Normal Irrigation Conditions Research Articles

Influence of cut-off irrigation on seed quality and physiological indices of various safflower (Carthamus tinctorius L.) genotypes

Safflower (<em>Carthamus tinctorius</em> L.) is an oilseed crop adapted to arid and semiarid regions. In this study, an experiment was performed to evaluate the effects of water deficiency on plant height, 1,000-grain weight, seed yield, harvest index, relative water content (RWC), oil yield, and oil content in 15 safflower genotypes. A split-plot randomized complete blocks design was arranged with three replications. Safflower plants were grown under normal irrigation and water deficit conditions in Sarvestan, Fars Province, Iran during 2016 and 2017 growing seasons. Combined analysis results indicated that water deficit stress had negative effects on all measured indices. Average seed yield declined by 65.91% (2,337.91 to 796.79 kg ha<sup>−1</sup>) due to water deficit stress. Genotype also had a significant effect on evaluated indices, and the interaction between genotype and irrigation significantly influenced all indices except plant height. Under both conditions, highest RWC, seed yield, and oil yield were observed in Dincer and PI-537598 genotypes. Maximum plant height and 1,000-seed weight in both irrigation conditions were observed in the Dincer genotype. In the normal irrigation condition, maximum harvest index and oil content were observed in the CW-74 genotype. Thus, Dincer and PI-537598 were classified as the best genotypes (based on seed yield, RWC, and oil yield) under both normal irrigation and water deficit stress conditions.

The Role of Sewage Irrigation Management in Water Productivity, Growth and Yield Parameters of Broccoli in Al-Sulaimani government/Kurdistan region

The objective of the present work was to estimate water requirements and water use efficiency for Broccoli under normal irrigation conditions and sewage irrigation. Field experiment was carried out during the season 2018 at station/Sulaimni agricultural station/Bakrajo –College of Agricultural Sciences. The experiment included three treatments: River water irrigation in all season growth (I1), Sewage water irrigation in all season growth (I2), Alternate irrigation (one river irrigation followed by two sewage water irrigation) in all season growth (I3). The experimental Design was Randomized Complete Block Design (RCBD) with three replications. Broccoli planted under surface irrigation system. Mean irrigation requirement for irrigation management scheduling gave water consumptive use values 442, 432 and 427 mm for river water, sewage water and alternate irrigation, respectively. Average yield Broccoli plant was 32.67, 40.25 and 46.73 Ton ha−1 for river water irrigation, sewage water irrigation and alternate irrigation, respectively. High performance of Alternate irrigation application was mentioned by plant height which record 39, 42 and 46 cm; head diameter 21, 25 and 28 cm; leaf area 306, 329 and 349 cm2 and number of leaves 18, 21 and 22 for river water irrigation, sewage water irrigation and alternate irrigation, respectively. WUEc were 7.39, 9.32 and 10.94 kg m−3 for river, sewage and alternate treatments, respectively. The results showed that the concentrations of these elements did not reach the critical limits in the fruits for all irrigation treatments. This is a positive and good result due to the increase in rainfall rates in this season led to weak accumulation of heavy metals in the soil and poor absorption by the plant.

Assessment of Selected Landrace and Improved Groundnut (Arachis hypogaea L.) Genotypes under Stressed and Non-stressed Conditions

