Rain-fed Conditions Research Articles

Wheat breeding for early heading: Does it improve grain yield under drought stress and well-watered conditions?

Terminal drought stress strongly affects wheat grain yield under Mediterranean conditions. Therefore, developing early-heading bread wheat cultivars in these conditions is an important breeding strategy. In the present research, earliness was transferred from the Australian cultivar, Excalibur, to three Iranian cultivars, Roshan, Kalheydari and Mahdavi, in separate backcross (BC) breeding programs from 2012 to 2018. The earliest and latest heading genotypes of each BC 3 population, were selected as near-isogenic lines (NILs). NILs and their parents were assessed under diverse field conditions including rain-fed, moderate drought stress and well-watered conditions in three locations, Kerman, Sepidan and Semirom, during two growing seasons, 2018–2019 and 2019–2020. Breeding for early heading significantly improved earliness in all genetic backgrounds and increased grain yield by 36.4% and 9.6%, in the rain-fed and moderate drought stress conditions, respectively. Whereas, grain yield was not significantly affected by early heading under well-watered conditions. Results showed that breeding for early heading, a highly heritable trait, is an appropriate method to increase grain yield and reduce water consumption under drought stress and well-watered conditions, respectively. Based on these findings, we recommend transferring early heading to high yield late heading commercial cultivars using backcrossing. • For the first time, near isogenic lines of early heading were developed. • Breeding for early heading increased grain yield by 36.4% in rain-fed conditions. • Early heading increased grain yield by 9.6% in moderate drought stress conditions. • Early heading did not affect grain yield under well-watered conditions in Kerman.

Effect of Organic Management on Growth, Yield and Economics of Green Gram, Pigeon Pea and Sunflower under Rainfed Conditions

A field experiment was conducted during Kharif, 2021 at Gungal (around 43 km from Hyderabad) Research Farm of ICAR-Central Research Institute for Dryland Agriculture, Hyderabad, India. The soil was Sandy clay loam in texture, slightly acidic in reaction, low in organic carbon, available nitrogen, available phosphorus and medium in available potassium. The experiment was laid out in a randomized complete block design with three treatment combinations viz., Organic (recommended 100% N equivalent FYM), Integrated (recommended 25% N equivalent FYM + 75% N and 100% P and K through chemical fertilizers) and Control (recommended 100 % NPK through chemical fertilizer) replicated nine times. Based on the results, it was found that the growth, yield attributes, yield, and economics with respect to all the three crops viz., green gram, pigeon pea and sunflower were significantly higher with organic treatment which was followed by integrated treatment and control.

Efficiency of foliar fertilization for the improvement of pomological parameters, mineral composition, carbohydrates status and polyphenols components in olive fruit cultivar Chemlali

Foliar fertilization in rain-fed olive orchards is used nowadays in order to improve the yields for the olive oil industry. The present work aimed to study the effect of foliar fertilization on the quality parameters of olive fruits. Three foliar fertilizers and biostimulants were applied on Chemlali olive cultivar, cultivated under rain-fed conditions in the center of Tunisia, at different stages from the vegetative cycle during two successive years. Six treatments formed the fertilization program: F1 (rich in nitrogen), F2 (rich in boron), F4 (a biostimulant rich in calcium), F3 (supplying an addition of F1 and F2), F5 (supplying an addition of F1, F2 and F4) and a control (without foliar fertilization). At the end of the experiment during the year 2015, fruits were harvested, freeze-dried and the characteristics of drupes and chemical composition of the fruits were evaluated: mineral composition, carbohydrates profile and individual polyphenols. Results showed that some treatments especially rich in Ca improved the fruit size. Foliar fertilization induced differences in the mineral content of fruits. Regarding carbohydrates, glucose was the main sugar present in the fruits and varied between 8.8 μg/mg dry weight (d.w) and 36.43 μg/mg (d.w.). Changes were clearly observed in the pool of the phenolic fraction. The combined treatment F5 showed the highest concentrations in oleuropein and hydroxytyrosol and were equal to 742.6 and 112.94 μg/g of fresh weight respectively. This work is of great interest because it showed the role of nutrients supply in improving the quality of olive fruits.

