SPAD Chlorophyll Meter Reading Research Articles

Residual Effect of Nitrogen and Weed Management Practices in Maize on Succeeding Groundnut

Background: Cereal-legume cropping system is considered to be one of the better alternatives for sustaining soil fertility and increasing the yield. At present maize-groundnut cropping system is gaining importance under both rainfed and irrigated situations. Maize, being an exhaustive and weed-sensitive crop, is supplied with large doses of fertilizers and new herbicide molecules.Since maize is exhaustive and weed sensitive crop, there was a usage of excessive fertilizers and new herbicides. There is a need to assess the carry over effect of fertilizers and new generation herbicides in leguminous crops like groundnut. Methods: The experiment was conducted during two consecutive rabi seasons of 2019-20 and 2020-21 on sandy loam soils of S.V. Agricultural College, Tirupati andhra Pradesh. Maize hybrid DHM -117 was sown and maintained with general cultivation practices except for nitrogen and weed management methods was raised after harvest of maize in undisturbed layout to study the residual effect of different nitrogen and weed management practices imposed in maize. Result: Residual effect of nitrogen and weed management practices imposed in preceding maize did not exert any significant influence on germination percentage, phytotoxicity and SPAD chlorophyll meter reading (SCMR) values but efficacy of herbicide residue found to be significant with weed management practices. Growth parameters, yield attributes pod yield, haulm yield and economics were higher in groundnut with brown manuring, which was however, in parity with hand weeding twice at 15 and 30 DAS, pre emergence application of atrazine 1.0 kg ha-1 fb post emergence application of topramezone 30 g ha-1 and pre emergence application of atrazine 1.0 kg ha-1 fb post emergence application of tembotrione 120 g ha-1 and lower with unweeded check and it was remained in parity with application of parthenium water extract15 lha-1 twice at 15 and 30 DAS, application of sunflower water extract 15 lha-1 twice at 15 and 30 DAS, pre emergence application of atrazine 1.0 kg ha-1 fb post emergence application of parthenium water extract 15 lha-1 and pre emergence application of atrazine 1.0 kg ha-1 fb post emergence application of sunflower water extract 15 lha-1 in the order of ascent. None of their interaction effects were found to be significant during both the years of study and in pooled mean.

Evaluation of Advanced F4 Groundnut Breeding Lines for Chlorosis Tolerance, Morphological and Yield Parameters under Lime-induced Iron Chlorosis Condition

Iron deficiency chlorosis, a major physiological disorder affecting the groundnut production worldwide and is prevalent in alkaline and calcareous soils with a pH of 7.5 to 8.5. Identifying and developing a chlorosis tolerant genotype is the best solution to overcome this major abiotic stress in calcareous soils. Therefore, a field experiment was conducted at University of Agricultural Sciences, Dharwad, in June, 2019 under rainfed conditions to evaluate a set of sixteen advanced breeding lines along with three parents of groundnut checks for chlorosis tolerance, morphological and yield parameters. Associated traits like SPAD chlorophyll meter reading (SCMR) and visual chlorotic rating (VCR) were assessed to evaluate the chlorosis tolerance. Among the parents, lime induced iron chlorosis (LIIC) tolerant parent, ICGV 86031 had recorded higher SCMR value and lower VCR (35.62 and 2.40, respectively) at 60 DAS with lower plant height, higher number of branches per plant, total dry matter production and pod yield (19.27cm, 5.20, 9.34g and 9.21g, respectively) at harvest compared to LIIC susceptible parents. However, among the derived breeding lines, TIP 16-5 recorded higher SCMR value and lower VCR (28.82 and 1.72, respectively) at 60 DAS with higher plant height, number of branches and total dry matter (26.29 cm, 5.33 and 12.80g, respectively) at harvest over the respective susceptible parent TMV 2. Further, TIP 16-5 and JIP 29-14 recorded about 50.47 and 31.46 per cent increased pod yield over their susceptible parents. These results indicate introgression of dry matter production, pod yield and chlorosis tolerance from the tolerant parent.