Drought is one of the most essential and critical abiotic restraints to groundnut production and yields in the Northern Region of Ghana. A field experiment was conducted to assess selected landrace and improved groundnut genotypes for agronomic performance in the 2017 and 2018 minor seasons. Groundnut genotypes were treated under normal irrigation (W/W) and water-stressed (W/S) conditions. A Randomized Completely Block Design (RCBD) with four replications was adopted. Total experimental area was 23.4m x 2.4 m with a planting distance of 40 cm x 20 cm for both environments. Data collected include; days to 50% emergence and flowering, plant height at maturity (cm), growth appearance, days to maturity, number of pods/plot, number of seeds/plot, pod weight (g), seed weight (g), fresh and dry biomass weights (g), SPAD chlorophyll meter reading at 60 and 80 days after planting, harvest index (HI) and drought tolerance index (DTI). The data were subjected to analysis of variance (ANOVA) using GenStat, version 12.0, Exploratory Analysis, descriptive Statistics (mean comparison of plant characteristics by varieties at 5% level using Tukey’s groups) was conducted; Correlation Analysis and Multivariate Analyses were performed using the Wilk’s Lambda to test for significant difference at 5% and 1% levels respectively. Means were separated using S.E.D. of means at 95% confidence level. Results from the growth features indicated a higher percentage of the groundnut varieties sprouted earlier under well-watered conditions. There was no significant difference among the groundnuts regarding the numbers of days to flowering. The groundnuts took approximately 104 days after planting to mature under both water conditions. Chlorophyll content and distribution in the groundnut leaves was high the well-watered plants. The chlorophyll content among the groundnut crops showed no significant difference between the chlorophyll content at 60-days after planting and 80-days after planting under the water-stressed condition. However, chlorophyll content of leaves at the 60-days after planting was 2.94 lower than that under 80 days after planting. Maturity and flowering (0.768), as well as plant height and seed yield (0.501) were highly significantly and highly positively correlated. The seed characteristics were also highly, significantly and positively correlated with the pod characteristics of the crop. The biomass measure also correlated with the pod and seed traits. Groundnuts genotypes under well-watered environment generally performed better in terms of yield than those under water-stressed environment.

Genotype selection for physiological responses of drought tolerance using molecular markers in polycross hybrids of orchardgrass

AbstractThe present study aimed to assess the effect of contrasting levels of molecular and phenotypic diversity among polycross parents of orchardgrass on the performance of synthetic progeny with respect to physiological responses and drought tolerance. Four polycross groups each composed of six parental plants were evaluated under normal irrigation and drought stress conditions. A number of 923 inter simple sequence repeats and sequence related amplified polymorphism markers and several phenotypic traits were used to select contrasting levels of diversity (high and low) in parental genotypes. Highly significant correlation was observed between molecular distance and progeny performances at both normal irrigation and drought stress conditions. High molecular diversity among polycross parents led to a significant yield advantage of first generation progeny with averages of 34.40% for normal irrigation and 48.10% for drought stress conditions. Also crosses between genetically distant parents produced progeny with considerable drought tolerance and yield stability. Positive associations between phenotypic distance of parents and progeny performance were found for most physiological traits at both moisture regimes but phenotypic distances had weak association with forage yield, stress tolerance index and yield stability of progeny. Significant associations between drought tolerance index and some physiological traits confirmed the importance of these traits in conferring drought tolerance of orchardgrass. Our results underscore the effectiveness of marker‐assisted polycross breeding to improve drought tolerance and yield stability through physiological traits in orchardgrass.

ASSOCIATION MAPPING OF MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS OF FLAG LEAF RELATED TO DROUGHT TOLERANCE IN BARLEY

Association mapping has proven to be a powerful approach for dissecting the genetic basis of complex traits. In this study, QTLs controlling flag leaf characteristics under drought stress were detected in a set of 148 modern spring barley cultivars using AM analysis. Flag leaf length (FLL), flag leaf width (FLW), relative water content (RWC), chlorophyll content, and maximum quantum efficiency of PSII (Fv/Fm) which are important in photosynthetic rate, were evaluated under normal irrigation and drought stress conditions at grain filling stage. Population structure was estimated using Structure 2.3 and linkage disequilibrium (LD) was estimated by the ‘Full Matrix LD’ using Tassel 5.0 . Significant marker/trait associations were investigated based on K-Q matrix using Tassel 3.0 . The analysis of population structure divided the cultivars into two sub-groups. Significant LD values (P < 0.01) between polymorphic sites with regions of high and low LD were observed. A total of 84 significant putative genomic regions were identified, which delineated into 37 QTLs under two water treatments. Two stable QTLs on 2H and 3H were detected for FLL in drought stress treatment. A QTL for FLL were detected on 2H in normal treatment, which alone explained around 11% of phenotypic variance of FLL. This QTL was also associated with the expression of FLW and explained around 7.5% of phenotypic variance. The results suggest that major loci are located on chromosomes 2H, 3H, 4H and 5H involved in the development of flag leaf characteristics and could be used as selection criteria in barley breeding for drought tolerance.