Impact of Plant Growth-Promoting Rhizobacteria Inoculation on the Physiological Response and Productivity Traits of Field-Grown Tomatoes in Hungary

Drought-tolerant plant growth-promoting rhizobacteria (PGPR) may promote plant development under limited water supply conditions, when plant’s water demand is not completely satisfied under rain-fed conditions or when irrigation water availability is limited. The aim of this study was to examine the effects of two inoculation treatments (B2: Alcaligenes sp. 3573, Bacillus sp. BAR16, and Bacillus sp. PAR11 strains and B3: Pseudomonas sp. MUS04, Rhodococcus sp. BAR03, and Variovorax sp. BAR04 strains) and compare those to a control (B0) without artificial inoculation on chlorophyll fluorescence, leaf chlorophyll content (SPAD value), canopy temperature, and the yield of the processing tomato cultivar H-1015 F1 grown under field conditions. The young seedlings of the hybrid tomato variety H-1015 F1 were immersed in 1% of B2 or B3 products (BAY-BIO, Szeged Hungary) for 5 min. Inoculated and untreated seedlings were grown under three irrigation treatments [regular irrigation (RI), deficit irrigation (DI), and no irrigation (I0)], to reveal the effect of PGPR under different levels of water stress. In the dry year (2018), higher canopy temperature and chlorophyll fluorescence (Fv/Fm) were measured during flowering in plants treated with bacteria than in untreated plants. In the stage of flowering and fruit setting, the B3 treatment led to a significant decrease in the Fv/Fm value, canopy temperature remained high, and the SPAD value was statistically the same in all treatments. Under limited water supply, in most cases, PGPR led to a significantly greater total yield but more unripe green berries compared to untreated plants. Under moderate water shortage (dry year + deficit irrigation), the B3 treatment resulted in 26% more ripe, marketable fruit and 49% less unripe fruit compared to the B2 treatment. On the other hand, in the wet year (2020), the bacterial treatments generally did not affect physiological properties, though the B2 treatment produced a higher marketable yield while the amount of green and diseased fruits did not differ statistically, compared to the B3 treatment under deficit irrigation. Based on our study, we recommend the application of the B3 PGPR product as it positively affected key physiological processes, leading to a higher marketable yield particularly under water shortage.

Productivity and Quality of Fodder Crops under Late-sown Conditions in Semi-arid Tropics of India

Background: In India, agriculture and animal husbandry are inextricably linked and are essential for livelihood security. Despite the fact that India has the world’s largest livestock population, feed and fodder supply is under huge strain, especially as area accessible for fodder cultivation has been shrinking. During the months of March-May and November-February are known as lean periods of fodder production, the supply of green fodder is limited throughout the year in a rainfed condition. Fodder crops develop swiftly and cover the ground surface quickly, even in low-rainfall conditions, producing a significant amount of green fodder while also providing vegetative cover over the land, resulting in resource conserving as well as increased productivity. In this context, the current study was conducted to evaluate various fodder crops, assess their productivity and quality and make appropriate recommendations for semi-arid tropics of India. Methods: Field experiments were carried out for three years from 2015-16 to 2017-18 at the Agricultural Research Station, Ananthapuramu andhra Pradesh, India, which is located between 14°41'N Latitude and 77°40'E Longitude and an altitude of 350 m. above mean sea level, which falls under the Semi-Arid Tropics. The experiment was laid out in a randomized block design with nine treatments (fodder crops) and three replications. The treatments comprised of different fodder crops viz., fodder sorghum, fodder maize, fodder bajra, clusterbean, fodder cowpea, field bean, brown top millet, horse gram and sunhemp. Result: The current study concludes that fodder bajra, fodder sorghum and fodder maize are potential forage cereals because they can produce more quantity and quality fodder while also ensuring net monetary returns and fodder cowpea and sunhemp are the next best suitable forage legumes under late-sown conditions in the semi-arid tropics of India.

