Lowest Yield Reduction Research Articles

Maize yield, biomass and grain quality traits responses to delayed sowing date and genotypes in rain-fed condition

Delayed sowing (DS) is a critical factor influencing grain yield and quality under climate change. This study was conducted to determine maize grain yield and quality traits responses to DS and varied genotypes in rain-fed condition, northeast of China. Two typical hybrids ZD958 (higher starch type) and LM33 (higher protein type) and three sowing dates: 30 April (DS0) as normal, 10 May (DS10) and 20 May (DS20) were compared. Results demonstrated maize grain yield, biomass, kernel number per square, thousand kernel weight (TKW), grain nutrition yield, N concentration and grain test weight were significantly reduced by DS. Compared to high protein type LM33, high starch type ZD958 had a higher yield potential and lower yield reduction with delayed sowing. Grain yield loss under DS could be mainly attributed to reduction of the BMP and biomass, thereby leading to the reduction of TKW and kernels number per unit. DS didn’t affected grain nutritional content (starch, protein and oil), while significantly reduced grain nutrition yield of starch, oil and protein with delayed sowing. This study suggests that, early sowing should be recommended to the framers and varieties adjustments maybe a possible approach to reduce and compensate for the loss of yield caused by delayed sowing in rain-fed condition under climate change in NCP.

Heat stress tolerance study in eggplant based on morphological and yield traits

High temperature has detrimental effects on growth and yield of any crops. A total of 62 two eggplant genotypes were evaluated for growth and yield traits at two growing season during summer season (March-July) and kharif season (July-November). Average of three replications was used for each trait in statistical analysis involving one way analysis of variance (ANOVA), Principal Component Analysis (PCA) and Agglomerative Hierarchial Clustering (AHC) using SAS ver. 9.3 and R package. Analysis of variance indicated high variability for all the traits among the eggplant genotypes. Highest yield per plant was recorded in Guhala Chatua Local (1.8 kg) in summer season whereas in kharif season, yield per plant was maximum in Swarnamani Black (5.97 Kg). The mean yield per plant (1.83 kg) was more in kharif season as compared to summer season (0.09 kg). The percentage yield reduction in summer season was more than 90% in almost all the genotypes and the lowest yield reduction (22.11%) was found in Guhala Chatua Local followed by DBL-21 and DBL-08. In summer season, the first principal component (PC1) and second principal component (PC2) could explain 48% and 14% of total variance, respectively where yield per plant contributed positively to PC1. In kharif season, first principal component (PC1) and second principal component (PC2) could explain 33% and 20% of the variance, respectively where total number of fruit weight per plant, fruit diameter and yield per plant traits contributed positively to PC1. The Hierarchical cluster analysis revealed five clusters based on the similarities among the genotypes in both summer and kharif season but the clustering pattern was different among season. Based on the study, promising heat-tolerant genotypes (Guhala Chatua Local, DBL-21 and DBL-08) have been identified which could be novel source for heat tolerance gene (s) for utilizing in breeding programme.

Physiological traits determining tolerance to intermittent drought in the Capsicum annuum complex

The use of physiological traits directly-linked to mechanisms of drought tolerance (DT) as selection criteria could accelerate the development of tolerant varieties. To identify such physiological traits in chilli pepper (Capsicum annuum L.), we screened a range of diverse genotypes, a series of parental breeding lines produced from C. annuum and C. frutescens/C. chinense crosses, under well-watered and water-stressed (65% depletion of available soil water) conditions in the field with a movable rainshelter. Water regime x genotype interaction was significant (p < 0.05) in the majority of measured traits, which showed significant genotypic variation under the two water regimes. Stomatal conductance (gs) showed strong positive correlations with yield under both water regimes. Furthermore, relative reduction of gs in response to drought positively correlated with relative yield reduction. Canopy temperature (Tc) showed significant negative correlations with yield in both water regimes. Lower yield reductions due to drought were associated with lower increases of Tc across the genotypes. Similarly, lower reductions in shoot relative water content were strongly correlated to lower yield reductions. Yield under drought (Yd) showed significant positive correlation to maximum rooting depth and dry root weight. Greater flower numbers and conversion of flowers to pods, traits indicating the DT of reproductive processes positively correlated with Yd. Factor Analysis showed that the above physiological, growth and reproductive traits constituted composite traits which underpin DT in chilli. As such, they can be used as screening tools in identifying drought tolerant germplasm in breeding programmes of Capsicum annuum.