Dissecting the Genetic Relationship between Root Morphological Traits with Grain Yield of Introgression Lines (ILs) Derived from Wild Rice (Oryza rufipogon Griff) under Low Soil Phosphorous Condition

Soil phosphorous (P) deficiency is one of the limiting factors in rice production in both upland and rainfed lowland ecosystems. Since P is diffusion limited in depleted root zones, understanding the link between root morphological traits and yields is crucial for improving rice productivity. To understand this link, phenotypic screening experiment was conducted for the 38 ILs (BC1F6) derived from the wild rice (Oryza rufipogon Griff) along with the six checks in specialized low P plots and normal soil P (RDF) plot at ICAR-IIRR, Hyderabad during rice growing season Kharif-2020 by adapting augmented block design. The genotypes were screened for grain yield along with root traits such as tiller number per plant (TN), shoot length (SL), root length (RL), root volume (RV), shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), root dry weight (RDW), root to shoot ration on wet weight basis (RSRWW), root to shoot on dry weight basis (RSRDW), SPAD chlorophyll meter reading (SCMR). The results from ANOVA revealed that, MSS due to genotypes, (checks + genotypes) were significant ((p<0.01 and p<0.05)) for most of the root architectural traits and for two different regime of P under investigation. Wide range of genetic variation was recorded for the traits such as RL, RV, SFW, SDW, RFW, RDW, RSRWW, RSRDW and GYP with high GCV and PCV and high h2 coupled with high GAM under both P gradient conditions. Strong inter-correlation among the component traits was observed for the root traits such as RV (0.43**: 0.50**), SFW(0.81**:0.60**), SDW (0.65**: 0.81**), RFW (0.87**:0.64**), RDW (0.83**: 0.87**) and RL (0.36**: 0.43**) along with GYP (0.52**) under low soil P and normal soil P. Principal component analysis with first four PCs revealed existence of 69.40 and 70.30% of total variance and clustering analysis identified the promising genotypes as IL-9-10, IL-11-2, IL-21-8, IL-19-3, IL-22-1, IL-23-2, IL-23-7, IL-31-3, IL-42-3, IL-67-2, IL-69-1, IL-75-2, Swarna and Rasi with root traits RV, RDW, RFW, RL, and GYP are effective traits for rice cultivation.

The Roles of Net Photosynthetic Rate and Transpiration Efficiency on Economic Yield of Jerusalem artichoke (Helianthus tuberosus L.) Genotypes under Different Drought Durations during the Terminal Growth Stages

Knowledge of the influence of different drought durations during the terminal growth stages on net photosynthetic rate (Pn), transpiration rate (Tr), transpiration efficiency (TE), and tuber fresh weight (economic yield) is relatively limited in Jerusalem artichoke. Our aim was to examine the effect of different drought durations during the terminal growth stages on Pn, Tr, TE, and economic yield in Jerusalem artichoke genotypes with different ranges of drought tolerance. A two-year field experiment was established in the northeast of Thailand. A split-plot design replicated four times was used. Three water treatments, optimal conditions (SD0), short-drought (SD1), and long-drought (SD2) durations during the terminal growth stages, were arranged as main plots. Six genotypes (HEL256, JA37, HEL253, JA4, JA60, and JA125) are subplots. Different durations of drought in SD1 and SD2 reduced Pn, Tr, and economic yield, while drought stress during the terminal growth stages increased TE in whole genotypes over SD0 treatments. Drought-tolerant genotypes JA125 and JA4 exhibited high Pn, medium TE, and low economic yield reduction under SD2. Utilization of these superior parents in breeding could lead to the generation of new progenies with high economic yield productivity and drought tolerance during the long drought duration during the terminal growth stage. In addition, high SPAD chlorophyll meter readings (SCMR) in SD1 and SD2 and low specific leaf area (SLA) in SD1 could be used as indirect selection traits to survey high Pn genotypes in Jerusalem artichoke. Consequently, these indirect selection traits may allow for speedy breeding programs in Jerusalem artichokes.

Estimation of Genetic Variability Parameters and Parent-offspring Correlation, Regression in Groundnut (Arachis hypogaea L.)

