Grain Yield Of Cultivars Research Articles

Evaluating a new intercrop model for capturing mixture effects with an extensive intercrop dataset

Cereal-legume intercrops have numerous advantages over monocultures. However, the intercrop’s performance depends on the plant genotypes, management, and environment. Process-based agro-ecosystem models are important tools to evaluate the performance of intercrop systems as field experiments are limited in the number of treatments. The objective of this study was to calibrate and evaluate a new process-based intercrop model using an extensive experimental data set and to test whether the model is suitable for comparing intercrop management strategies. The data set includes all combinations of 12 different spring wheat entries (SW, Triticum aestivum L.) with two faba bean (FB, Vicia faba L.) cultivars, at two sowing densities, in three different environments. The results show that the intercrop model was capable of simulating the absolute mixture (intercrop) effects (AME) for grain yield, above-ground biomass, and topsoil root biomass, for both crops. However, the intercrop model does not perform better than a benchmark that ignores the intercrop effects when simulating plant height, fraction of intercepted radiation, volumetric soil water content, and subsoil root biomass. The intercrop model predicted reasonably well the differences between species and between SW cultivars for grain yield and aboveground plant biomass. Overall, the tested process-based model can be a useful tool for designing and pre-evaluation multiple combinations of crop management, species, and cultivars suitable for intercropping in diverse conditions.

Comparative analysis of wheat and barley yield performance across temperate environments

ContextA comparative analysis of grain yield performance of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) under different environments constitutes a way to identify restrictions in yield formation between both crop species. However, most of the previous studies on these field crops have been carried out in Mediterranean environments. ObjectiveThis study aims to compare the grain yield performance of wheat and barley across a wide range of temperate environmental conditions. MethodsWheat and barley yield databases from the national network of cultivar evaluation of Argentina were assembled. The database included 191 wheat cultivars (with early-, mid- and late-flowering length cycle), 140 barley cultivars, and 44 combinations of sites and years of the Argentine wheat and barley belt region. Average heading date variation among environments and crops was no more than 10 days. Crop grain yield comparisons were carried out using a regression analysis, benchmarking within each site-year the grain yield of each cultivar against the average grain yield of all crop cultivars (i.e., environmental index). ResultsThere were no differences in grain yield between wheat and barley for all data, but the behavior between crop species changed with the length of the wheat cycle (i.e., early-, mid-, or late-flowering cultivars). Barley portrayed a greater grain yield than early-flowering wheat under low-yielding environments (< 6060 kg ha−1), but this advantage vanished as the yield environment improved. Mid-flowering wheat showed a similar grain yield to barley across temperate environments. Lastly, late-flowering wheat outperformed barley mainly in high-yielding environments (> 6138 kg ha−1). Grain number m−2 was the main numerical component that explained variability in grain yield. The relative contribution of the yield numerical components differed between species, having barley lower grain number m−2 but a greater grain weight than wheat. ConclusionsThe comparison of the grain yield performance between species represents a strategy to adjust the rotation system, being a critical factor in considering the variability in the crop growth cycle.

Soil compaction development facilitated the decadal improvement of the root system architecture and rhizosheath soil traits of soybean in the North China Plain

Machinery agriculture has increased crop yield but induced soil compaction worldwide in the last decades. The crop yield increase is partly attributed to high-yielding crop breeding, but the effects of emerging soil compaction on the selection of root system traits and its impact on yield increase remain unclear. The objectives of this study were 1) to identify the effects of soil compaction on grain yield and root system architecture and rhizosheath soil traits of soybean (Glycine max (L.) Merr.) at the full-bloom stage, 2) to understand whether and how the development of soil compaction affected the selection of merit root and rhizosheath soil traits through crop breeding and contributed to soybean grain yield increase. Thirty-four most popular soybean cultivars released before and after the wide use of agricultural machinery in the North China Plain were grown in the fields without (NOM) and with (COM) applied soil compaction in 2017 and 2018. The phenotypes of root system, including rhizosheath soil, of soybean, were separated by soil compaction and cultivar release period, confirming the development of soil compaction and its impacts on the co-development of rhizosheaths with the root system of soybean. The correlation with the year of release of the cultivar demonstrated that 21 out of the 24 measured traits were selected by crop breeding. Multivariate analysis of the variance demonstrated that the selection of thinner hypocotyl, more root tips, and denser rhizosheath soil were relevant to the soil compaction development. The selection of shorter plant height, larger root biomass and area, thinner root tip, thicker taproot, and rhizosheath soil mass were likely relevant to the experimental year factor caused by drought or its associated change in nutrient availability. Most of the selected traits increased the resistance or the resilience to soil compaction and nine of them correlated with the grain yield of cultivars released at different periods. These results for the first time suggested that crop breeding increased grain yield partly by increasing the resistance and resilience to soil compaction. Soil compaction could be considered in a future breeding program design to increase crop breeding efficiency by selecting resistant and resilient root traits.