Effect of Irrigation Method on Adaptation Capacity of Rice to Climate Change in Subtropical India

Water management technologies under projected climate change will play key role in sustainable rice production. Modeling approach was used to assess the impact of climate change on rice production under drip irrigation (DIR) and conventional puddle transplanted (PTR) in subtropical India. The genotype coefficients of CERES-Rice model (cv. Naveen) were determined and tested using experimental data for the years 2012–2014. Close match between the observed and simulated values was recorded during both the years which led to higher d-index (> 0.95) and lower normalized RMSE (RMSEn) values. Under the projected climate change scenarios (RCP 4.5 and RCP 8.5), grain yield reduced over the period 2020–2080, with higher decline in RCP 8.5. Over the period, higher nitrogen (N) use efficiency in DIR led to lower yield reduction over PTR. Among the different adaptation measures, higher fertilizer N dose was able to mitigate negative impact of temperature rise up to 3.3 °C over base period, beyond which grain yield was significantly reduced. Results of the simulations for the different sowing dates stated higher reduction in grain yield with delayed sowing in DIR as well as in PTR for both (RCP 4.5 and 8.5) climate change scenarios. However, early sowing resulted in better crop establishment in DIR leading to better yield compared to PTR in both the climate change scenarios.

Identification of genome-wide single-nucleotide polymorphisms (SNPs) associated with tolerance to chromium toxicity in spring wheat (Triticum aestivum L.)

Chromium (Cr) toxicity is a rapidly increasing environmental concern and poses a major threat to plant growth as well as food chain. This study was carried out to screen spring wheat diversity panel against Cr toxicity to assess yield reduction, grain contamination extents and genomic regions associated with tolerance to Cr toxicity. The diversity panel was planted in control and Cr stress (26 mg Cr/kg soil) in paved plots, and several morphological and physiological traits were recorded. Wheat 90 K Infinium iSelect SNP array was used to identify genomic regions underpinning tolerance to Cr toxicity. Some wheat cultivars (Khosar-95, Miraj-08, Millet-11, Sarsabaz and NARC-11) had Cr concentration within international edible threshold limit (1 ppm), but showed greater reduction to grain yield (63–95%) due to higher leaf Cr concentrations (2.35–8.95 ppm). Contrastingly, wheat cultivars Auqab-00 and Pakistan-13 had lower yield reduction up to 9% and 39%, respectively but had higher concentration of Cr in seeds (2.1 and 3.5 ppm, respectively). Genome-wide association studies identified 71 loci linked with yield related traits under Cr stress and 48 loci for differences between control and Cr stress treatments. Further, gene ontology of trait-associated SNPs revealed proteins with significant importance in plant development and tolerance against heavy metal stress. To our knowledge, this is the first study for identification of genomic regions linked to Cr stress, suggesting that this could be useful to identify complex architecture of genetic factors as well as molecular breeding opportunities for tolerance to Cr stress.

Genetic diversity and phenotypic variation for drought resistance in alfalfa (Medicago sativa L.) germplasm collected for drought tolerance

Drought is a major environmental factor hampering alfalfa productivity worldwide. Gene banks provide an array of trait diversity, frequently consisting of specific seed collection projects that focused on acquiring germplasm adapted to specific traits such as drought tolerance. These subsets provide a logical starting point to identify useful breeding resources. In the present study, we investigated the genetic diversity and evaluated 18 agronomic, physiological and quality traits associated with drought tolerance in a subset of 198 alfalfa accessions collected for their potential drought resistance. Significant differences were found among accessions for most of the traits evaluated. Water deficit significantly decreased biomass dry yield by 61.9% compared with well-watered control. A positive correlation was found between relative water content (RWC) and drought susceptible index, while negative correlations were found between RWC and leaf senescence (LS), and between RWC and canopy temperature (CT). Alfalfa accessions with high RWC showed relative lower yield reduction, cooler CT and delayed LS. Genetic variation for forage quality was also investigated and the correlation between agronomic and quality traits was analyzed. Biomass yield under drought was negatively correlated with total protein, relative feed value and relative forage quality, suggesting that the efforts to improve yield under drought tend to negatively affect forage quality. Therefore, maintaining forage quality should be considered for breeding alfalfa with drought resistance. Alfalfa accessions with high drought resistance scores and minimum loss of quality were identified in this study and can be used as genetic resources for developing alfalfa varieties with improved drought resistance and water use efficiency while maintaining forage quality.