Association between seed yield-related traits and cDNA-AFLP markers in cumin (Cuminum cyminum) under drought and irrigation regimes

Cumin (Cuminum cyminum L.) is an aromatic medicinal herb with beneficial essential oil being used in antibacterial activities and industry of creams, lotions, and perfumes. Use of functional markers expedites breeding cumin for drought tolerance. The objective of this study was to identify association of plant height and several seed yield- related traits with complementary DNA-amplified fragment length polymorphism (cDNA-AFLP) markers in 15 cumin (Cuminum cyminum) accessions under normal irrigation (NI) and drought stress (DS) conditions. Cumin accessions were grown in the field and subjected to NI practice and post-heading DS in two years in Kerman, Iran. The mean seed yield ranged between 448.72 and 994.18 kg/ha in NI and was from 211.05 to 452.05.06 kg/ha in DS. Reduction in plant height and seed yield-related traits ranged 27–28% in the first and 29–50% in the second year in DS compared with NI. Twelve EcoR I-Mse I primer combinations were used to amplify AFLP markers in cDNA fragments isolated from RNA samples. The identified markers were subjected to analysis of marker-trait associations (MTAs) using the generalized linear model (GLM) and mixed linear model (MLM). A number of 239 and 208 reliable transcript-derived fragments (TDFs) were amplified in cumin genotypes tested in NI and DS, respectively. Of the identified TDFs, highly significant markers were used for association analysis, only. Higher number of MTAs was identified for traits in NI compared with DS. Of the identified linked markers, 5 in NI and 3 in DS were significantly associated with more than one trait under two water status conditions. None of markers were identified as common MTAs between the two moisture conditions. Analysis of population structure demonstrated cumin accessions could be divided into 3 and 4 sub-populations. Overall, high variation was identified in cumin with respect to biological yield, seed yield and seed related traits and the identified linked markers can be incorporated into marker-assisted selection programs for the improvement of seed yield in drought condition.

Association of biochemical traits with grain yield in triticale genotypes under normal irrigation and drought stress conditions

Association of biochemical traits with grain yield in triticale genotypes under normal irrigation and drought stress conditions

Response of quantitative and physiological traits to drought stress in the SeriM82/Babax wheat population

Assessment of quantitative traits in bi-parental progenies provides a strategy to identify drought tolerant genotypes and stress-adaptive traits in wheat. A recombinant inbred line (RIL) population with 167 lines produced from the SeriM82/Babax cross was subjected to normal irrigation and drought stress (at the heading stage) under field conditions. The study was done in Bajgah, Shiraz, Fars province, Iran, during three consecutive seasons. Shiraz is located in a temperate, major wheat production region of Iran that is prone to periodic drought. The aims of this study were to identify drought tolerant RILs and drought adaptive traits. The mean grain yield was 237.91 and 148.60 g m−2 under normal irrigation and drought stressed conditions, respectively. Above 48.0% reduction in grain yield was observed under drought stress in the three consecutive growing seasons. Several RIL lines had high grain yield under both moisture regimes. The mean leaf relative water content (RWC) was 0.4 under drought condition. One RIL had relatively high RWC and grain yield under both treatments. Heritability of several traits did not change between the two moisture conditions whereas it was reduced for few of traits. Assessment of the interrelationship of traits showed that RWC, days to heading, awn length and spikelets per spike were the main contributors to grain yield that became more important under drought conditions. Given the relatively high heritability values estimated under both conditions and strong association with grain yield, these drought adaptive traits could be used for indirect selection to improve drought tolerance in this region of Iran. Overall, information of the identified drought adaptive traits and RILs lay foundation for the improvement of drought tolerance in wheat.