Varietal Differences in the Root Systems of Rice (Oryza sativa L.) under Drip Irrigation with Plastic Film Mulch

With the escalating water scarcity in agriculture, a novel water-saving technique has emerged: drip irrigation with plastic film mulch (DI). Root function is crucial for sustaining rice production, and understanding its response to DI is essential. However, few studies have evaluated root systems in rice varietals and examined which kind of root system contributes to improving rice grain yield and water productivity in DI. If varietal differences of root reactions for water regimes were made clear, it might be more effective to find suitable varieties for DI and to improve grain yield in the DI system. To fill this knowledge gap, we conducted a two-year field experiment comparing two irrigation systems: continuous flooding (CF) and DI. We analyzed their effectiveness with four rice cultivars, including upland, F1 lowland, animal feed lowland, and lowland cultivars. Vertical root distribution, root bleeding rate, photosynthetic-associated parameters, water productivity, and yield performance were analyzed. In our study, the average grain yield of cultivars in the DI system (6.4 t/ha) was equivalent to those in the CF system (6.6 t/ha). The average water productivity under DI (0.34–0.75 kg m−3) demonstrated significant water-saving potential, saving approximately 35% of the total water supplied, resulting in higher water productivity compared to CF (0.27–0.51 kg m−3). Among the cultivars, the deep root weight of the upland cultivar significantly increased by 51% under DI compared to CF. The deep root ratio was positively correlated with the transpiration rate, grain yield, and water productivity, suggesting its contribution to high transpiration, thus maintaining a high carbon assimilation rate that results in high yield and water productivity. Therefore, deep roots are a notable trait corresponding to high yield under DI, and should be considered for the development of rice growth models for DI and the breeding of aerobic-adapted cultivars.

Drought resistance of introgressive spring common wheat lines with genetic material of tall wheatgrass

Background. To breed drought-resistant cultivars of common wheat1 (Triticum aestivum L.), it is important to use the gene pools of its relatives, including tall wheatgrass Thinopyrum ponticum (Podpěra) Z.-W. Liu &amp; R.- C. Wang (= Agropyron elongatum (Host) Beauv.). Materials and methods. The introgressive lines of spring common wheat with T. ponticum genetic material and standard cultivars were studied in the field in the southern forest-steppe of Western Siberia using generally recognized methods. The ecological plasticity of cultivars and introgressive lines by grain yield and yield components was calculated according to the method of S. A. Eberhart and W. A. Russell. During the research period, there was a prolonged drought in 2012, and irregular short severe droughts occurred in 2013, 2014, and 2017. Results. An analysis of the ecological plasticity of standard cultivars adapted to the regional conditions showed that cv. ‘Pamyati Azieva’ corresponded to the extensive type, and cvs. ‘Duet’, and ‘Erythrospermum 59’ corresponded to the intensive type. Under drought conditions, the grain yield of cv. ‘Pamyati Azieva’ was determined by the stable development of productive tiller number, seed number and grain yield per main ear, but plasticity in 1000 grain weight was observed. Cvs. ‘Duet’ and ‘Erythrospermum 59’ showed ecological plasticity due to the adaptive development of two or three yield components. Introgressive lines exceeded the standard cultivars in grain yield (1.1–2.2 times) in dry seasons. Five lines were similar to cv. ‘Pamyati Azieva’ in plasticity and stability, and under drought conditions they demonstrated high and stable development of three or four yield components. The intensive lines formed their yield due to the compensatory development of three yield components in different combinations. Conclusion. Introgressive lines with T. ponticum genetic material are valuable for breeding spring common wheat cultivars with various drought-adaptation mechanisms.