Perennial alley cropping contributes to decrease soil CO2 and N2O emissions and increase soil carbon sequestration in a Mediterranean almond orchard

The implementation of alley cropping in orchards can be a sustainable strategy to increase farm productivity by crop diversification and contribute to climate change mitigation. In this research, we evaluated the short-term effect of alley cropping with reduced tillage on soil CO2 and N2O emissions and soil total organic carbon (TOC) in an almond orchard under Mediterranean rainfed conditions. We compared an almond monoculture with tillage in all plot surface (MC) with almond crop with reduced tillage and growth of Capparis spinosa (D1) and almond crop with reduced tillage and growth of Thymus hyemalis (D2). For two years, soil CO2 and N2O were measured, with soil sampling at the start and end of the experimental period. Results showed that CO2 emission rates followed the soil temperature pattern, while N2O emissions were not correlated with temperature nor moisture. Soil CO2 emissions were significantly higher in MC (87 mg m−2 h−1), with no significant differences between D1 and D2 (69 mg m−2 h−1). Some peaks in CO2 effluxes were observed after tillage operations during warm days. Soil N2O emission rates were not significantly different among treatments. Cumulative CO2 and CO2 equivalent (CO2e) emissions were significantly highest in MC. When CO2e emissions were expressed on a crop production basis, D2 showed the significantly lowest values (5080 g kg−1) compared to D1 (50,419 g kg−1) and MC (87,836 g kg−1), owing to the high thyme yield, additional to the almond yield. No production was obtained for C. spinosa, since at least two more years are required. TOC did not change with time in MC neither D1, but it significantly increased in D2 from 3.85 g kg−1 in 2019 to 4.62 g kg−1 in 2021. Thus, alley cropping can contribute to increase the agroecosystem productivity and reduce CO2 emissions. However, it is necessary to grow evergreen alley crops such as thyme to obtain short-term increases in soil organic matter. Thus, to estimate increases in TOC with alley cropping, the plantation density and the period required by the crop to cover most of the surface are essential factors at planning the cropping strategy.

Performance of Multicut Fodder Sorghum Under Rainfed Conditions of Chamarajanagar District, Karnataka

ICAR-KVK, Chamarajanagar has conducted 170 (17 ha) demonstrations on multicut fodder sorghum during 2016-17, 2018-19, 2019-20 and 2020-21 in 8 villages. The critical inputs were identifi ed in existing production technology through farmers meeting and group discussions with the farmers. The study revealed that the demonstrated technology recorded signifi cantly a mean yield of 28.14 t/ha which was 133.14 % higher than farmers’ practice (12.07 t/ha). The palatability was also signifi cantly higher with CoFs-29 (92.8 %) as compared to local variety (80.5 %) and similar trend was followed with respect to number of cuttings. Average extension gap, technology gap and technology index were found 16.07 t/ha, 7.86 t/ha and 21.83% respectively. Higher mean gross and net returns and Benefi t: Cost ratio of Rs. 46435/ha, Rs.31489/ha and 3.11 was obtained with multicut fodder sorghum in comparison to farmers’ variety (Rs.19924/ha, Rs.7778/ha and 1.64). Therefore, there is a need to disseminate the improved technologies among the farmers with eff ective extension methods like training and demonstrations. The farmers should be encouraged to grow multicut fodder sorghum varieties under rainfed conditions to get higher green fodder yield and to realize higher returns.

Evaluation of Aus rice genotypes grown under rainfed and irrigated conditions

Bangladesh must keep increasing the production of rice (Oryza sativa L.), which is consumed by more than half of the world's population in order to ensure a steady supply of food for everyone. A field experiment was conducted to select short durated with high yield potential Aus rice genotypes under rainfed condition in a split plot design with three replications. Two water regimes (irrigated and rainfed) were imposed into main plot and 39 Aus rice genotypes were assigned into sub plots. In order to categorize the genotypes into various groups, multivariate studies including cluster analysis, principal component analysis (PCA), and discriminantfunction analysis (DFA) were carried out using fifteen quantitative plant traits. Results based on agronomic traits, the genotypes were grouped into six clusters. Early maturing genotypes are represented in cluster II, and genotypes with outstanding yield performance under irrigation are grouped in cluster III. Additionally, clusters III and IV indicate genotypes that mature quickly and a high yield potentiality under rainfed conditions, respectively. Biological yield played a very vital role under both irrigated and rainfed conditions. PCA revealed that PC 1, 2, 3, 4, and 5 described 84.90% variation under irrigated and 84.83% variation in rainfed condition, altogether. Stepwise DFA showed function 1 and 2 accounted for a cumulative of 95.40% of total variance in irrigated and of 92.3% variance in rainfed condition. BR24, Rupsail, Kachilon, Kachiloon2, Darial, Katak-Tara2, BRRI dhan43, Bowalia, BRRI dhan55 and BR14 showed the best performance under rainfed condition. The genotypes like Laksmilota, Loroi, Dhala Saita-3 and Kala manik can be used for further study as early maturing genotypes. Ann. Bangladesh Agric. (2022) 26 (1) : 91-111

