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Maize is a valuable crop with high genetic variability, and understanding this variability is essential for improving crop productivity and resilience to environmental stressors. This study evaluated the genetic variability and heritability of yield and yield-related traits among 27 drought-tolerant maize genotypes in a humid climate region of Southwestern Nigeria. The experiments followed rigorous agronomic, soil, and climatic requirements for maize cultivation. Our findings revealed significant genetic variability among the traits of the maize genotypes, particularly in the number of ears per plant, which had the highest genetic advancement as a percentage of the mean (68.25 % and 67.83 %) under both well-watered and drought conditions, respectively. This suggests that breeding programs targeting this trait could significantly improve maize productivity and resilience to drought stress. Additionally, most of the agronomic traits targeted were highly heritable with heritability values ranging from 0.76 to 0.99 under both environments where the genotypes were evaluated, thus indicating that selective breeding for these traits could lead to consistent improvements in maize yields over time. Overall, this study highlights the importance of evaluating yield-related traits’ genetic variability and heritability in maize breeding programs. Findings suggest that targeting the number of ears per plant in drought-tolerant maize genotypes as revealed in the study could be an effective approach for improving crop productivity and resilience in regions with variable moisture regimes.

Unpredictable weather vagaries in the Asian tropics often increase the risk of a series of abiotic stresses in maize-growing areas, hindering the efforts to reach the projected demands. Breeding climate-resilient maize hybrids with a crosstolerance to drought and waterlogging is necessary yet challenging because of the presence of genotype-by-environment interaction (GEI) and the lack of an efficient multi-trait-based selection technique. The present study aimed at estimating the variance components, genetic parameters, inter-trait relations, and expected selection gains (SGs) across the soil moisture regimes through genotype selection obtained based on the novelmulti-trait genotype-ideotype distance index (MGIDI) for a set of 75 tropical pre-released maize hybrids. Twelve traits including grain yield and other secondary characteristics for experimental maize hybrids were studied at two locations. Positive and negative SGs were estimated across moisture regimes, including drought, waterlogging, and optimal moisture conditions. Hybrid, moisture condition, and hybrid-by-moisture condition interaction effects were significant (p = 0.001) for most of the traits studied. Eleven genotypes were selected in each moisture condition through MGIDI by assuming 15% selection intensity where two hybrids, viz., ZH161289 and ZH161303, were found to be common across all the moisture regimes, indicating their moisture stress resilience, a unique potential for broader adaptation in rainfed stress-vulnerable ecologies. The selected hybrids showed desired genetic gains such as positive gains for grainyield (almost 11% inoptimal anddrought; 22% in waterlogging) and negative gains in flowering traits. The view on strengths and weaknesses as depicted by the MGIDI assists the breeders to developmaize hybrids with desired traits, such as grain yield and other yield contributors under specific stress conditions. The MGIDI would be a robust and easy-to-handle multi-trait selection process under various test environments with minimal multicollinearity issues. It was found to be a powerful tool in developing better selection strategies and optimizing the breeding scheme, thus contributing to the development of climate-resilient maize hybrids. [ABSTRACT FROM AUTHOR]

Unpredictable weather vagaries in the Asian tropics often increase the risk of a series of abiotic stresses in maize-growing areas, hindering the efforts to reach the projected demands. Breeding climate-resilient maize hybrids with a cross-tolerance to drought and waterlogging is necessary yet challenging because of the presence of genotype-by-environment interaction (GEI) and the lack of an efficient multi-trait-based selection technique. The present study aimed at estimating the variance components, genetic parameters, inter-trait relations, and expected selection gains (SGs) across the soil moisture regimes through genotype selection obtained based on the novel multi-trait genotype–ideotype distance index (MGIDI) for a set of 75 tropical pre-released maize hybrids. Twelve traits including grain yield and other secondary characteristics for experimental maize hybrids were studied at two locations. Positive and negative SGs were estimated across moisture regimes, including drought, waterlogging, and optimal moisture conditions. Hybrid, moisture condition, and hybrid-by-moisture condition interaction effects were significant (p ≤ 0.001) for most of the traits studied. Eleven genotypes were selected in each moisture condition through MGIDI by assuming 15% selection intensity where two hybrids, viz., ZH161289 and ZH161303, were found to be common across all the moisture regimes, indicating their moisture stress resilience, a unique potential for broader adaptation in rainfed stress-vulnerable ecologies. The selected hybrids showed desired genetic gains such as positive gains for grain yield (almost 11% in optimal and drought; 22% in waterlogging) and negative gains in flowering traits. The view on strengths and weaknesses as depicted by the MGIDI assists the breeders to develop maize hybrids with desired traits, such as grain yield and other yield contributors under specific stress conditions. The MGIDI would be a robust and easy-to-handle multi-trait selection process under various test environments with minimal multicollinearity issues. It was found to be a powerful tool in developing better selection strategies and optimizing the breeding scheme, thus contributing to the development of climate-resilient maize hybrids.