Rice Cultivar Renewal Reduces Methane Emissions by Improving Root Traits and Optimizing Photosynthetic Carbon Allocation

Cultivar renewal (CR) contributes greatly to rice yield increase in China and even in the world. However, few studies were focused on the impact and mechanism of CR on field methane (CH4) emissions. A 2-year field experiment was conducted using 14 typical japonica rice cultivars released in the Yangtze River Basin of China during the last 70 years. The grain yield, root morphophysiological traits and their relationships with CH4 emissions were examined. The results showed that the grain yields of cultivars in the 1960–2010s increased by 18.8–93.9% while the CH4 emissions decreased by 9.5–41.2% compared with the 1950’s cultivars. The daily and cumulative CH4 emissions during the panicle differentiation stage (PD) were reduced significantly, which contributed greatly to the CH4 mitigation of the whole growing season. The CR notably increased root biomass, root/shoot ratio, root oxidation activity, and the total organic carbon in root exudates (ETOC), and decreased the ratios of ETOC/yield, ETOC/root biomass and ETOC/shoot biomass. Nitrogen fertilizer applied during panicle differentiation could improve the root physiology and decrease the ETOC/yield and ETOC/root, therefore reducing CH4 emissions. Our findings illustrated that CR reduced CH4 emissions by improving root traits and by optimizing the photosynthate allocation to biomass and grain yields. Applying nitrogen fertilizer during panicle differentiation could further mitigate the CH4 emissions in paddies.

Genotypic Performance of Kenyan Rice Cultivars for Grain Yield and Quality

Rice is the third most important staple food in Kenya after maize and wheat and it is mostly grown by small scale farmers both for food and cash under irrigated and rainfed production systems. In this study, fourteen F 2.3 segregating populations together with their parental lines, were evaluated during the long and short rainy seasons of 2016/2017 at the Mwea Research Station (KALRO) in a randomized complete block design of three replications for grain yield, quality and agronomic traits. There were significant differences among genotypes for all the traits studied. Genotypes, Nerica 1, Nerica 2 and Basmati-370 matured earliest, whereas genotype, Basmati-370 gave the highest grain yields in both seasons. The F1 generations of crosses of Dourado x Nerica 3 and Mwur 4 x Nerica 3 had the highest positive Specific Combining Ability (SCA) gene effects for panicle length, days to flowering and grain yield. However in the F 2.3 generations, the progenies of Nerica 2 x Basmati-370 and Nerica 3 x Basmati-370 had the highest grain yields. Generations of Nerica 10 x Mwur 4 crosses, had the longest grains whereas the Basmati-370 genotype had the strongest aroma. Generations of NERICA 3 x Basmati 370 and NERICA 2 x Basmati 370 crosses were of mild aroma, but those of K1-99 x KOMBOKA and NERCA 10 were non aromatic. Grain yield was positively significantly correlated with number of productive tillers, number of filled grains and 1000 grain weight indicating that these traits could serve as secondary selection indices for yield. It is inferred that breeding rice cultivars with improved traits for grain yield, long grain and strong aroma would benefit from the utilization of parental and population germplasm identified in this study, in the pursuit of filling the current rice production deficit in the Kenyan consumer markets.

Effects of supplemental irrigation on the accumulation, partitioning, and remobilization of nitrogen, yield and water use efficiency of wheat cultivars