Oxidant related biochemical traits are significant indices in triticale grain yield under drought stress condition

Two separate experiments, one as drought stress conditions and the other one as the normal irrigation conditions based on randomized complete block design with three replications were implemented to examine 20 triticale (Triticoseclae wittamack X) genotypes of which 19 genotypes have recently been generated by crossing different parent lines and the other one was Javaniloo, a common cultivar. Based on the results of different statistical techniques and comparing relationships among traits for normal irrigation and stress condition, enzymatic antioxidant could be used as criteria for screening tolerant genotypes of triticale. On the other hand, it is pointed out that superoxide dismutase are the most important criteria to achieve higher tolerant genotypes through indirect selection. Furthermore, hydrogen peroxide and malondialdehyde content having high relationship with rain yield are also the different possible criteria for screening triticale genotypes for water stress conditions in which genotypes with lower content of these traits could be screened.

Effect of Drought–Flood Abrupt Alternation on Rice Yield and Yield Components

The purpose of this paper is to clarify the compensation or reduction effect of drought–flood abrupt alternation (DFAA) events on the yield and yield components of rice (Oryza sativa L.). The experiments, conducted in 2016 and 2017, were on three different drought and flood treatments and compared with normal irrigation conditions. Compared with the normal control group, the average yield reduction of the DFAA groups was 12.98% in 2016 and 29.94% in 2017, and the combination of heavy droughts and heavy flooding was the most unfavorable for yield. The reduction in grains per panicle and the total grain number was the main reason for yield reduction under DFAA stress. The damage in terms of the total grain number amounted to 18.84 and 17.82% in 2016 and 2017, respectively. The interannual differences in the thousand‐seed mass and seed setting rate increased in 2016 and decreased in 2017. Compared with the drought groups and the flood groups, the flood stress of the DFAA groups reduced the yield under drought conditions, and the decrease in the total grain number and panicles per barrel during the flood period was the main reason. The drought stress of the DFAA groups compensated the yield under flood conditions, mainly because the total grain number and seed setting rate increased during the drought period. Under long‐term light drought conditions, the panicles per barrel, grains per panicle, total grain number, thousand‐seed mass, and seed setting rate increased. Under long‐term heavy drought conditions, the panicles per barrel mainly increased.

Drought Screening and Supplemental Irrigation Management for some Rice Cultivars in Drought Prone Area of Bangladesh

Water stress is one of the limiting factors for rice production. Under rainfed condition with erratic rainfall, water stress becomes a serious threat for sustainable rice production. Drought tolerant cultivars along with appropriate management practices can solve the problem. Field and control condition studies were carried out to study the response of some rice cultivars to water-stress, and to develop appropriate on-farm management strategy for sustainable yield under drought condition. The results revealed that most of the cultivars produced good yield under drought condition compared to normal irrigated condition (under control condition and field study). Levee management strategy (of height of 20 cm) seems a viable option to alleviate the effect of drought under field condition. Levee management and life-support supplemental irrigation (when necessary) can facilitate good yield of most of the cultivars. These cultivars seemed to be appropriate for cultivation in drought-prone areas.

Mitigating the effect of drought stress on yield in wheat (Triticum aestivum) using arbuscular mycorrhiza fungi (Glomus mosseae)

The arbuscular mycorrhiza fungus (AMF) (Glomus mosseae) is a beneficial microorganism used in agriculture as an efficient tool to improve plant growth and nutrition by inducing symbiotic association with crops. The present investigation was conducted to study the contribution of arbuscular mycorrhizal fungus to drought tolerance in wheat (Triticum aestivum L.) grown under normal irrigated conditions and in water stress created by withholding irrigation at jointing and heading stage under net house environment. Wheat seeds of two wheat varieties WH 1025 and WH 1105 were grown in pots after treatment with or without the AMF. Under water stress conditions, the wheat variety WH 1025 performed better in terms of growth and yield attributes as compared to WH 1105. The results obtained showed a significant improvement by AMF on plant height, number of productive tillers, spike length, number of spikelet, grain/spike, grain weight/spike and test weight under both irrigated and drought stress condition. Biomass and grain yields were higher in plants treated with mycorrhiza than non-mycorrhizal plants of both the varieties irrespective of soil moisture. Therefore, the results suggest that mycorrhizal inoculation play a vital role in improving growth and yield in wheat by reducing the effects of drought stress and sustain the wheat crop under the semi-arid environments.