Influence of Colchicine Concentrations on Wheat Seeds Germination and Seedling Quality

The study investigated the effect of colchicine (C) on seeds germination, as well as morph physiological traits of wheat, where dry wheat seeds were treated with colchicine at concentrations of (C) were (0.02, 0.04, 0.06, and 0.08 %) compared to soaking in distilled water (control). The variance analysis results of laboratory germination experiments as well as in field experiments under rain-fed conditions showed that there were significant differences (P < 0.05) in the mean of most of the studied quantitative traits: germination quality such as germination force (%), germination energy (%), and laboratory germination (%). Leaf area (cm2 ), root spread, stem diameter (cm), as well as wet and dry weight under the influence of the different concentrations of colchicine. Where the results showed that when used wheat seeds which pre-soaked with colchicine solution at a concentration of (0.06) % for 56 hours pre-sowing, led to an obvious significant increase in all studied traits morph physiological properties and seedling vigor when compared to the control (untreated seeds - treated with distilled water only) as well as when compared with other concentrations of colchicine.

Yield Response of Faba Bean to Lime, NPSB, and Rhizobium Inoculation in Kiremu District, Western Ethiopia

Faba bean (Vicia faba L.) is one of the most important winter legume crops for human consumption as a green or dried, fresh, or canned. Low soil fertility and acidity are the major constraints of faba bean production in Ethiopia. A field experiment was conducted in the Kiremu district of West Oromia, Ethiopia, under rain-fed conditions on a farmer's field to evaluate the effect of different rates of lime and NPSB-blended fertilizer application with and without inoculation on yield components and yield of faba bean. The three factors, lime rates (0, 2, and 4 t ha−1), mineral fertilizer rates (0, 60, 120, and 180 kg·ha−1 NPSB), and rhizobium inoculation (with and without), were combined in 3 x 4 x 2 factorial arrangement of RCBD in three replications. The data were collected on yield and yield components and subjected to the analysis of variance (ANOVA). The ANOVA results revealed that the number of pods per plant, number of seeds per pod, hundred seeds weight, harvest index, aboveground biomass, and grain yield were significantly affected by the treatment. Therefore, the highest faba bean yield was obtained from the application of 2 t limes ha−1, 120 NPSB ha−1, and 500 g·ha−1 rhizobium inoculation, and thus, the integrated application of the aforementioned rates of lime, NPSB, and rhizobium inoculation could be recommended for maximizing the productivity profitability of faba bean production in the study area and similar agro-ecologies.

Parsimonious root systems and better root distribution can improve biomass production and yield of soybean.

Enhancing the acquisition of belowground resources has been identified as an opportunity for improving soybean productivity worldwide. Root system architecture is gaining interest as a selection criterion in breeding programs for enhancing soil resource acquisition and developing climate-resilient varieties. Here we are presenting two novel characteristics of soybean root system architecture that improve aboveground growth and yield. Eleven selected soybean genotypes were tested under rain-fed conditions in 2019 and 2020 at two locations in South Carolina, in which one of the locations was characterized by compacted soils. The elite SC breeding line SC07-1518RR, exotic pedigree line N09-12854, and slow wilting line N09-13890 were superior genotypes in terms of biomass production, seed yield, and/or water use efficiency. Genotypes N09-12854 and N09-13890 demonstrated reduced root development (based on total root count and length), likely to restrict belowground growth and allocate more resources for shoot growth. This characteristic, which can be referred as a parsimonious root phenotype, might be advantageous for soybean improvement in high-input production systems (characterized by adequate fertilizer application and soil fertility) that exist in many parts of the world. Genotype SC07-1518RR exhibited a similar strategy: while it maintained its root system at an intermediate size through reduced levels of total root count and length, it selectively distributed more roots at deeper depths (53–70 cm). The increased root distribution of SC07-1518RR at deeper depths in compacted soil indicates its root penetrability and suitability for clayey soils with high penetration resistance. The beneficial root phenotypes identified in this study (parsimonious root development and selective root distribution in deeper depths) and the genotypes that possessed those phenotypes (SC07-1518RR, N09-12854, and N09-13890) will be useful for breeding programs in developing varieties for optimal, drought, and compacted-soil conditions.