Selection of drought-tolerant tef (Eragrostis tef) genotypes using drought tolerance indices

Drought stress is one of the major abiotic constraints affecting production and productivity of tef (Eragrostis tef). Genetic resources and selection methodologies are among the prerequisites to improve the efficiency of breeding for drought tolerance. The objectives of this study were to determine the principal selection indices and to identify promising genetic resources of tef for drought tolerance breeding. A total of 144 tef genotypes were evaluated using a simple lattice design with two replications. Genotypes showed highly significant (p ≤ 0.01) differences for 10 drought tolerance indices. Principal component and correlation analyses revealed mean productivity, harmonic mean, geometric mean productivity and stress tolerance index as the principal indices highly correlated with grain yield in the stressed and non-stressed environments, indicating their suitability for identifying superior tef genotypes. Genotypes 215678 (g25) and Dschanger (g133) were adaptable to both stressed and non-stressed environments, which could be useful for drought stress tolerance breeding. Genotypes DZ-Cr-387 (g1), 9403 (g4), 205896 (g48) and 9415 (g122) were selected for their higher grain yield under the non-stressed condition. Genotypes DZ-Cr-385 (g22) and DZ-Cr-37 (g28) were selected for their lower yield reduction under moisture stress, intermediate grain yield performance in the non-stressed environment and high grain yield potential in the moisture-stressed environment.

Impact assessment of climate change on groundnut yield of middle Gujarat region

The impact of projected climate change on groundnut (cv. Robut 33-1 and GG-2) yield have been studied for Anand station of middle Gujarat Agro-climatic region using PRECIS output of A2 scenario and base line data. Yield simulation study was performed by PNUTGRO (DSSAT v4.5) model. The field experiment data on groundnut cv. Robut 33-1 and GG-2 during the years 2008 to 2011 have been used to calibrate and validate the model. The weather condition as projected by A2 scenario (2070-2100) showed that there will be 13.7% higher rainfall as compared to base line (1961-90). The mean maximum and minimum temperature will be higher to the tune of 3.6 and 5.1 °C as compared to their base temperature of 19.1 and 29.8 °C respectively. Nearly 21 and 31% pod yield reduction was noted in Robut 33-1 and GG-2 as compared to their base yield during projected period. Highest yield reduction was recorded in late sowing (15th July) and cv. GG-2 and lowest yield reduction was noted in timely sowing (D1) and cv. Robut 33-1. Under projected period. 7.0 to 16.0% yield benefited by adaptation strategies, viz, fifteen days earlier shifting of sowing with one pre sowing irrigation and Application of organic manure instead of chemical fertilizer.

Physiologic and agronomic traits in safflower under various irrigation strategies, planting methods and nitrogen fertilization

Drought and limited supplies of water in many areas of the world have created serious concerns about agricultural production and global food security. Hence, application of more efficient management strategies in fields has been favourably developed in arid and semi-arid regions. In this respect, physiological and agronomic behaviour of a crop can be an advantageous index for identification of its response to different management policies. The objective of this study is to investigate the effects of partial root drying (PRD) irrigation, planting methods and nitrogen fertilization on some agronomic and physiologic behaviour of safflower (Carthamus tinctorius L.). The experiment was designed as split–split plot that arranged in randomized complete blocks with irrigation strategy as the main plot, planting method as the subplot and nitrogen levels as the sub-subplot in three replications. The irrigation strategies consisted of ordinary furrow irrigation (OFI) and variable alternate furrow irrigation (VAFI) as a PRD technique. The planting methods included of on-ridge planting (P1) and in-furrow planting (P2) methods The fertilizer levels were 0 (N0), 100 (N1) and 200 (N2)kgha−1 of urea as 0, 46 and 92kgha−1 of nitrogen. Results of this study indicated that VAFI strategy can be an alternative irrigation policy for safflower farms in which certain irrigation water saving, low yield reduction and more drought adaptation in crop is provided. Furthermore, it was shown that safflower is relatively drought-tolerant to water stress in which the stem elongation stage was more sensitive to drought than the heading and flowering stages. Since, photosynthesis rate (An) was strongly correlated with heads formation (number of heads per plant, NHP) and seeds accumulation (number of seeds per plant, NSH) in safflower, the photosynthesis deficiency by water stress resulted in decrease of safflower seed yield mainly thorough the reduction in NHP and NSH than other components such as number of branch per plant (NBP) and thousand seeds weight (TSW). Based on findings, in-furrow planting method can be another favourable strategy due to its influence on enhancement of yields, photosynthesis, stomatal conductance (gs), transpiration rate (Tr), leaf area index (LAI) and vegetative growth of safflower. Besides, nitrogen fertilization at rate of 46kgha−1 is recommended for improving the agronomic and physiologic traits of safflower.

