbers and flowers per plant decreased with water supply at lower replenishment of ET c . Branching of plant was more under drip-irrigated crop. Higher moisture supply widened flower to fruit ratio (1: 5.4 - 5.6). Reduced water supply by 80 and 60% ET c caused early flowering and improved flower to fruiting ratio, but reduced the flower number and fruit size. The maximum fruit yield (162.8 - 176.8 q ha -1 ) was obtained with increased water supply but reduced water supply did not hamper yield significantly. Drip irrigation with fertigation was noticed superior in fruit yield over surface method of water supply. Drip irrigation saved 37 - 49% water over surface irrigation.

Kinetics of nitrate uptake system in wheat genotypes

Abstract: The nitrate uptake kinetics (C min , K m , and V max ) were studied in two cultivars of wheat differing in the level of activity of enzyme nitrate reductase. The uptake kinetics especially K m and V max depend on the concentration of nitrate in rhizosphere. At low range of external nitrate concentration uptake system follows Michaelis-Menten saturation kinetics, while at high external nitrate concentration, the nitrate uptake system follows linear kinetics. The uptake system did not show any saturation at least up to 10mM external nitrate. Lineweaver-Burk plot transformation of the uptake data at low nitrate concentration, the K m and V max of HD 2285 (high nitrate reductase activity-HNR) and HD 1981 (low nitrate reductase activity-LNR) were found to be 0.186 and 0.725 mM, and 0.17 and 0.798 mmol g -1 fr. wt. h -1 , respectively. The C min was calculated by estimating the accumulation of tissue nitrate and found to be 0.9 and 1.5 mM. At low range (0.05-0.5), the rate of nitrate uptake was higher in LNR genotype and at high external nitrate concentration, the uptake of nitrate was more in HNR genotype.

Uptake of mercury, cadmium, uranium and zinc by Mimosa pudica

Abstract: Efficiency of uptake of known pollutant heavy metals Hg, Cd, U and Zn by Mimosa pudica, a non-consumable wild plant species, was evaluated. Various concentrations of heavy metals ranging from 1-10, 1-20, 5-20 and 50-200 mM were used and maximum uptake by the roots at 10, 20, 10 and 100 μM recorded for Hg, Cd, U, and Zn, respectively. The translocation of metals from root to stem (48%) and leaves (8%) was highest for Zn, as compared to others. U showed only 35% translocation to stem, where as Cd and Hg translocation to both stem and leaves, was negligible. The results indicated differential uptake for different metals by Mimosa pudica. The roots showed maximum uptake capacity for heavy metals, implying the possible utility of Mimosa pudica for rhizofiltration.

Effect of dikegulac on flowering, fruit setting and development of Cucumis sativus L

Abstract: Foliar application of dikegulac sodium (2,3:4-6-di-O-isopropylidene-α-L-xylo-2-hexalofuranosate) had promotive effect on flowering, fruit setting and fruit development of Cucumis sativus. It suppressed male flowering and promoted female flowers. Dikegulac at 50mgl -1 increased the length and girth of the fruits by 46.3% and 81.5% respectively. With the same concentration, the weight of the fruits was increased by 38.8%. Dikegulac (50mg l -1 ) also improved the quality of the developing fruits by increasing the contents of insoluble carbohydrate and ascorbic acid in the fruits at 15 days of age.

Physio-biochemical evaluation of some improved mulberry varieties in the gangetic alluvial soils under irrigated conditions

Abstract: Ten improved mulberry varieties, viz. V1, C1730, C2016, C2017, Anantha, RFS-175, Thallaghatapura, Vishala, S1 and S1635 were evaluated for physiological and biochemical parameters under irrigated conditions in the alluvial soils of Gangetic plains of West Bengal as per zonal schedule. Leaf area, leaf fresh weight, % moisture content and moisture retention capacity were found to vary significantly among the varieties tested. Moreover, net photosynthetic rate, transpiration rate, physiological water use efficiency, stomatal conductance and biochemical parameters, viz. total chlorophyll, total soluble sugar, nitrate reductase activity, total soluble protein and phenol content also showed significant variation among the tested varieties. Among the varieties S1635 was recorded to have higher leaf area (305.70 cm 2 ), leaf yield (0.520 kg/plant/crop), fresh leaf weight (4.92 g), net photosynthetic rate (14.66 pmol CO 2 m- 2 s -1 ), nitrate reductase activity (13.25 μmol NO 2 - h -1 g -1 fw.), chlorophyll content (2.13 mg g -1 fw.), total soluble sugar (48.44 mg g -1 fw.) and total soluble protein (39.63 mg g -1 fw.) were also higher in S1635 showing its superiority over other tested varieties. The studies suggested that S1635 can be commercially exploited for cultivation under irrigated conditions in the Gangetic alluvial soils of West Bengal.