Influence of Field Soil Drought Stress on Some Key Physiological, Yield and Quality Traits of Selected Newly-Developed Hexaploid Bread Wheat (Triticum aestivum L.) Cultivars

Drought is one of the commonly occurring environmental stresses, limiting crop production in many countries. Selection of cultivar is the most effective and economical means for alleviating the adverse effects of drought stress on crops. The present study aimed to investigate the growth, some physiological processes, yield and quality of some newly-developed wheat cultivars (AARI-2011, AAS-2011, Faisalabad-2008, Millat-2011 and Punjab-2011) under field drought stress conditions. The cultivars were sown in a field under normal irrigation and drought-induced conditions. Maximum net photosynthetic rate was recorded in cv. AAS-2011 at growth stage of 67 days after wheat emergence under normal irrigation and cv. Faisalabad-2008 at 67 days after wheat emergence under drought condition. Leaf stomatal conductance and transpiration rate were maximum in cv. Faisalabad-2008 under drought conditions. The adverse effects of drought stress were observed more on cv. Millat-2011 than Faisalabad-2008, with respect to net photosynthetic rate and transpiration. Drought exerted a significant adverse effect on leaf stomatal conductance at 74 days after wheat emergence which was recorded as 230 mmol m-2 s-1. Among the cultivars, AAS-2011 recorded maximum yield traits and grain yield under normal irrigation condition and Faisalabad-2008 under drought condition. Cultivar Millat-2011 was the most susceptible to drought and Faisalabad-2008 the most resistant to drought. Faisalabad-2008 maintained the quality at the most under drought stress conditions. It is concluded that Fasialabad-2008 should be grown under field drought conditions to achieve maximal yield and quality of wheat.

Genotype\u2009\xd7\u2009Environment interactions of Nagina22 rice mutants for yield traits under low phosphorus, water limited and normal irrigated conditions

Multi environment testing helps identify stable genotypes especially for adverse abiotic stress situations. In the era of climate change and multiple abiotic stresses, it becomes important to analyze stability of rice lines under both irrigated and stress conditions. Mutants are an important genetic resource which can help in revealing the basis of natural variation. We analyzed 300 EMS induced mutants of aus rice cultivar Nagina22 (N22) for their G × E interaction and stability under low phosphorus (P), water limited and irrigated conditions. Environmental effect and interaction were more significant than genotypic contribution on grain yield (GY), productive tillers (TN) and plant height (PH) under these three environmental conditions in dry season, 2010. GY and TN were more affected by low P stress than by water limited condition, but PH was not significantly different under these two stresses. Mutants G17, G209, G29, G91, G63 and G32 were stable for GY in decreasing order of stability across the three environments but G254 and G50 were stable only in low P, G17 and G45 only in water limited and G295 and G289 only in normal irrigated condition. We then selected and evaluated 3 high yielding mutants, 3 low yielding mutants and N22 for their stability and adaptability to these 3 environments in both wet and dry seasons for six years (2010–2015). The most stable lines based on the combined analysis of 12 seasons were G125 (NH210) under normal condition, G17 (NH686), G176 (NH363) and G284 (NH162) in low P condition and G176 (NH363) under water limited condition. G176 was the best considering all 3 conditions. When screened for 15 Pup1 gene-specific markers, G176 showed alleles similar to N22. While two other low-P tolerant lines G17 and G65 showed N22 similar alleles only at k-1 and k-5 but a different allele or null allele at 13 other loci. These stable mutants are a valuable resource for varietal development and to discover genes for tolerance to multiple abiotic stresses.

Differential growth, yield and biochemical responses of maize to the exogenous application of Kappaphycus alvarezii seaweed extract, at grain-filling stage under normal and drought conditions