In the Mediterranean, unbalanced precipitation distribution causes drought stress in rainfed wheat cultivation. Under such conditions, supplemental irrigation (SI) is a highly efficient practice to reduce the adverse effects of drought stress and improve yield. The present study aimed to assess the effects of SI on traits related to N accumulation and remobilization, chlorophyll concentration, yield and yield components, and water use efficiency (WUE) in different cultivars. Two field experiments with four irrigation levels (I0= rainfed, I1= SI at booting stage, I2= SI at booting and anthesis stages, I3= SI at booting, anthesis, and grain filling stages) and five cultivars (Rejaw, Sardari, Homa, Azar2, and Sirwan) was conducted during the 2015–2016 and 2016–2017 wheat growing seasons. Overall, results showed that SI notably had a positive effect on chlorophyll concentration, N content of plant parts, N remobilization (NR), grain number per spike, 1000-grain weight, biological yield, and grain yield in cultivars. Although the grain yield in the three SI treatments was 237.1 kg ha−1 and 630.4 kg ha−1 more than the other two (I2) and one (I1) SI, respectively, but the WUE was slightly lower in this treatment. The cultivars exhibited apparent differences in their responses to SI. The Sirwan cultivar showed a higher reaction to SI amongst cultivars. The highest N remobilization efficiency (NRE) was observed in I1 (73.69%) and I0 (73.34%) irrigation treatments. Sardari (74.03%) and Azar2 (73.60%) cultivars had higher NRE than other cultivars. The minimum contribution of NR to grain appeared in the I3 treatment (74.54%).

Optimizing irrigation and nitrogen fertilization of Iranian sesame cultivars for grain yield and oil quality

The impacts of water deficit stress, nitrogen (N) application rate and cultivar and their combination on sesame seed quality have not been previously studied. Hence, field experiments were conducted in a semi-arid area of Iran during the 2016 and 2017 growing seasons. The experiments were carried out in a randomized complete block design arranged in split factorial with three replications. Water deficit and full irrigation regimes were allocated to the main plots and factorial arrangement of sesame cultivars (Naz, Oltan and Dashtestan) and N rates (0, 60 and 120 kg N ha−1) were randomized to the sub-plots. The results indicated that an increase in N rate (0–120 kg N ha−1) could enhance sesame grain yield by 62 %, 112 % and 70 % under full irrigation conditions and by 32 %, 55 % and 67 % under water deficit irrigation conditions in Naz, Oltan and Dashtestan cultivars, respectively. Water deficit irrigation caused a considerable reduction in sesame seed oil content. This study obtained the highest unsaturated fatty acids when the Dashtestan cultivar was fully irrigated and treated with 120 kg N ha−1. The lowest amount of saturated fatty acid was achieved when full irrigation accompanied with 60 kg N ha−1 in Naz cultivar. The results demonstrated that water deficit irrigation reduces linoleic, oleic and stearic fatty acids and increases palmitic and linolenic fatty acids. Also, N application caused a significant increase in oleic and stearic fatty acids and significantly reduced linoleic and palmitic fatty acids. Overall, although plants’ genetic background is the most critical factor determining the oil content and fatty acid composition, environmental factors including water and N availability significantly affect fatty acid composition in sesame cultivars.

Studies on Correlation and Path Analysis in Linseed (Linum usitatissimum L.) Over Locations in Mid-hills of North-Western Himalayas

Background: Seed yield is a very important trait for selection but shows low heritability and hence is difficult to improve. Since the productivity of linseed (Linum usitatissimum L.) in India as well as Himachal Pradesh is low in comparison to other major linseed growing countries and states, improvement in cultivars for grain yield is a must. Therefore, the present study was aimed for studying the character associations in linseed genotypes for seed yield over locations. Method: The experiment was conducted during rabi 2019-2020. The experimental material for the present investigation comprised of 52 linseed genotypes grown over three locations in Himachal Pradesh i.e. Linseed Experimental Farm, CSK HPKV, Palampur (1290 m amsl), Shivalik Agricultural Research and Extension Centre, Kangra (700 m amsl) and Hill Agricultural Research and Extension Centre, Dhaulakuan (468 m amsl). Randomized block design with three replications was used. Phenotypic and genotypic correlation coefficients were worked out as per the procedure outlined by Burton and De Vane (1953) and Johnson et al. (1955). Direct and indirect effects of component traits on grain yield were worked out using correlation coefficient of various traits as suggested by Wright (1921) and elaborated by Dewey and Lu (1959). Result: Correlation studies indicated highly significant positive correlation for seed yield with 1000 seed weight (0.965**) followed by harvest index (0.801**), secondary branches (0.585**) and a significant correlation with biological yield (0.269**). Seed yield exhibited a non-significant positive correlation with seeds per capsule. However, a negative significant correlation was observed for seed yield with days to 50 per cent flowering and number of primary branches. The path coefficient analysis indicated that 1000 seed weight exhibited maximum positive direct effect with seed yield (0.741) while others had a low direct effect. The significant positive correlation of number of secondary branches and harvest index with seed yield was mainly due to indirect effect via 1000 seed weight indicating that 1000 seed weight is the most important trait for the improvement of grain yield in linseed as per the present study.