Genetic variability is major component which helps in selecting better genotypes under different environmental conditions, with this aim an experiment was conducted to understand the genetic potential, heritability, genetic advance and traits association of yield contributing characters for F6 and F7 families derived from the cross GKVK-6 × KCG-2 at the University of Agricultural Sciences, Bangalore in an augmented block design along with three checks viz., TMV-2, KCG-6 and KCG-2 during summer and Kharif 2017. Results from analysis of variance (ANOVA) revealed that highly significant differences were observed for all the characters studied. High genetic variability was observed for major yield contributing characters like the number of pods per plant (g), pod yield (g), kernel yield per plant (g), SMK% (sound mature kernel per cent), SCMR (SPAD chlorophyll meter reading) and SLA (specific leaf area) (cm2/g). Narrow difference between GCV (genotypic coefficient of variation) and PCV (phenotypic coefficient of variation) was observed for pods per plant, pod yield, SCMR and SLA and high heritability coupled with moderate genetic advance per cent mean was recorded for pod yield, SCMR and SLA indicating the involvement of additive gene action in controlling these traits. Three superior families were noticed with more pods plant-1, high pod yield plant-1, high kernel yield-1, high shelling (%), high SMK (%), high SCMR value, and low SLA value. Further, these superior families also revealed the presence of high parent offspring regression and intergeneration correlation, implying increased efficiency of selection for most of the traits considered and these were identified to be the important characters that could be used in selection for yield Keywords: GCV, PCV, Heritability, GAM, water use efficiency, Groundnut.

The responses for inulin content and inulin yield of Jerusalem artichoke (Helianthus tuberosus L.) genotypes and the associations of net photosynthetic rate with inulin traits to different terminal drought durations in the late-rainy season

• The Jerusalem artichoke genotypes which are able to maintain a high net photosynthesis rate under long terminal drought conditions led them to high inulin yield. • SPAD chlorophyll meter reading traits mainly contribute to high inulin content under short terminal drought conditions in HEL256, JA37, JA60, and JA125. • Jerusalem artichoke genotypes with performing high inulin content would be positive for sustainable improvement of drought tolerance under different durations of terminal drought.. Different terminal drought durations might impact inulin traits of Jerusalem artichoke (JA) and some physiological traits are expected to be relevant to their genotype response. Therefore, the aims of this study were to investigate the effect of different durations of terminal drought on inulin content and inulin yield as well as the associations among inulin traits, net photosynthesis rate (P n ), and SPAD chlorophyll meter reading (SCMR) in JA genotypes. The field experiment was designed as a split-plot design with four replications during the late-rainy seasons over two years (2017/18 and 2018/19). The main plots were three water levels composed of optimal conditions (SD0), short (SD1), and long (SD2) durations of terminal drought. Six JA genotypes (HEL256, JA37, HEL253, JA4, JA60, and JA125) were arranged in subplots. All genotypes showed that inulin content in tubers was clearly significantly increased, whilst inulin yield drastically decreased under different terminal drought durations in comparison with optimal conditions. Among six genotypes, only HEL256, JA37, JA60, and JA125 had high inulin content coupled with high P n under SD0, and they had high inulin content under SD1, mainly due to high SCMR. JA37, JA4, JA60, and JA125 had a high inulin yield under SD2, might be they had high P n , indicating that these genotypes could be used as potential parental lines through plant breeding programs for the improvement of new varieties suitable for growing in terminal drought prone-areas. Based on data for two years, inulin content had significant positive associations with P n ( p < 0.01) and SCMR ( p < 0.05) under SD0 and SD1, respectively. Inulin yield showed significantly ( p < 0.05 for 2017/18 and p < 0.01 for 2018/19) positive associations with P n under SD2, these results indicated that selection genotypes with high P n and SCMR could be effective as an indirect selection in acquiring high inulin traits simultaneously. Finally, our results suggest that SCMR could be used as a surrogate trait as it is a simple tool for drought-tolerant genotype screening in JA in order to identify high inulin content in tubers under short terminal drought durations.