Maize is sensitive to water stress at flowering and grain-filling stages and thus strategies for the mitigation of stress and improving the yield sustainably would be beneficial. Two factorial pot experiments were carried out to assess the efficacy of a biostimulant product obtained from Kappaphycus alvarezii in conjunction with recommended rate of fertilizers (RRF), in mitigating moderate and severe stress in maize. The plants were subjected to normal as well as water deficit conditions following which Kappaphycus alvarezii seaweed extract (KSWE) was applied foliarly only once at the grain-filling stage along with a suitable control (water spray + RRF). Growth and yield parameters along with antioxidant enzymes, metabolites and reactive oxygen species content in leaves were studied. The results revealed that water deficit conditions (moderate and severe) significantly (p < 0.001) reduced the yield in both the trials, by 22 and 74% as compared to plants receiving the normal irrigation schedule, while KSWE increased the yield by 14% and 23% (p < 0.01), respectively. KSWE applied once at the grain-filling stage increased seed yield only under normal condition and not under stress conditions in both the seasons. The increase in seed yield observed under the KSWE treatments was predominantly through the increase in all the yield attributes, especially, cob length, the number of grains per cob and length of grain fill, however, the 100-seed weight remained unaltered. Increased activities and concentrations of enzymatic and non-enzymatic antioxidants due to KSWE application with concomitant reduction in reactive oxygen species, such as O2− and H2O2 levels, both under normal and stressed conditions, resulted in a lesser degree of oxidative stress in KSWE treated plants. Thus, the results revealed that a single application of KSWE, even at a late crop stage can be beneficial under normal irrigated condition.

GENETIC VARIATION AND INTERRELATIONSHIPS AMONG AGRONOMIC TRAITS IN BREAD WHEAT GENOTYPES UNDER WATER DEFICIT AND NORMAL IRRIGATION CONDITIONS

Water deficit is one of the major stresses that reducing wheat production particularly under current climate change. The aim of this study was to investigate the genotypic variation of thirty bread wheat genotypes under water deficit and normal irrigation conditions. In addition, to clarify the association between grain yield and the other important agronomic traits, and to determine the interrelationships among the tested traits under both conditions. Two field experiments were carried out in New Valley, Agricultural Research Station conditions, Agricultural Research Center, Egypt during 2014-2015 and 2015-2016 growing seasons. Thirty bread wheat genotypes were evaluated under two irrigation regimes. The normal irrigation was used every 15 days (NI) with total nine irrigation times per season (2900 m3/fad.). The other irrigation regime was applied every 30 days giving in total five irrigation times (1900 m3/fad.) providing water deficit conditions (WD). The experimental design was laid out in a spilt-plot in which irrigation treatments were in the main plots and genotypes were randomized in the sub-plots, in three replications. All evaluated traits were affected significantly by irrigation treatments. The genotypes; G1, G2, G17, G21, G22, G23, G24 and G27 exhibited good grain yield/plant and its components under both conditions. Tolerance indices; mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI) and yield index (YI) were calculated based on grain yield/plant under both conditions. The highest indices were observed for G21, G2 and G1 genotypes followed by G23, G27 and G24 genotypes. Based on these indices, the genotypes were classified into three groups A (drought tolerant), B (moderate drought-tolerant) and C (drought-sensitive) with 8, 18 and 4 genotypes, respectively. Furthermore, phenotypic and genotypic correlation coefficients were estimated and it was observed strong and significant positive correlation between grain yield and 100-grain weight, grain weight/spike, biological yield/plant and harvest index under both conditions. Additionally, path analysis was calculated and it was found that biological yield and harvest index exhibited the highest positive direct effect on grain yield under both conditions. On the other hand, the highest indirect effects on grain yield were assigned for number of spikes/plant followed by flag leaf area, grain weight/spike and 100-grain weight under both conditions. Which demonstrates the importance of these traits in improving grain yield under both conditions.

Performance of potato (Solanum tuberosum) advanced hybrid MS/6-1947 under high temperature stress and water deficit conditions