Yield performance of oat cultivars in response to sowing dates and densities

Adjustment of seeding density oriented by genotype and conditions of the growing environment may favor growth, development and yield performance of the oat crop. This study aimed to evaluate the growth, lodging, yield components, and grain yield of oat cultivars grown at different sowing dates and densities. Two independent experiments were conducted at two sowing dates (May 5 and June 24) in Londrina-PR under a randomized block design in a 4 × 2 factorial scheme, with four replications. Treatments consisted of four sowing densities (180, 240, 300, and 360 viable seeds m−2) and two cultivars (IPR Afrodite and IPR Artemis). Plant height, number of panicles.m−2, number of spikelets per panicle, number of grains per spikelet, number of grains per panicle, thousand-grain weight, plant lodging, and grain yield were evaluated. The data were submitted to the analysis of joint variance for sowing dates, separately for the cultivars. The averages of sowing dates were compared by the F test and densities submitted to polynomial regression analysis up to 2nd degree, at 5% probability. The first sowing date favors most yield components and grain yield of the cultivars IPR Afrodite and IPR Artemis. In contrast, the number of panicles m−2 was reduced during this growing season for both cultivars. The late sowing date for the IPR Artemis cultivar resulted in a high percentage of lodging at all evaluated densities. However, this phenomenon is more intense at higher sowing densities during the first sowing date. Yield components and grain yield varied according to sowing dates and densities and the cultivar. The highest grain yield of the cultivar IPR Afrodite at the first sowing date was achieved with a lower sowing density than in the later date. However, the highest grain yield of the IPR Artemis cultivar was achieved at density of 280 viable seeds m−2, regardless of the growing season.

Evaluation of Local Bread Wheat Cultivars for Grain Yield and Its Attributes at Different Sowing Dates under Assiut Conditions

The current research aimed to evaluate and select bread wheat stable cultivars with high ‎productivity across diverse sowing dates. Fourteen wheat cultivars were grown in a randomized ‎complete block design with three replicates at six sowing dates during two successive seasons of ‎‎2018/2019 and 2019/2020 representing twelve environments. The cultivars were evaluated for grain ‎yield and its attributes. Highly significant differences were obtained among the wheat cultivars, ‎sowing dates, and their respective interaction for all measured traits. The highest grain yield (2.992-ton ‎fed-1) was recorded on 30th November, after this date, each day delay in sowing of wheat onward ‎decreases grain yield at the rate of 21 kg fed-1 day-1. Overall, the cultivar Gemiza 11 gave the highest ‎grain yield with an average of 2.861 ton fed-1, recorded the highest 1000-GW with an average of 47.73 g, ‎highest straw yield with an average of 8.303-ton Fed-1, and was the earliest cultivar with a mean heading ‎date of 92.9 days. According to GGE biplot results, Gemiza 11, Gemiza 9, and Sakha 94 ranked in the ‎first order as high-yielding cultivars and had greater stability level overall sowing dates under ‎Assiut conditions. The most adequate cultivars for sowing in the first half of November (1st -15th ) ‎are Misr 2, Sids 12, Sakha 95, Gemiza 9, and Gemiza 11. Also, Sakha 94, Gemiza 9, and Gemiza 11 ‎can be sown after 30th November because they produce a satisfied yield, have good stability, and ‎can be considered as late sowing tolerant.‎

Phenotypic and Physiological Evaluation of Wheat Genotypes under Non-Saline and Saline Soil Conditions