Potential of sweet sorghum (Sorghum bicolor L.) cultivars under different water regimes for some agronomic performances, juice yield and related traits

Continued evaluation for drought tolerance on crops with high potential is an important factor in mitigating the effects of climate change and in the long run secure enough food and alleviate world hunger. Sweet sorghum is one of the multifunctional crops which has shown potential as food, industrial and bioenergy source, thus it is important to study its potential under various conditions. A pot study was conducted in early rainy season (March-August 2020), the experiment was arranged 3 × 2 factorial in RCBD with four replications. Factor A was 3 water regimes (FC, 2/3AW and 1/3AW), factor B was two sweet sorghum cultivars [cv. Suwan Sweet Extra (Thai sweet sorghum) and SSV74 (imported from India)]. The results revealed that significant differences were not observed among water regimes in most traits i.e. plant height, stalk diameter, relative water content (RWC), stalk fresh weight and juice yield in harvesting day. This could suggest that sweet sorghum will perform well in any moisture condition, most importantly in lesser moisture environments. Significant differences were observed among sweet sorghum cultivars in several traits i.e. spad chlorophyll meter reading (SCMR), chlorophyll content, brix value, root dry weight, juice yield and R/S ration at harvesting day. Relationship among traits were also observed but the most interesting results was where we found juice yield having negative correlation to brix value (r=-0.736***) and another no correlation was observed between stalk weight and juice

Phenotyping RIL Population to Identify Water Deficit Tolerant Lines in Groundnut (Arachis hypogaea L.)

Background: Genotype sensitivity to mid-season drought suggests the possibility of identifying genotypes with high yield potential and low sensitivity to mid-season droughts. The overall objective of the present research was to select genotypes with high tolerance to mid-season moisture stress. This effort includes assessing the variation of physiological and productive traits among RIL population lines, assessing the range of correlation for physiological and productive traits across two seasons and identifying a set of contrasting material under drought stress conditions. Methods: To assess the recombinant inbred lines (RIL) under moisture stress, we screened RIL population of groundnut with 432 lines and parents under mid-season drought stress conditions in rabi for two years. During the drought stress period, soil moisture content (SMC) and temperatures were measured. SPAD chlorophyll meter reading (SCMR), specific leaf area (SLA), relative water content (RWC), visual wilting rate (VWR) and canopy temperature (CT) were recorded at the end of the stress period. Pod yield per plant (PYPP), kernel yield per plant (KYPP) and shelling percent (SP) were recorded at harvest. Result: Physiological traits and yield attributes varied significantly among the RIL population. The Genotype by Trait biplot (GT biplot) revealed that the yield attributes showed a positive association with RWC, SCMR and a negative association with SLA, VWR and CT. The inbred lines were classified as visually healthy with high physiological and high or moderate yield traits; visually wilting with low physiological and low yield traits under a drought environment. The identified superior and inferior lines werefurther utilized to analyze genomic regions and genes for drought tolerance in groundnut.

Response to Drought Stress in a Subset of the U.S. Peanut Mini-core Evaluated in Oklahoma, Texas, and Virginia

In many parts of the world, limited water and climate change are significant challenges to the future of peanut production, and much work remains in developing heat- and drought-tolerant cultivars. To this end, we evaluated 21 accessions of the U.S. peanut mini-core under water-limited conditions in 2018 and 2019 in Oklahoma, Texas, and Virginia. These accessions were identified as potentially exhibiting phenotypic extremes for ten drought stress traits, and therefore may be useful for identifying genetic markers associated with drought tolerance. Results indicated that plant wilting and paraheliotropism (leaf folding) were less affected by genotype by environment interactions than SCMR (SPAD chlorophyll meter readings), flower counts, yield, TSMK (total sound mature kernels), and seed weight. No differences among genotypes were observed with canopy temperature, canopy temperature depression, or NDVI (normalized difference vegetation index). Paraheliotropism was moderately correlated (|r| = 0.40 to 0.52, P &lt; 0.01) with SCMR and flower counts in the Southwest; SCMR was also correlated with yield and TSMK (r = 0.48, P &lt; 0.01). Despite environmental differences between subhumid Virginia and the semiarid Southwest, the locations shared genotypes at the extremes for most traits. This information may be useful for future studies by highlighting traits associated with drought tolerance that may be more stable in different production environments, as well as divergent genotypes for those traits.

Study of gene action for yield and quality traits in rice (Oryza sativa L.)