Physiological Basis of Water Stress Tolerance in Soybean

An experiment was conducted to study the effects of water stress on physiological parameters associated to drought tolerance in soybean at the Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh during January to April, 2015. Four soybean genotypes namely i) BU Soybean 1 ii) Binasoybean 1 iii) Galarsum and iv) BARI Soybean 5 were grown in two watering regimes viz. control (80% of the field capacity) and water stress (50% of the field capacity). Genotypic variability was found in water stress tolerance in soybean. Highest accumulation of leaf proline, sugar and water content and lower accumulation of malondialdehyde were found in Binasoybean 1 compared to other genotypes. Lowest yield reduction was found in Binasoybean 1. Binasoybean 1 showed relatively higher drought tolerance whereas BARI Soybean 5 was found susceptible to yield. It was found that higher water stress tolerance in Binasoybean 1 was associated with better water relations and higher accumulation of sugar and proline and lower accumulation of malondialdehyde content in leaf.Bangladesh Agron. J. 2015, 18(2): 71-78

Global Synthesis of Drought Effects on Maize and Wheat Production.

Drought has been a major cause of agricultural disaster, yet how it affects the vulnerability of maize and wheat production in combination with several co-varying factors (i.e., phenological phases, agro-climatic regions, soil texture) remains unclear. Using a data synthesis approach, this study aims to better characterize the effects of those co-varying factors with drought and to provide critical information on minimizing yield loss. We collected data from peer-reviewed publications between 1980 and 2015 which examined maize and wheat yield responses to drought using field experiments. We performed unweighted analysis using the log response ratio to calculate the bootstrapped confidence limits of yield responses and calculated drought sensitivities with regards to those co-varying factors. Our results showed that yield reduction varied with species, with wheat having lower yield reduction (20.6%) compared to maize (39.3%) at approximately 40% water reduction. Maize was also more sensitive to drought than wheat, particularly during reproductive phase and equally sensitive in the dryland and non-dryland regions. While no yield difference was observed among regions or different soil texture, wheat cultivation in the dryland was more prone to yield loss than in the non-dryland region. Informed by these results, we discuss potential causes and possible approaches that may minimize drought impacts.

Improved tolerance to post-anthesis drought stress by pre-drought priming at vegetative stages in drought-tolerant and -sensitive wheat cultivars

Wheat crop endures a considerable penalty of yield reduction to escape the drought events during post-anthesis period. Drought priming under a pre-drought stress can enhance the crop potential to tolerate the subsequent drought stress by triggering a faster and stronger defense mechanism. Towards these understandings, a set of controlled moderate drought stress at 55–60% field capacity (FC) was developed to prime the plants of two wheat cultivars namely Luhan-7 (drought tolerant) and Yangmai-16 (drought sensitive) during tillering (Feekes 2 stage) and jointing (Feekes 6 stage), respectively. The comparative response of primed and non-primed plants, cultivars and priming stages was evaluated by applying a subsequent severe drought stress at 7 days after anthesis. The results showed that primed plants of both cultivars showed higher potential to tolerate the post-anthesis drought stress through improved leaf water potential, more chlorophyll, and ribulose-1, 5-bisphosphate carboxylase/oxygenase contents, enhanced photosynthesis, better photoprotection and efficient enzymatic antioxidant system leading to less yield reductions. The primed plants of Luhan-7 showed higher capability to adapt the drought stress events than Yangmai-16. The positive effects of drought priming to sustain higher grain yield were pronounced in plants primed at tillering than those primed at jointing. In consequence, upregulated functioning of photosynthetic apparatus and efficient enzymatic antioxidant activities in primed plants indicated their superior potential to alleviate a subsequently occurring drought stress, which contributed to lower yield reductions than non-primed plants. However, genotypic and priming stages differences in response to drought stress also contributed to affect the capability of primed plants to tolerate the post-anthesis drought stress conditions in wheat.