This study was conducted to assess the effect of soil salinity on leaf area (LA), the number of days to flowering (DF), plant height (PH), and grain yield. Overall, 60 wheat genotypes were used, including 49 CIMMYT elite lines and 11 commercially grown Egyptian wheat cultivars. During two growing seasons (2017 and 2018), the genotypes were grown in non-saline (S0) and saline (S1) soils. A randomized complete block design with three replicates was used in a split-plot arrangement. Salinity levels were randomly assigned to the main plots, while genotypes were randomly assigned to the subplots. The obtained results showed that the saline soil adversely affected the evaluated genotypes. Furthermore, a highly significant effect of genotypes × salinity was observed on grain yield and its attributed traits. Based on salinity indices results, some of the imported wheat genotypes outperformed the Egyptian cultivars in grain yield under salinity stress conditions. The results further indicated that Sakha-93, C-31, and C-40 were the most salt-tolerant genotypes. The best performing line among the CIMMYT lines was C-31, which recorded the highest grain yield under none-saline and saline soil in the two seasons of study.

Genetic Gain in Wheat Grain Yield and Nitrogen Use Efficiency at Different Nitrogen Levels in an Irrigated Hot Environment

Improved nitrogen use-efficient cultivars could be the most economically beneficial and environmentally friendly approach to reduce pollution associated with excessive N fertilization. The performance and genetic gain in grain yield and nitrogen use efficiency (NUE) of a historical set of 12 bread wheat cultivars released for a heat-stressed environment were investigated at four N levels (0 (N0), 43 (N43), 86 (N86), and 129 (N129) kg/ha) for two seasons. Averaged across seasons, increasing N level from N0 to N43, N86, and N129 resulted in yield increases ranging from 4−45%, 13–69%, and 34–87% at N43, N86, and N129, respectively. These yield increases were associated with increases in biomass (r = 0.86, P&lt;0.01). Regressing grain yield of cultivars released during 1960 to 2006 against the year of release showed no trend at N0 and positive nonsignificant trends at N43;. however, significant positive trends were found at N86 and N129 with genetic gain rates of 12.65 and 15.76 kg ha−1 year−1, respectively. This gain was associated with progresses in harvest index (HI) at N43, N86, and N129 but not at N0. On the other hand, during the period from 1960 to 1990, the genetic gain in grain yield at N86 was 24.5 kg ha−1 year−1. Regressing NUE against the year of release showed significant linear trends at N86 and N129 (R2 = 0.511 and R2 = 0.477, respectively), but not at N43. The results indicate that breeders improved grain yield and NUE over 46 years under the heat-stressed environment of Sudan although the rate of increase in yield has been slowed down in recent years. Further improvement in NUE might require broadening the genetic diversity and simultaneous evaluation at low and high N levels.

Genotype x environment interaction analysis of Triticum aestivum L. for yield components

Abstract. Genotypes performance changes due to environmental pressures or stresses and differences in their ability to adapt to the stress factors. Drought is the main abiotic stress factor affecting bread wheat yield and yield component. The experiment was carried out in the experimental field of Trakia Agricultural Research Institute, Edirne (Turkey), in 2008-2009 and 2009-2010, and 15 wheat genotypes were planted in RCBD in a split-plot with three replications. The main plots were assigned to five moisture regimes, which included 3 drought stress environments, one non-stress and one non-treatment environment. Principal component analysis (PCA) and cluster analysis were used to determine genotypes environment interaction. Grain yield, biological yield, harvest index, spike number per square meter, kernel and spikelet number per spike, length of spike and plant height were investigated. PCA indicated that the first (46.31%) and second (25.32%) components justified 71.63% of variations in the investigated yield parameters of the genotypes. Based on GGE biplot results, Kate A-1 and Tekirdağ genotypes were determined as the most stable cultivars for grain yield. Mean values of the genotypes varied between 3830-6583 kg ha-1 for grain yield, 20170-25394 kg ha-1 for biological yield, 68.6-110.9cm for plant height, 30.2-38.3 for kernel number in spike, 328.8-486.6 for spike number per square meter and 6.57-9.17cm for spike length. Clusters I and II were more clearly separated. In the first group of clusters 6 genotypes are located including one line and five cultivars. In the second group of clusters 8 genotypes are located including five advanced lines and four cultivars.