The present experiment was conducted to study the gene action, heterosis, inbreeding depression and heritability for different yield and quality traits in the cross WGL 48684 x IR 36. Analysis of heterosis revealed that most of the traits show duplicate type of epistasis which is non- fixable and cannot be exploited through the general breeding procedures of self pollinated crops. Additive gene effect and complementary epistasis plays a lead role for plant height, number of ear bearing tillers per plant, kernel breadth and amylase content and they can easily be exploited for developing fixed lines. Significant inbreeding depression was found for ear bearing tillers per plant, SPAD Chlorophyll Meter Reading (SCMR), harvest index, grain yield, head rice recovery and kernel elongation ratio. Therefore, few cycles of recurrent selection followed by pedigree method would be effective and useful to utilize all types of gene effects by maintaining considerable heterozygosity through mating of selected plants in early segregating generations.

Genetic mapping of tolerance to iron deficiency chlorosis in peanut (Arachis hypogaea L.)

Iron deficiency chlorosis (IDC) under calcareous and alkaline soils is a significant abiotic stress affecting the growth and yield of peanut. In this study, the genomic regions governing IDC tolerance were mapped using a recombinant inbred line (RIL) population derived from TMV 2 (susceptible to IDC) and TMV 2-NLM (tolerant to IDC), which was phenotyped during the rainy seasons of 2019 and 2020 in the iron-deficient calcareous plots. The best linear unbiased prediction (BLUP) values for IDC tolerance traits like visual chlorotic rating (VCR), and SPAD chlorophyll meter reading (SCMR) were used for QTL analysis along with a genetic map carrying 700 GBS-derived SNP, AhTE and SSR markers. In total, 11 and 12 main-effect QTLs were identified for VCR and SCMR, respectively. Among them three QTLs were major with the phenotypic variance explained (PVE) of 10.3–34.4% for VCR, and two QTL were major for SCMR with PVE of 11.5–11.7%. A region (159.3–178.3 cM) on chromosome Ah13 carrying two QTLs (one each for VCR and SCMR) was consistent with the previous report. A SNP marker, Ah14_138037990 identified from single marker analysis for VCR was located in the intronic region of the gene Arahy.QA0C1, which is important for protein-binding. Overall, this study identified new QTLs and also validated QTL for IDC tolerance. These genomic resources could be useful for genomics-assisted breeding of peanut for IDC tolerance.

Genetic Variability and G×E Interactions in a Diverse Set of Groundnut Accessions

Background: Knowledge of the genetic diversity for various agronomic traits and their interaction with the environment and subsequent classification of genotypes will be beneficial for identification of divergent and stable sources of agronomic traits. Methods: A set of 96 groundnut germplasm accessions belonging to four botanical groups were evaluated for three years (2017 to 2019) for pod yield and component traits using AMMI analysis and subsequently accessions were classified based Euclidean cluster analysis. Result: Among different botanical groups, Virginia genotypes matured late and possessed high SPAD chlorophyll meter readings (SCMR) and pod yield compared to Spanish types. The component traits of pod maturity like days to flowering (first and 50%) showed low heritability and high genotype × environment interaction (GEI) and significant negatively affected sound mature kernel (SMK) and shelling per centage (SP). The cumulative contribution of environment and GEI component to the total variance was the highest in the expression of SP (67%) followed by days to maturity (54%) and days to 50% flowering (52%). Euclidean distance-based cluster analysis grouped the 96 accessions into five major clusters. Cluster I had accessions with higher pod yield, whereas cluster V contained accessions with low SLA, high SCMR and moderate pod yield. High yielding as well as stable accessions identified based on AMMI stability value (ASV) are NRCG 17332, 10076, 17268, 17197, 17108, 10106, 10089 and 17165. Trait specific as well as stable accessions identified in the present study can be useful donors for groundnut breeding programme.

Genotype by Trait Biplot Studies on Yield, Physiological and Nutritional Traits in Pearl Millet [Pennisetum glaucum (L.) R. Br.