A Comprehensive Review on Chickpea (Cicer arietinum L.) Breeding for Abiotic Stress Tolerance and Climate Change Resilience.

Chickpea is one of the most important pulse crops worldwide, being an excellent source of protein. It is grown under rain-fed conditions averaging yields of 1 t/ha, far from its potential of 6 t/ha under optimum conditions. The combined effects of heat, cold, drought, and salinity affect species productivity. In this regard, several physiological, biochemical, and molecular mechanisms are reviewed to confer tolerance to abiotic stress. A large collection of nearly 100,000 chickpea accessions is the basis of breeding programs, and important advances have been achieved through conventional breeding, such as germplasm introduction, gene/allele introgression, and mutagenesis. In parallel, advances in molecular biology and high-throughput sequencing have allowed the development of specific molecular markers for the genus Cicer, facilitating marker-assisted selection for yield components and abiotic tolerance. Further, transcriptomics, proteomics, and metabolomics have permitted the identification of specific genes, proteins, and metabolites associated with tolerance to abiotic stress of chickpea. Furthermore, some promising results have been obtained in studies with transgenic plants and with the use of gene editing to obtain drought-tolerant chickpea. Finally, we propose some future lines of research that may be useful to obtain chickpea genotypes tolerant to abiotic stress in a scenario of climate change.

Formulation of Abiotic Triggers for Prediction of Thrips and Whitefly Pest in Bt Cotton under Rainfed Condition of Maharashtra

Formulation of Abiotic Triggers for Prediction of Thrips and Whitefly Pest in Bt Cotton under Rainfed Condition of Maharashtra

Exploration of Alternative Approaches to Phenotyping of Late Leaf Spot and Groundnut Rosette Virus Disease for Groundnut Breeding

Late leaf spot (LLS), caused by Nothopassalora personata (Berk. & M.A Curt.), and groundnut rosette disease (GRD), [caused by groundnut rosette virus (GRV)], represent the most important biotic constraints to groundnut production in Uganda. Application of visual scores in selection for disease resistance presents a challenge especially when breeding experiments are large because it is resource-intensive, subjective, and error-prone. High-throughput phenotyping (HTP) can alleviate these constraints. The objective of this study is to determine if HTP derived indices can replace visual scores in a groundnut breeding program in Uganda. Fifty genotypes were planted under rain-fed conditions at two locations, Nakabango (GRD hotspot) and NaSARRI (LLS hotspot). Three handheld sensors (RGB camera, GreenSeeker, and Thermal camera) were used to collect HTP data on the dates visual scores were taken. Pearson correlation was made between the indices and visual scores, and logistic models for predicting visual scores were developed. Normalized difference vegetation index (NDVI) (r = –0.89) and red-green-blue (RGB) color space indices CSI (r = 0.76), v* (r = –0.80), and b* (r = –0.75) were highly correlated with LLS visual scores. NDVI (r = –0.72), v* (r = –0.71), b* (r = –0.64), and GA (r = –0.67) were best related to the GRD visual symptoms. Heritability estimates indicated NDVI, green area (GA), greener area (GGA), a*, and hue angle having the highest heritability (H2 > 0.75). Logistic models developed using these indices were 68% accurate for LLS and 45% accurate for GRD. The accuracy of the models improved to 91 and 84% when the nearest score method was used for LLS and GRD, respectively. Results presented in this study indicated that use of handheld remote sensing tools can improve screening for GRD and LLS resistance, and the best associated indices can be used for indirect selection for resistance and improve genetic gain in groundnut breeding.