Prinos i kvalitet zrna ozimog dvoredog ječma na kiselom zemljištu

The experiment was established at the experimental field of the Dr. Đorđe Radic Secondary School of Agriculture and Chemistry in Kraljevo (Serbia) during the 2010/11, 2011/12 and 2012/13 growing seasons. The objective of the research was to evaluate the effect of genotype and the environment on the grain yield of winter barley cultivars (‘Jagodinac’, ‘Maksa’, ‘Rekord’, ‘NS 565’ and ‘NS 525’). The following characteristics were analysed: grain yield, 1,000 grain weight, test weight and plant height. The average grain yield of all cultivars in the 2010/11 growing season was significantly greater than in the following years, mostly as the result of highly favourable weather conditions at major stages of plant development. ‘Jagodinac’, ‘NS 565’ and ‘NS 525’ gave significantly higher grain yields in all years compared to ‘Maksa’ and ‘Rekord’. Averaged across years, significantly higher values for 1,000 grain weight and test weight were found in ‘NS 565’ and ‘Rekord’, respectively. In all years, plant height was significantly greater in ‘Jagodinac’ than in the other cultivars. Different responses of cultivars to variable agroenvironmental conditions in terms of 1,000 grain weight and test weight require the use of a number of cultivars in the crop structure.

Competition among wild rice, landrace, improved cultivar and F1 hybrid rice

Four genotypes, namely Oryza rufipogon, F1 of IR68888A/Chaite-6, Chaite-6 and Ratodhan were grown in crop and competition environment at Rampur, Nepal to study the effect of genotypes mixture on the characters. Univariate, multivariate and correlation methods of analysis were applied. Seven characters namely panicle length, panicle number, grain yield, harvest index, internode length and leaf width showed significantly different response in crop and competition environment. The performance of cultivar was poor in competition environment than hybrid and wild rice. Hybrid and wild rice showed longer panicle length in competition environment. Significant reduction in panicle number was found in cultivars. The pattern of tiller number over the growth period showed that the competition started after 50 days of seeding. Grain yield of cultivars was significantly reduced in competition environment. Considering the most important characters, hybrid was best competitor and local landrace (Ratodhan) was poorest competitor. Significant variations in culm characters were not found between two environments but leaf characters varied significantly. Highest increment in plant height was found in F1 grown in competition than crop environment. Relationship between characters was affected by growing environment. Among 162 pairs of characters r-value of six and 36 pairs were highly significant different from zero in crop and competition environment respectively. Multivariate analysis indicates that growing environment does not suppress the genetic characters. Competition among the tested genotypes exists even in the recommended spacing. Competition should be studied in detail planting at different spacing.

Assessing Grain Yield and Quality Traits Stability of Spring Wheat Cultivars at Different Crop Management Levels

Eleven spring wheat cultivars were compared in terms of the stability of their grain yield and grain quality. The cultivars’ stability was evaluated separately at two different crop management levels — moderate-input management and high-input management. Three stability models were used for the two crop management levels based on a linear mixed model framework with restricted maximum likelihood. The Shukla model was the most appropriate for the evaluation of stability of tested spring wheat cultivars. The thousand-grain weight, starch content, Zeleny sedimentation value and test weight were characterized, and the stability ranking cultivars at moderate-input management level was mostly consistent with the rank of cultivars 24 for high-input management level. For grain yield, grain protein content and wet gluten content, the stability rankings were not consistent. Cultivars ‘Monsun’ and ‘Parabola’ are the most stable cultivars for grain yield in moderate-input management and high-input management, respectively. Cultivar ‘Hewilla’ was the stable cultivar for all quality traits at moderate-input management. Cultivar ‘Arabella’ was the most stable cultivar at high-input management level.

Influence of crop geometry and cultivars on growth, yield and production efficiency of dry direct-seeded rice (Oryza sativa L.)