Analysis of tolerance indices for germplasm evaluation in safflower (Carthamus tinctorius L.) subjected to terminal drought stress

In order to evaluate quantitative drought resistance criteria in some safflower genotypes, fiftheen genotypes were evaluated both under moisture stress and non-stress field environments using a randomized complete block design for each environment. The genotypes showed significant differences in grain yield and other traits. Grain yield under irrigated conditions was adversely correlated with water deficit condition, suggesting that high potential yield under optimal conditions does not necessarily result in improved yield under stress conditions. Genotypes G64, G92 and PI253527 showed lower yield reduction than the average of other genotypes. Surprisingly, most of the genotypes showed more than 30% yield reduction under drought stress. The positive correlation between TOL and irrigated yield (Yp) and the negative correlation between TOL and yield under stress (Ys) suggest that selection based on TOL will result in reduced yield under well-watered conditions. We conclude that GMP and STI are able to discriminate tolerant group of genotypes under both environments. Therefore, genotypes G47, G64, G42 and S411 are superior genotypes for both environments. Genotypes S310 , S149 and Almaneriz are more suitable for non-moisture stress than moisture-stress environment.

Response of Soybean Genotypes Challenged by a Stink Bug Complex (Hemiptera: Pentatomidae).

Pentatomids (stink bugs) are major pests of soybean, Glycine max (L.) Merril. These pests reach high levels of infestation, cause severe damage to seeds by feeding, are linked to leaf retention, and are difficult to control. Host plant resistance is considered to be a valuable tool in integrated pest management and can assist in reducing the damage caused by stink bugs. This research evaluated the resistance of soybean genotypes in Brazil to the stink bug complex, the Neotropical brown stink bug, Euschistus heros (F.), redbanded stink bug, Piezodorus guildinii (Westwood), southern green stink bug, Nezara viridula (L.), green belly stink bug, Dichelops melacanthus (Dallas), and Edessa meditabunda (F.), by assessing infestation assay, yield reduction, seed damage, and leaf retention. Certain genotypes expressed different categories of resistance: least infested, low yield reduction, low levels of damage in seeds, and low levels of leaf retention. PI lines and IAC 78-2318 showed antixenotic resistance, and ‘IAC 100’ showed tolerance for the stink bug complex. This is the first study to evaluate several parameters of yield and seed quality using different soybean maturity groups under relatively high infestation by the three stink bugs species. The promising genotypes might be used in regions with a high incidence of stink bugs to manage their populations in combination with other integrated pest management practices.

Canopy Temperature and Yield Based Selection of Wheat Genotypes for Water Deficit Environment

The experiment was conducted with thirty-five wheat genotypes at the research field of the Department of Agronomy of the Bangabandhu Sheikh Mujibur Rahman Agricultural University from November 2011 to March 2012 to screen out the wheat genotypes for drought tolerance of thirty-five wheat genotypes under water deficit condition. The experiment was carried out in a split-plot design comprising two water regimes in main plot and thirty-five wheat genotypes were placed randomly in sub-plot with three replications. From this experiment, it was found that water deficit condition severely reduced the plant height, number of effective tillers m﹣2, spike length, number of spikelets spike﹣1, number of grains spike﹣1 and thousand grain weight. Based on the percentage of yield reduction, the genotypes BARI Wheat 26, Sourav, BAW 1169 and BAW 1158 were categorized in tolerant group exhibited low yield reduction (>30%) and the genotypes Seri, Pavon, BAW 1166, BAW 1167, BAW 1171 and BAW 1173 were ranked in susceptible group due to very low yielding ability with high yield reduction which ranged from 50.01% to 59.17% in water deficit condition. The maximum increased canopy temperature was recorded in the genotypes BAW 1166, BAW 1167, Seri, Pavon and BARI Wheat 25. The minimum was in the genotypes BARI Wheat 26, BAW 1157, Sourav, BAW 1169 and Gourab. The highest MP, GMP and STI values were recorded in the genotypes BARI Wheat 26, BAW 1158, Sourav, BAW 1169 and BAW 1170. Our results revealed that BARI Wheat 26, BAW 1158, Sourav, BAW 1169 and BAW 1170 were more capable to tolerate water deficit condition.