EVALUATION OF RELEASED TEF (ERAGROSTIS TEF [ZUCC.] TROTTER) VARIETIES AT SOUTHWESTERN PART OF ETHIOPIA

Objective: The objective of the study was to evaluate performance and identify high yielding and stable variety for southwestern part Ethiopia and recommend identified varieties for large scale production. Experimental Materials: Eight nationally released tef varieties were included in the study. The materials were obtained from Debre Zeit Agricultural Research Center (DZARC). Design and Trial Management: The experiment was conducted during the 2019 main cropping season at six locations, namely: Melko, Gechi, Omonada, Kersa, Mana, and Gooma weredas of Southwestern Ethiopia. The trial was conducted using randomized complete block design with three replications at all locations under rain-fed conditions. Sowing was done manually. Spacing between plots was 1 m, whereas that between replications was 1.5 m and the total plot size was 2 m × 2 m. Seed rates were based on the recommendation which was 15 kg/ha. Result and Discussion: Analysis of variance revealed the presence of significant (P < 0.05) differences among eight tef varieties of traits of days to heading, days to maturity, plant height, panicle length, lodging index, above ground biomass, and grain yield across locations. This indicated the presence of performance variation among the tested varieties for grain yield and it is possible to identify high yielder varieties for possible use in these locations. Conclusion and Recommendation: In general, varieties Dagim and Kora were high yielding and stable across locations and variety Gibe, Tesfa, and Negus were stable and low yielders across locations. The high yielding and stable varieties were recommendable for large scale production in southwestern part of Ethiopia. The experiment used data collected for only one season, which may limit the strength of its recommendation. However, the results are crucial in directing the breeding decision following additional season evaluation of the varieties in the same locations.

On-farm hydro and nutri-priming increases yield of rainfed pearl millet through physio-biochemical adjustments and anti-oxidative defense mechanism.

Seed priming technique has a marvelous potential in enhancing seed germination and crop establishment under limited soil moisture conditions, which ultimately increases yield. Therefore, we investigated the effects of seed priming on physiology, growth, yield and antioxidant defense system of pearl millet (Pennisetum glaucum L.) under rain-fed condition. The experiments were conducted under laboratory as well as field conditions comprising three treatments i.e., non-primed seeds (control, T0), priming with tap water (hydropriming) (T1) and priming with 2% KNO3 2% for 6 hours at 25°C followed by shade drying (T2). The results showed that chlorophyll content (10.37-14.15%) and relative water content (RWC) (12.70-13.01%) increased whereas proline (-19.44 to -25%) and soluble sugar (-15.51 to -29.13%) contents decreased on account of seed priming in pearl millet under field conditions. The seed priming significantly improved the plant height, final plant stand and grain weight which resulted in increased yield. Enhanced activities of superoxide dismutase (SOD) (5.89 to 8.10 unit/g/seed/min), catalase (CAT) (22.54 to 39.67 µmol/min/g/seed) and ascorbate peroxidase (APX) (8.92 to 22.10 µmol/cm/min/g) and concomitant decrease in H2O2 and malondialdehyde (MDA) content suggests their role in imparting oxidative tolerance at initial stages of growth in primed seed. The lab studies suggest that the improved yield might be attributes to increased seed germination and seedling vigor. It is recommended that the hydropriming (tap water) or KNO3 (2%) priming of seeds for 6 hours under ambient conditions is effective to enhance growth and yield of pearl millet under rainfed conditions.

Determination of Forage Quality Properties of Plant Parts in Different Amaranth Varieties Cultivated Under Irrigated and Rainfed Conditions

Determination of Forage Quality Properties of Plant Parts in Different Amaranth Varieties Cultivated Under Irrigated and Rainfed Conditions