In present investigation, potato (Solanum tuberosum L.) advanced stage hybrid MS/6-1947 was evaluated along with controls under high temperature and water stress regimes for three successive winter crop seasons. Under high temperature at Modipuram, MS/6-1947 (13.3 t/ha) showed yield enhancement of 20, 9 and 11% over the controls Kufri Bahar, Kufri Pukhraj and Kufri Surya. It also exhibited at par tolerance to hopper with Kufri Surya and damages due to mite burn were lower than Kufri Bahar and Kufri Pukhraj. The hybrid possessed 18% tuber dry matter. Results ondrought toleranceat Modipuram revealed superior performance of MS/6-1947 under normal irrigation, mild water and severe water stress conditions as compared to best control Kufri Pukhraj as yield reduction was comparatively lower under mild and severe water stress treatments. Drought tolerance index (DTI) values were maximum in MS/6-1947 (1.02 and 0.79) followed by Kufri Pukhraj (0.86 and 0.51) and Kufri Bahar (0.72 and 0.58) under mild and severe water deficit treatments, respectively. Drought tolerance studies at Jodhpur revealed better performance of MS/6-1947 under normal and mild water stress conditions as compared to the controls Kufri Pukhraj and Kufri Surya as yield reduction was comparatively lower under mild water stress conditions. DTI values were maximum in MS/6-1947 (1.08) followed by Kufri Puhkraj (1.01) and Kufri Surya (0.41) under mild water deficit treatment. Tuber dry matter content increased under water stress over normal irrigation at both the locations. MS/6-1947 is suitable for table potatoes. MS/6-1947 may be a better option for integrating in cereal based crop sequences, for exploiting its yield potential in early season and for attaining sustainable productivity in areas where high temperature and lower water availability are constraint for raising the successful potato crop.

Characterization of backcross introgression lines derived from Oryza nivara accessions for photosynthesis and yield.

Improvement of photosynthetic traits is a promising strategy to break the yield potential barrier of major food crops. Leaf photosynthetic traits were evaluated in a set of high yielding Oryza sativa, cv. Swarna × Oryza nivara backcross introgression lines (BILs) along with recurrent parent Swarna, both in wet (Kharif) and dry (Rabi) seasons in normal irrigated field conditions. Net photosynthesis (P N) ranged from 15.37 to 23.25µmol (CO2) m-2s-1 in the BILs. Significant difference in P N was observed across the seasons and genotypes. Six BILs showed high photosynthesis compared with recurrent parent in both seasons. Chlorophyll content showed minimum variation across the seasons for any specific BIL but significant variation was observed among BILs. Significant positive association between photosynthetic traits and yield traits was observed, but this association was not consistent across seasons mainly due to contrasting weather parameters in both seasons. BILs 166s and 248s with high and consistent photosynthetic rate exhibited stable high yield levels in both the seasons compared to the recurrent parent Swarna. There is scope to exploit photosynthetic efficiency of wild and weedy rice to identify genes for improvement of photosynthetic rate in cultivars.

Correlation, path and regression analysis in some bread wheat genotypes under normal irrigation and drought conditions

THE OBJECTIVE of this study was to assess correlation, path and regression analysis in 39 F6 bread wheat (Triticum aestivum L) genotypes during two seasons, i.e., 2015/2016 (F7) and 2016/2017 (F8) under irrigation and drought stress conditions at Fac. Agric. Edu. Farm, Minia University, Egypt. A positive correlation was found between grain yield and each of the number of spikes/plant and number of grains/spike under the two conditions. Path analysis revealed high positive direct effects on grain yield/plant via the number of grains/spike (0.929) under irrigation and number of spikes/plant (0.973) under drought. The direct effect of 100-grain weight on grain yield/plant was positive under irrigation (0.649) and drought (0.260). The indirect effects of these traits were negative under the two conditions. Stepwise regression analysis revealed that three models no. 8, 9 and 10 were fitted for each environment. The model no. 8 included one trait; the number of grains/spike under irrigation and number of spikes/plant under drought. Its relative contributions in grain yield were 0.180 and 0.693 under irrigation and drought; respectively. The model no. 9 in the two environments included two traits; the number of grains/spike and number of spikes/plant, its relative contributions in grain yield/plant were 0.544 and 0.836 under normal and drought conditions, respectively. The model no. 10 included three traits number of grains/spike, number of spikes/plant and 100-grain weight, its relative contribution in grain yield/plant were 0.0.931 and 0.978 under normal and drought conditions, respectively. This model no. 10 is fit and superior to use in selection for grain yield/plant.

Evaluation of agro-morphological traits related to grain yield of Iranian wheat genotypes in drought-stress and normal irrigation conditions

Evaluation of agro-morphological traits related to grain yield of Iranian wheat genotypes in drought-stress and normal irrigation conditions