Effect of cadmium on growth, mineral composition and enzyme activity of sugarcane

Abstract: An attempt has been made to study the effect of differential levels of Cd (0, 5, 10, 100, 200 ppm Cd as cadmium chloride) on growth, cell division, chlorophyll content, and activity of catalase and peroxidase enzymes, foliar anatomical characters and essential nutrient contents in sugarcane (Sachharum sp. hybrids CoLk 8102 and CoJ 64) planted under soil pot culture conditions. Very low levels of Cd (5 and 10 ppm) decreased most of the growth attributes studied, viz. leaf number, leaf area, plant height, leaf width, fresh and dry weight of different plant parts, reduction being more with an increase in Cd supply. In variety CoLk 8102, the depression was 45, 51 and 71% in leaf number, plant height and leaf area respectively whereas CoJ 64 exhibited 18, 11 and 15% depression at 200 ppm Cd supply. Cytological studies indicated steady decline in mitotic index with increasing Cd dose in both the varieties. Chlorophyll a and b and soluble protein contents decreased with an increase in Cd supply in both the varieties. Peroxidase activity was found high while catalase activity was low in Cd supplied plants. Foliar anatomical studies indicated marked reduction in number of minor veins of LTM leaves but the major veins were not affected due to Cd addition in growth medium. Essential nutrients, viz. P, Fe, Mn, Cu and Zn determined in different plant parts revealed lower content of P, Fe, Mn Cu and Zn in leaves and higher content of Fe and P in root tissue at higher Cd levels (100 and 200 ppm Cd). Results obtained indicated that high dosages of Cd (100 and 200 ppm Cd) exerted significant inhibitory effect on shoot and root growth, cell division coupled with changes in mineral composition, activity of catalase and peroxidase enzymes which in turn resulted in reduction in biomass yield of sugarcane. Both the varieties were affected due to excess Cd, effect being less pronounced in variety CoJ 64 in terms of lower decrease in growth attributes.

Chlorophyll fluorescence transients with response to leaf water status in coconut

Abstract: Leaf water potential ( φ leaf) and chlorophyll fluorescence (Chl. F) transients were determined in coconut seedlings in the field under intermittent irrigated (non-stress) and un-irrigated (stress) conditions. Stress was imposed by withholding irrigation to the seedlings. With reduction in Ψ leaf , associated with the increase in soil water deficit as well as micrometeorological variables, the Chl. F traits showed variation. Re-irrigation of the seedlings, although showed recovery of the leaf water status, did not show recovery to the PS II system as revealed by Chl. F values. The reduction in various fluorescence derived ratios viz, Fv/Fm and Fm/Fo as well as t 1 /2 (the half rise time from Fo to Fm) implied the blockage of electron flow on the waterside of the PS II and damage to the photochemical apparatus with stress. Observations during different treatment periods clearly revealed that in coconut PS II is highly sensitive to agro-meteorological variables and prolonged drought lead to permanent damage to photosynthetic apparatus. Hence, maintenance of water status of both soil and leaf is highly crucial to protect the PS II system in coconut seedlings during summer months.

Endogenous levels of plant growth substances in seeds of five bamboo species in relation to seed viability

Abstract: Endogenous levels of auxins and ABA in seeds is found to be one of the major factors related to the loss in seed viability in stored bamboo seeds. This was examined during storage for one year, under controlled conditions, in 5 bamboo species by means of various viability tests. Endogenous levels of putative free indole acetic acid (IAA) and free and bound abscissic acid (ABA) were measured in freshly harvested seeds and in seeds stored for one year. In freshly harvested seeds, free IAA levels were higher in all species in comparison to one-year-old seeds. Seeds of Thyrsostachys siamensis showed highest viability (G% 76.6) and maximum content of IAA (2.90 μg g -1 fw) while the seeds of Dendrocalamus strictus showed lowest viability (G% 5.53) and lowest content of IAA (2.07 μg g -1 fw). Same pattern of IAA was observed in seeds stored for one year but the IAA levels were found to be reduced and so did the viability across all species. The free and bound ABA levels in freshly harvested seeds were maximum in D. strictus, with lowest viability. After one year, the amount of free ABA increased by about 58% while the bound ABA was found to be reduced by 78% in this species.