GENETIC DIVERSITY STUDIES, HERITABILITY, CORRELATION AND PROXIMATE ANALYSIS AMONG ACHA (Digitaria exilis) ACCESSIONS

The study assessed variability, heritability and genetic relationships in the proximate composition among 14 Acha (Digitaria exilis Staph) accessions collected from Tafawa Balewa and Bogoro Local Government Areas of Bauchi State in North Eastern Nigeria. Entries were pretested in the screen house in plastic pots in 2017 and later evaluated in the field under rain-fed conditions in 2017 and 2018 using a randomized complete block design with three replications. Three (3) samples of harvested grain, for each entry, were subjected to proximate analysis in the laboratory to determine their percent proximate composition in: Crude protein (% CP), Crude fiber (% CF), Ether extract (% EE), Ash content (% Ash) and Nitrogen free extract (%NFE) using standard Analytical methods. Analysis of variance was done using Genstat version 16th). Results obtained in this study revealed that all biochemical parameters differed significantly (P≤0.001) among these accessions. Mean percent in crude protein (CP) was 7.5 %, Crude Fiber was 0.85 %, while that of ether extract (%EE) and ash content (% Ash) were 1.94% and 1.87%, respectively. Except for Ether Extract, other biochemical variables under investigation recorded negative correlation with grain yield. Phylogenetic studies revealed two cluster groups among acha accessions. High percent heritability values, in broad sense of (between 77% and 99 %), couple with high genetic advance as percent of mean (GAM) were recorded for most of characters under investigation, indicating a good scope for improvement through selection.

Weather parameters largely regulate the outbreak of rice bacterial blight: an endemic disease poses a threat for food security in Bangladesh

Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae is a destructive disease of rice causing significant yield losses. Surveys were conducted to know the influence of weather parameters on epidemic development of BB in the thirty agroecological zones of Bangladesh. The maximum (55.11%) bacterial blight incidence and severity were recorded Mymensingh division (AEZs 8 and 9) while the minimum (3.25%) incidence was observed in Barishal division (AEZ 13) in both rainfed and irrigated seasons. In rainfed conditions, the maximum BB incidence and severity were recorded in hybrid varieties Aloron from Netrokona (AEZ 9) and the minimum incidence was observed in the local variety Sughondi from Jalhokhati (AEZ 13). On the other hand, in irrigated conditions, the highest BB incidence was recorded in the hybrid variety Hera-2 from Netrokona (AEZ 9) and the lowest incidence was observed in the local variety from Hobiganj (AEZ 20, 21, 22). Swarna, Puja, BRRIdhan28, BRRIdhan29, and BRRIdhan49 showed intermediate levels of infection, while hybrid Hera-2, Arize TejGold, Partex, Agrodhan, Aloron, ACI-2, and Dhani Gold showed higher level of infection (susceptibility) to BB. The data analysis on BB incidence with the weather parameters of rice growing seasons from 2015 to 2017 revealed that the rainfall distribution varied greatly within rice growing seasons over the years. The results indicated that weather parameters, viz. temperature (25-34°C), relative humidity (70-84%), and rainfall (>200mm), largely affected the prevalence, incidence and severity of BB. The correlation studies revealed that, among the climate variables, minimum temperature exhibits a negative correlation. However, rainfall, maximum temperature, morning relative humidity and evening relative humidity were found positively correlated, while wind velocity imparted a significant positive correlation with BB infection. The regional outbreak of BB indicated a considerable yield loss of rice and give rise a threat for food security of the country.

Assessing the genetic diversity for yield traits in rice (Oryza sativa L.) genotypes using multivariate analysis under controlled and water stress conditions

The genetic diversity of yield and yield attributing characteristics was explored in this research. In the topical study, fifty-two rice genotypes including four checks were used under three environmental conditions i.e. irrigated (IR), rainfed (RF) and terminal stage drought (TSD) conditions. The prevalence of genetic divergence was evaluated using clustering and Principal component analysis (PCA) was used to determine the relative contribution of various traits. To fulfill the aim of the study, fifty-two genotypes were grouped into three distinct and non-overlapping clusters among these 3 clusters, cluster-I was the largest with the highest number of genotypes i.e. 47, 49 and 49 under IR, RF and TSD conditions, respectively. The highest average intra-cluster distance was observed in cluster-I, also the genotypes showed high variability under all three conditions. The highest inter-cluster distance between the cluster-II and cluster-III (IR and TSD) and cluster-I and cluster-II (RF) was observed, indicated that genotypes from the group should be considered for direct use as parents in hybridization programme to produce high yield. Only five of the 13 principal components (PCs) have been considered in the study based on the Eigen values and variability criteria. From the complex matrix it was revealed that the first-PC accounted for the highest variability. Genotypes which fall under a common PC were observed to be the most important factor for grain yield.