A field experiment was conducted during kharif (summer) season of 2014, aim of the experiment was to investigate suitable crop geometry and cultivar and their influences on performance of dry direct-seeded rice (Oryza sativa L.), experimental treatments were consisting of 15 treatments, namely, main plots: five cultivars (MTU 7029, NDR 97, HUR 105, HUR 4-3 and PRH-10) and sub-plots: three crop geometry’s (20 x 10, 20 x 20 and 25 x 25 cm2). All the data recorded were statistically analyzed using the standard procedures of split-plot design. The results indicated that amongst cultivars, aromatic rice hybrid PRH-10 recorded significantly more grain yield (5582.32 kg/ha) than cultivar HUR 4-3 (4612.99 kg/ha) and NDR 97 (3397.82 kg/ha), whereas; it was statistically comparable with cultivar MTU 7029 (5489.24 kg/ha) and HUR 105 (5022.03 kg/ha). The cultivar PRH-10 also registered higher gross return (105771.9 `/ha), net return (66389.08 `/ha) and production efficiency (592.76 `/ha/day) than the remaining cultivars. The higher grain yield of PRH-10 over these cultivars was due to considerable improvement in most of its yield attributing characters like panicle length (27.92 cm), a number of grains/panicle (178.70) and test weight (26.35 g). In a case of crop geometry treatment, plant spacing of 25 x 25 cm2 recorded higher grain yield as compared to remaining plant spacing while the plant spacing of 20 x 10 cm2 recorded higher gross return, net return and production efficiency as compared to 20 x 20 and 25 x 25 cm2. Plant geometry plays an imperative role towards improving the grain yield of cultivars in direct seeded rice by optimal utilization of natural resources. Therefore, for getting higher net return and production efficiency, cultivar PRH-10 at plant spacing 20 x 10 cm2 can be raised in dry direct-seeded rice in Varanasi region of Eastern Uttar Pradesh.

Yield Gains in Extra‐Early Maize Cultivars of Three Breeding Eras under Multiple Environments

Core IdeasThe study determined genetic improvement in grain yield of the cultivars during the breeding eras, investigated trait associations, and identified high‐yielding and stable cultivars across multiple‐stress and non‐stress environments.The study revealed an annual genetic gain of 2.72 and 2.28% for the cultivars under multiple‐stress and non‐stress environments.Cultivars 2004 TZEE‐Y Pop STR C4, TZEE‐W Pop STR QPM C0, TZEE‐W Pop STR BC2 C0 of era 2 and TZEE‐W STR 107 BC1, TZEE‐W Pop STR C5, and 2012 TZEE‐Y DT STR C5 of era 3 were the highest yielding and stable across multiple‐stress environments while 98 Syn EE‐W from era 1, FERKE TZEE‐W STR, TZEE‐W Pop STR C3, TZEE‐Y Pop STR QPM C0 from era 2, and TZEE‐W Pop STR C5, 2009 TZEE‐OR2 STR QPM, 2009 TZEE‐W STR, TZEE‐Y STR 106, TZEE‐W DT C0 STR C5 from era 3 were the most outstanding across non‐stress environments.We conclude that substantial progress has been made in breeding for multiple‐stress tolerant extra‐early maize cultivars in West and central Africa.Availability of extra‐early maize cultivars has facilitated the expansion of maize production into savannas of West and Central Africa (WCA). Fifty‐six extra‐early maize cultivars of three breeding eras;1995 to 2000, 2001 to 2006, and 2007 to 2012 were evaluated for 2 yr under 24 multiple‐stress and 28 non‐stress environments in WCA. Objectives of the study were to determine genetic improvement in grain yield of cultivars developed during the breeding eras, and identify high‐yielding and s multiple‐stress and non‐stress environments. Yield gains from era 1 to era 3 under multiple stresses was associated with increased days to anthesis, reduced stalk lodging, and improved husk cover. Cultivars 2004 TZEE‐Y Pop STR C4, TZEE‐W Pop STR QPM C0, and TZEE‐W Pop STR BC2C0of era 2; and TZEE‐W STR 107 BC1, TZEE‐W Pop STR C5, and 2012 TZEE‐Y DT STR C5of era 3 were high‐yielding and stable across multiple‐stress environments while 98 Syn EE‐W from era 1, FERKE TZEE‐W STR, TZEE‐W Pop STR C3, and TZEE‐Y Pop STR QPM C0from era 2, and TZEE‐W Pop STR C5, 2009 TZEE‐OR2STR QPM, 2009 TZEE‐W STR, TZEE‐Y STR 106, and TZEE‐W DT C0STR C5from era 3 were outstanding across non‐stress environments and should be tested extensively and commercialized. Considerable improvement has been made in breeding for multiple‐stress tolerant extra‐early maize cultivars.