A field experiment was conducted at Dry land farm, S.V. Agricultural College, Tirupati in Kharif 2018 to study the effect of Plant Growth Regulators and micronutrients on growth, yield and quality of sorghum. The objective of the study was to assess the visual comparison among genotypes on the basis of multiple traits and also to graphically describe the interrelationships among all measured traits on the basis of overall pattern of the data for the 42 genotypes of pearl millet that were evaluated for 22 physiological, nutritional, and yield related traits in a randomized complete block design, using GT biplot analysis through which, the principal components PC1 and PC2 explained 45.63% of the total variation based on all the traits and the genotypes. The GT biplot analysis is a powerful statistical tool for studying relationship among traits, evaluating cultivars based on multiple traits and for identifying those that are superior in certain traits. Few yield related traits, SPAD Chlorophyll Meter Reading (SCMR), harvest index, Leaf Area Index (LAI), Leaf Area Duration (LAD) and protein content had a positive relationship with yield which were recognized as crucial traits for boosting grain yield and nutritional quality. The genotypes ATP-15, ATP-13, ATP-10, ATP-16, ATP-5, ATP-7, ATP-11, ATP-18, ATP-14 and ATP-12 showed superior performance for grain yield as well as other yield contributing traits. Whereas, the genotypes ICHiFe-18, ICHiFe-12, ATP-3, ICHiFe-21, ATP-2, ICHiFe-20, ATP-4, ATP-8, ATP-15, ICHiFe-14, ICHiFe-4, ICHiFe-2 and ICHiFe-5 showed superior performance for nutritional traits. By considering all the studied traits, the genotype ATP-15 was selected as the ideal and most desirable cultivar.

Jiwamrita: A Low Cost Organic Nutrient Source for Growth, Yield and Economics of Organic Mungbean [Vigna radiata (L.) Wilczek] under Changing Agricultural Environment

Aims: To find a suitable alternate option of nutrient management in organic mungbean with standardization of dose and its mode of application.&#x0D; Place and Duration of Study: Agricultural Research Station, Mandor, Jodhpur between July 2020 and October, 2020.&#x0D; Methodology: Treatment comprised of main plots as mode of application: M1: Soil application, M2: Foliar application and M3: Soil and foliar application and sub plots as dose of Jiwamrita: S1: Control, S2: 50 ml/l, S3: 100 ml/l and S4: 150 ml/l were replicated thrice in split plot design. FYM @ 5.0 t/ha was applied on the soil and the field of the experimental site was prepared by disking following harrowing and planking. The crop variety GM 6 was sown on 10th July, 2020 at row spacing of 30 cm with seed rate of 15 kg/ha. The plants were kept at 10 cm distance after thinning at 15 days after sowing. Jiwamrita was prepared using Palekar [1] method (Photo 1) and was kept in shade for 7 days. It was filtered before using for spray as per treatments. It was applied as soil spray at the time of sowing and 15 days after sowing as per treatments of different doses. Foliar application of Jiwamrita was done at 15 and 30 days after sowing as per treatments. Total quantity of solution containing Jiwamrita was 500 liter/ha in all the treated plots. In control plots, a quantity of 500 liter/ha was used as spray. Weeding was done manually at 15 and 30 days after sowing. Data on growth attributes, yield attributes and grain yield was recorded from net plot size of 4 m x 1.8 m and converted into hectare basis. The gross return was computed by multiplying current price of mungbean with yield. The net return was estimated by deducting cost of cultivation from gross return. The benefit-cost ratio was worked out by dividing gross return by cost of cultivation.&#x0D; Results: Maximum plant height of 71.5 cm was recorded with a dose of Jiwamrita @ 150 ml/liter which was at par with Jiwamrita @ 100 ml/liter. The SPAD chlorophyll meter reading (SCMR) of leaves increased at 50 DAS (53.5) being maximum with Jiwamrita @ 150 ml/liter which was significantly higher over SCMR recorded with Jiwamrita @ 50 ml/liter (34.7). The significantly maximum number of pods/plant (28.7) and maximum grain yield (1314 kg/ha) was recorded due to combined application of soil and foliar application of Jiwamrita. Among doses, maximum number of pods (30.9) was recorded under Jiwamrita @ 150 ml/liter which was 30, 24 and 16 percent higher over control and Jiwamrita @ 50, 100 ml/liter. The application of Jiwamrita @ 150 ml/liter resulted in significantly higher grain yield (1221 kg/ha) which was found at par with Jiwamrita @ 100 ml/liter (1179 kg/ha) which were 17 and 13 percent higher, respectively, over control and 9 and 5.6 percent higher, respectively, over Jiwamrita @ 50 ml/liter. The maximum net return ( 65672 ha-1) was recorded with 150 ml/liter followed by 100 ml/liter ( 62686 ha-1).&#x0D; Conclusion: Jiwamrita is a fermented microbial culture which provides essential nutrients to plants. Its application in both soil and plant canopy were found beneficial. The study revealed that twice application of Jiwamrita in soil at the time of sowing and 15 days after sowing and twice application of Jiwamrita as foliar spray at 15 and 30 days after sowing significantly increased the growth attributes, yield attributes and yield of organic mungbean.