Performance of Maize Single-Cross Hybrids Evaluated on Acidic Soils

Soil acidity is one of a number of limiting factor of maize production. Planting maize hybrid varieties tolerant to acid soils along with the use of sustainable agronomic practices offers an effective solution for improving maize productivity on acidic soils. Thirty-six single-cross hybrids derived from a 9x9 diallel cross, nine parental inbred lines and two check varieties i.e. a commercial hybrid and a composite variety Sukmaraga were evaluated in 2013 on acid aluminum-toxic soil at Limau Manis Padang in a randomized compelete block design in order to evaluate and select maize hybrids for high yield potential in acid soils and tolerant to acid soils. Data were subjected to the analysis of variance using the Proc GLM of the SAS software, while analysis of diallel was conducted using DIALLEL-SAS05 software. Results showed that several hybrids which were progenies of crossess between acid soil-tolerant or moderately acid soil-tolerant inbred lines revealed high grain yield on acidic soils. The hybrids also revealed high heterosis magnitudes and high and positive specific combining abilities, low yield reduction and stress sensitivity indices, while they revealed high relative yield and stress tolerance indices. Hence, it is suggested that these promising hybrids can be further evaluated in large scale locational trials on acidic soils.

Influence of Fertilization System on Wheat Yields in Terms of Global Climate Change

Over the last few decades, wheat production, both in Serbia and worldwide, has been practiced under characteristic agrometeorological conditions. It has generally been affected by specific strongly marked agrometeorological and climate extremes, most notably extreme temperature and drought events during critical periods in the growing season, which mostly had a negative impact on the growth, development and yield of wheat in Central Serbia.This paper presents results and discussion on both the potential effect of climate change on winter wheat yield and the possibility to alleviate it through an appropriately adjusted fertilization system.The present study on the effect of different rates and ratios of NPK fertilizers on grain yield in seven winter wheat cultivars under different (dry and “normal“) conditions during the year was conducted in a long-term field experiment at the Small Grains Research Centre in Kragujevac over a period of seven years (2000/01-2006/07).Depending on the fertilization treatment, the average yield reduction in dry years showed 50% variation relative to “normal” years. The highest reduction in grain yield and other productive traits of wheat in dry years was observed in the treatment involving nitrogen nutrition, particularly lower application rates. As compared to the non-treated control, the use of complete NPK fertilization having an increased amount of phosphorus resulted in the lowest yield reduction during the dry years that were unfavorable for winter wheat production. The average grain yield reduction in dry years was lowest in wheat cultivar Matica and highest in Kg-100, respectively.

Evaluation of growth, yield, relative performance and heat susceptibility of eight wheat (Triticum aestivum L.) genotypes grown under heat stress

Eight spring wheat cultivars were evaluated under three heat stress conditions (early, late and very late) in order to identify suitable cultivars to develop heattolerant genotypes resistant to future global warming. Results from the study indicate that stress did not negatively affect flag leaf area in ‘Prodip’ and ‘Sufi’, flag leaf dry matter partitioning in ‘Prodip’, ‘BARI Gom-26’ and ‘Shatabdi’, above-ground dry matter partitioning in ‘Shatabdi’ and ‘BARI Gom-26’, seedling emergence in ‘Sufi’ and ‘BARI Gom-26’, or tiller production in ‘Sufi’ and ‘BARI Gom-26’. With respect to lower yield reduction, relative performance and heat susceptibility index (HSI), ‘Sufi’ was highly heat stress-tolerant, followed by ‘BARI Gom-26’ and ‘Shatabdi’. On the basis of HSI values in early heat stress and extremely late heat stress (corresponding to early and extremely late sowing), ‘BARI Gom-26’ (HSI=0.10, 0.65) and ‘Shatabdi’ (0.22, 0.62) were highly tolerant to early heat stress and moderately tolerant to extremely late heat stress while ‘Sufi’ was highly tolerant (0.35) to extremely late heat stress and moderately tolerant (0.51) to early heat stress. All other genotypes were susceptible to heat stress, among which ‘Gourab’ (2.19, 1.46) was the most susceptible followed by ‘Sourav’ (1.19, 1.42), ‘Prodip’ (1.03, 1.23), ‘BARI Gom-25’ (1.61, 0.89) and ‘Bijoy’ (1.04, 1.28). Thus, ‘BARI Gom-26’, ‘Shatabdi’ and ‘Sufi’ have the greatest potential to be used as high-yielding wheat genotypes under warm to hot environments and could be used in a breeding programme to develop heat-tolerant wheat.