Selection of salt tolerant somaclones from indica rice through continuous in vitro and ex vitro sodium chloride stress

Abstract: This study aimed at the selection of salt tolerant somaclones from four Bangladeshi indica rice genotypes through in vitro and ex vitro NaCl stress applied through step wise and non-step wise methods. Callogenesis was initiated under four different levels of non-step wise NaCl stress (50, 100, 150 and 200 mM) and subsequent plant regeneration was observed under same levels of NaCl stress. Among the four genotypes Binnatoa and IR51491-AC5-4 produced fertile somatic embryos with relatively high NaCl (150 mM) stress. BRRI dhan29 and BRRI dhan40 produced fertile somatic embryos only from 50 and 100 mM NaCl stress conditions. Ex vitro (glass house) step-wise NaCl stress was applied to in vitro selected somaclones at the seedling (50, 100, 150 and 200 mM) and following booting stages with simultaneous acclimatization. Satisfactory seedling survival was observed for all genotypes up to 150 mM NaCl stress. Advanced flowering was observed mostly for all the genotypes when stress was applied at the seedling stage compared with combined stress at both seedling and booting stages. Fertile SC1 generations were observed for genotype IR51491-AC5-4 and Binnatoa up to 200 mM NaCl stress applied at the seedling and both seedling and booting stages. Information on transmission of somaclonal variation to sexual progeny is required for further exploitation of potentially useful variants.

Screening of groundnut genotypes for high water use efficiency and temperature tolerance

Abstract: An experiment was conducted during post rainy season of 2001-02 at Regional Agricultural Research Station, Tirupati with 111 spanish and 110 virginia groundnut genotypes. The genotypes were screened for moisture stress and high temperature tolerance and were classified into 3 groups, viz. low, medium and high for SPAD chlorophyll meter reading (SCMR), SLA, chlorophyll fluorescence ratio and membrane injury. Majority of the spanish genotypes had medium SCMR (45-50) and SLA (125-150), while most of the virginias had high SCMR (>50) and medium SLA (125-150). Majority of the spanish and virginia genotypes screened had high membrane injury of >60%. Significant variation was observed between the genotypes for SCMR, SLA, chlorophyll fluorescence ratio and membrane injury. Spanish genotype TIR-21 showed less reduction in F v /F m ratio when exposed to temperatures of 45°C (1.13% reduction) and 55°C (22% reduction), while virginia genotype TIR-34 maintained high F v /F m ratio at temperature > 50°C. Genotypes TIR-20 and JAL-31 showed a higher reduction of 84 and 82% respectively in F v /F m ratio when exposed to 55°C. Spanish genotype JAL-07 had a low membrane injury (37%). Incidentally, it also maintained high SCMR (52) and low SLA (101.6cm 2 g -1 ), indicating that it can tolerate both water deficit and high temperature. However, this genotype showed more reduction (62%) in F v /F m ratio at 55°C. Virginia groundnut CSMG84-1 showed low membrane injury (34%). Thus the genotypes TIR-21, TIR-34, JAL-07 and CSMG 84-1 are better for higher temperatures and hence can be recommended for the specified situation in order to increase the yield potential under high temperature conditions.

Effect of seed inoculation and farmyard manuring on nitrogen balance and yield in rajmash (Phaseolus vulgaris)

Abstract: A field experiment was conducted during 1999 and 2000 at Highland Research and Extension Centre, Kukumseri, Lahaul and Spiti to study the influence of Rhizobium inoculation, incorporation of farmyard manure (FYM) and fertilizer nitrogen (N) on nodule number and weight, nitrogen fixation in rajmash and N balance in the soil. The inoculation of Rhizobium leguminosarum bv.phaseoli to seed and incorporation of FYM one week before sowing of rajmash increased the seed yield. Similarly, inoculation of seed enhanced N fixation and incorporation of FYM left a net positive balance of 42 and 84 kg N, respectively. Though application of excess nitrogen also showed a net positive N balance, it reduced N fixation in rajmash. A higher accumulation rate of available N at the all growth stages of rajmash was observed with incorporation of FYM and inoculation of seed over control.