The variation of relative water content, SPAD chlorophyll meter reading, stomatal conductance, leaf area, and specific leaf area of Jerusalem artichoke genotypes under different durations of terminal drought in tropical region

AbstractThis work assessed the responses of Jerusalem artichoke (JA) genotypes experienced to different durations of terminal drought for relative water content (RWC), SPAD chlorophyll meter reading (SCMR), stomatal conductance (SC), leaf area (LA) and specific leaf area (SLA), investigated the significant contributor of physiological traits to yield and yield reduction and diversity of physiological traits in terminal drought tolerance genotypes. Field research was conducted during the late‐rainy season for 2 years using a split‐plot design with four replications. The three irrigation treatments involved no‐drought (SD0), short (SD1) and long (SD2) durations of terminal drought were arranged as main plots, and sub‐plots were six genotypes of JA. The current study revealed that RWC, SC, LA, and SLA, were drastically reduced whilst SCMR values slightly increased under SD1 and SD2 compared to SD0. According to multiple linear regression indicated that SLA (SD0), and RWC (SD1 and SD2) had high contributions to tuber fresh weight (TFW), whereas SC had a high contribution to TFW reduction under terminal drought. Principal component analysis also confirmed that the diversity of LA, RWC, and SLA had maximized contributing traits, followed by HI, SCMR and SC in these breeding materials of JA under three irrigation treatments. Our finding emphasized that JA125 (low SLA), HEL256 and JA37 (high SLA) lead to the high performance of TFW under SD0, and they exhibited high TFW under SD1 by performing medium RWC. Likewise, JA4 and JA37 had high TFW under SD2 caused by medium RWC. HEL253 and JA60 were identified as terminal drought‐tolerant genotypes because of performed medium SC, which contributed to a low reduction in TFW. Our promising results are the basis for further studies, SLA, RWC and SC are an important keys for screening drought tolerance (low economic yield reduction) and these genotypes studied could be used for parental lines to improved drought tolerance progenies through breeding programs under different durations of terminal drought‐prone areas.

Photosynthetic and physiological responses to drought of Jerusalem artichoke genotypes differing in drought resistance

Plant physiological and photosynthetic responses to drought among Jerusalem artichoke genotypes possessing different levels of drought resistance are still lacking. We investigated the physiological and photosynthetic responses to drought of six Jerusalem artichoke genotypes differing in drought-resistance levels and evaluated the contribution of physiological and photosynthetic traits to tuber yield under drought condition. The split-plot in randomized complete block design with four replications was used. Six Jerusalem artichoke genotypes as sub-plots were nested in two water regimes (100% ET and 50% ET) as main plots. Relative water content (RWC) was recorded at 30, 60, and 90 days after transplanting (DAT), while SPAD chlorophyll meter reading (SCMR), net photosynthetic rate (Pn), stomatal conductance (gs), and leaf area (LA) were recorded at 30 and 90 DAT. Biomass and tuber yield were recorded at harvest stage. Water deficit restricted RWC by 20.45%, LA by 23.29%, Pn by 9.87, gs by 40.315, biomass by 42.62, and tuber yield by 46.13%, yet increased SCMR (6.74%) of six genotypes. The reductions observed on all traits of drought-resistant genotypes were smaller than that of susceptible genotypes. A drought-resistant genotype KT 50-4 showed a low tuber yield reduction (36.59%) and LA (16.34%) under water deficit condition, whereas KT 50-4, JA 60, and JA 125 had low reductions of Pn (7.06–9.75%) and gs (15.40–42.86%) under water deficit condition. While LA had a significant contribution to tuber yield under fully irrigated (80.11%) and drought (85.57%), Pn and SCMR had smaller contributions to tuber yield under drought condition (3.73% and 12.65%). Our results indicated that improvement of LA could contribute to high tuber yield under limited water conditions.