Evaluation of Some Botanicals and Entomopathogenic Fungi for the Control of Onion Thrips (Thrips tabaci L.) in West Showa, Ethiopia

Onion thrips (Thrips tabaci L.) is one of the most important serious insect pests of onion (Allium cepa L.) cultivation in Ethiopia. The present study was conducted to evaluate some botanical extracts viz. Artemisia annua, Azadirachta indica, Bidens pilosa, Chrysanthemum cinerariaefolium, Cymbopogon citratus, Nicotiana tabacum, Nicotiana spp.,(local var.,), Parthenium hysterophorous, Phytolacca dodecandra, Securidaca longepedunculata and two indigenous isolates of entomopathogenic fungi (EPF) viz. Beauveria bassiana (PPRC-56) and Metarhizium anisopliae (PPRC-6) and soap detergent powder. They were examined for controlling onion thrips (Thrips tabaci L.) under field condition in Guder, Toke Kutaye district of Ethiopia from mid October 2010 to early April 2011. Diazinon 60% E.C was applied at the recommended rate of 1.8 l/h and the plot left was examined as controls. After 1st day application of the different agents, EPF and untreated control were not significantly different. However, the results on 3rd, 5th, and 7th day after application of EPF treatments indicated that highly significant mortality. The rate of mortality in all of the treatments after 1st day ranged from 0 to 74.75%. On the other hand, botanical extracts recorded at 3rd day of application ranged from 26.09 to 74.75% within 3days of the higher mortality was recorded. On 5th and 7th day, except B. bassiana (PPRC-56), the mortality rate in all treatments became declined. The results indicated that insecticidal actions of all the tested agents exhibited to the ranging from 26.09 to 74.75% against onion thrips. Of the different agents, Nicotiana spp., P. dodecandra, S. longepedunculata and N. tabacum exhibited high mortality rate (69.65, 68.99, 63.85 and 63.56%, respectively), whereas in C. cinerariaefolium, A. indica and P. hysterophorous showed intermediate mortality rate (60.79, 56.89 and 52.06 respectively) and the rest were the lowest mortality rate. High bulb yield reduction was recorded in untreated plots but low yield reduction was observed in treated plots and control check. The treatments also showed reducing onion thrips population and also gave significant control over the treated check. This study indicated that Nicotiana spp., P. dodecandra, S. longepedunculata, N. tabacum and B. bassiana were significantly very effective against onion thrips under field condition at recommended rate and then confirmed the valuable rate of botanicals and EPF as components of Integrated Pest Management (IPM) practices in Ethiopia.

Epidemiological aspects of bean decline disease caused by Fusarium species and evaluation of the bean resistant cultivars to disease in Northwest Iran

The national project of Iran aimed to study the etiology of bean decline disease and the induction of bean resistant cultivars to the disease. Samples of 75 infected bean plants (300 in total) were collected from four growing locations in three provinces of Northwest Iran. The isolated pathogens were Fusarium solani (41.6%), Fusarium oxysporum (32%), Fusarium sambucinum Fuckel (18%), Rhizoctinia solani (5.4%) and Pythium debaryanum (2.7%). Sufficient inoculums of three Fusarium species were prepared in chaff medium and added to the natural field soil to obtain 2000 cfu g1/soil of each species in treated soils. Ten local and international bean cultivars (Emerson, Dehghan, Joules, Akhtar, Naz, Sayad, Golden, Keshavarz, Daneshkadeh and Soheir L- 90) were sown into 50 infested and 50 non-infested pots; then their growth and yield productions were evaluated. ‘Naz’ was the most resistant cultivar, which produced the highest dry matter yield (175 g /15 plants) and the lowest yield reduction (9.3%), while ‘Joules’ had moderate production (110 g/15 plants) and loss (31.7%), and ‘Soheir L-90’ showed the highest susceptibility with the lowest (60 g/15 plants) and highest yield loss (52%). Thus, the results show the most important bean cultivar resistant to Fusarium decline disease, which is significant in favor of yield productions. Key words: Bean, decline, resistance, Fusarium