Effect of water stress on physiological traits of sunflower (Helianthus annuus L.) restorer lines

A field experiment was conducted during rabi, 2018 to evaluate the performance of eight sunflower restorer lines viz., RGP 21-P6, RGP 32-P1, RGP 33-P5, RGP 50-P1, RGP 60-P2, RGP 61-P1, RGP 61-P2 and RGP 95-P1 for physiological traits under water stress conditions in a split-plot design with three replications. Water stress was imposed in stress plots from flowering to harvest. Results indicated that the traits, leaf area index (LAI), total drymatter (TDM), proline accumulation, and crop growth rate (CGR) were more sensitive to moisture stress with above 30% reduction. Whereas, SPAD chlorophyll meter readings (SCMR) was less sensitive with less than 10% reduction due to water stress. Significant decrease and variation was observed among the restorer lines for LAI, SCMR, TDM, relative water content (RWC) andCGR, whereas leaftemperature and proline concentration increased due to water stress. Restorer lines RGP 21-P6, RGP 61-P1, RGP-61-P2, and RGP 95-P1 recorded superiority inLAI, CGR, TDM and leaf temperature among the physiological traits studied even under water stress.

Influence of elicitor molecules on chlorophyll content in groundnut plants challenged with stem rot pathogen (Sclerotium rolfsii) under greenhouse conditions

Groundnut is an important edible oil crop plant whose quality and yield are greatly affected by biotic and abiotic stress. The process ofmechanisms ofrecovery fromstress are also critical to its productivity, but are currently poorly characterized. The present investigation was carried out to understand the ability of different elicitors (piperine, reserpine and b-sitosterol) to induce resistance against stress in groundnut. The chlorophyll content in groundnut leaves was measured using SPAD chlorophyll meter following the seed treatment, foliar application and micro-injection of phytochemicals. The SCMR (SPAD chlorophyll meter reading) of phytochemical-treated plants was found to be more in comparison with the untreated plants. All the three phytochemicals were found to be effective in increasing the chlorophyll content in groundnut leaves. MaximumSCMR (42.14) was observed in plants treated with piperine through foliar application method.

Correlation and path coefficient analysis for yield, yield components and water use efficiency traits in blackgram under organic fertilizer management

Correlation and path co-efficient analysis was carried out for yield, yield component and water use efficiency traits among 30 blackgram genotypes under organic fertilizer management. Correlation studies indicated that seed yield per plant showed highly significant and positive correlation with harvest index, followed by number of primary branches per plant, number of pods per plant. It exhibited significant negative correlation with SCMR (SPAD chlorophyll meter reading) at 35 DAS and SLA (Specific leaf area) at 50 DAS at both phenotypic and genotypic levels. Path Analysis revealed that harvest index exhibited high and positive direct effect on seed yield per plant followed by number of pods per plant and number of primary branches per plant. SCMR (SPAD chlorophyll meter reading) at 35 DAS and SLA (Specific leaf area) at 50 DAS plant exhibited low and negative direct effects on seed yield per plant. Hence selection based on these traits would be effective in increasing the seed yield and improving water use efficiency. Opting for genotypes with low to moderate SLA (Specific leaf area) readings and high SCMR (SPAD chlorophyll meter reading) at flowering stage would increase water use efficiency under organic fertilizer management.

Genetic variability for key physiological traits in groundnut under managed drought condition

Drought is a major production constraint in rainfed groundnut. In the present study, genetic variability forrelative water content (RWC) of leaf, membrane stability index (MSI), SPAD chlorophyll meter readings (SCMR) and percent wilted plants was assessed in 40 advanced breeding lines of groundnut under managed drought condition. Significant differences were noticed for key physiological traits. The RWC of leaf, MSI and percentage of wilted plants under drought showed high GCV, PCV, heritability coupled with high genetic advance over mean. The SCMR showed lower GCV and PCV but exhibited high heritability with moderate genetic advance over mean indicating the possibility to improve this trait by proper selection methods.