The effect of ageing and addition of lime, farm yard manure (FYM) and zinc (Zn) as amendments on different fractions of nickel (Ni), in soil after spiking with Ni was estimated over a 60-day incubation period. The soil was spiked with Ni @25 mg kg-1 soil through its nitrate solution. Lime, FYM and Zn were added @ 5%, 20 t ha-1 and 25 mg kg-1, respectively. The treated soil samples were incubated for 1, 45 and 90 days at field capacity and under submerged soil moisture regime. Significant decrease in the water soluble and exchangeable fractions of Ni with ageing was observed and it was in the order of 1day > 45 days > 90 days. The magnitude of this decrease was higher with the addition of amendments and it was in the order of lime > FYM > Zn > unamended soil. On the other hand, a temporal increase in organically bound, oxide bound and carbonate fractions of Ni with addition of amendments was observed, but the per cent distribution among these fractions varied. Residual fraction of Ni was not significantly affected by ageing, amendments and moisture regimes. Overall, soil moisture regime did not change the direction and pathways of transformations of Ni, but it increased the transformation rate. Submerged conditions showed higher metal reactivity compared with field capacity resulting in the pronounced transformation of Ni towards stable fractions. The results enable us to understand natural attenuation of Ni contamination and also to assess the effect of different amendments and moisture regimes on Ni transformations to work out the capacity of soil to serve as a source of supply of Ni. [ABSTRACT FROM AUTHOR]

The present paper focused on content, quality and composition of soil organic matter in different pedoclimatic zones of Bulgaria. The country has temperate continental climate with Mediterranean influence. There are six combinations of soil temperature and moisture regimes over the territory of Bulgaria, such as Thermic-Xeric, Mesic-Xeric, Mesic-Ustic, Mesic-Udic, Cryic-Udic and Pergelic – Udic. Typical soil types for Bulgaria are Chernozems, Luvisols. Vertisols, Cambisols, Phaeozems, Leptosols, Regosols, Planosols, Umbrisols and etc. Fifteen soil profiles were studied which are representative for the area. The content and composition of organic matter were determined according to the method of Kononova-Belchikova. The purpose of this study is to determine the influence of pedoclimatic conditions over soil organic matter content and composition of various areas with different soil cover, vegetation, management and etc. Grouping soil types in different soil temperature and moisture regimes shows that there are similarities in soil carbon content and composition. Soils developed under cooler and moister conditions accumulate more organic carbon. In such areas the content of organic carbon can reach about 255 t.ha-1 in a surface horizon and the type of humus is predominantly Fulvic. Respectively, soils developed under dry and warmer conditions have lower organic carbon content and the type of humus is usually Humic.

Drought is a major constraint in drylands for crop production. Plant associated microbes can help plants in acquisition of soil nutrients to enhance productivity in stressful conditions. The current study was designed to illuminate the effectiveness of desert rhizobacterial strains on growth and net-return of chickpeas grown in pots by using sandy loam soil of Thal Pakistan desert. A total of 125 rhizobacterial strains were isolated, out of which 72 strains were inoculated with chickpeas in the growth chamber for 75 days to screen most efficient isolates. Amongst all, six bacterial strains (two rhizobia and four plant growth promoting rhizobacterial strains) significantly enhanced nodulation and shoot-root length as compared to other treatments. These promising strains were morphologically and biochemically characterized and identified through 16sRNA sequencing. Then, eight consortia of the identified isolates were formulated to evaluate the growth and development of chickpea at three moisture levels (55%, 75% and 95% of field capacity) in a glass house experiment. The trend for best performing consortia in terms of growth and development of chickpea remained T2 at moisture level 1 > T7 at moisture level 2 > T4 at moisture level 3. The present study indicates the vital role of co-inoculated bacterial strains in growth enhancement of chickpea under low moisture availability. It is concluded from the results that the consortium T2 (Mesorhizobium ciceri RZ-11 + Bacillus subtilis RP-01 + Bacillus mojavensis RS-14) can perform best in drought conditions (55% field capacity) and T4 (Mesorhizobium ciceri RZ-11 + Enterobacter Cloacae RP-08 + Providencia vermicola RS-15) can be adopted in irrigated areas (95% field capacity) for maximum productivity of chickpea.

The present paper focused on content, quality and composition of soil organic matter in different pedoclimatic zones of Bulgaria. The country has temperate continental climate with Mediterranean influence. There are six combinations of soil temperature and moisture regimes over the territory of Bulgaria, such as Thermic-Xeric, Mesic- Xeric, Mesic-Ustic, Mesic-Udic, Cryic-Udic and Pergelic - Udic. Typical soil types for Bulgaria are Chernozems, Luvisols. Vertisols, Cambisols, Phaeozems, Leptosols, Regosols, Planosols, Umbrisols and etc. Fifteen soil profiles were studied which are representative for the area. The content and composition of organic matter were determined according to the method of Kononova-Belchikova. The purpose of this study is to determine the influence of pedoclimatic conditions over soil organic matter content and composition of various areas with different soil cover, vegetation, management and etc. Grouping soil types in different soil temperature and moisture regimes shows that there are similarities in soil carbon content and composition. Soils developed under cooler and moister conditions accumulate more organic carbon. In such areas the content of organic carbon can reach about 255 t.ha-1 in a surface horizon and the type of humus is predominantly Fulvic. Respectively, soils developed under dry and warmer conditions have lower organic carbon content and the type of humus is usually Humic. [ABSTRACT FROM AUTHOR]

Procura-se investigar a validade de um método de classificação de regimes de umidade, baseado na caracterização de diferentes "estados" da Camada Limite Atmosférica Tropical (CLAT), acima de uma área de floresta, de acordo com a metodologia proposta por Mahrt (1991). Para essas análises foram utilizados dados de radiossondagens e de uma torre micrometeorológica, coletados durante o período menos chuvoso da região, obtidos durante o experimento "COBRA-PARÁ" (realizado no período de 30/10 a 15/11 de 2006). A análise dos regimes de umidade consiste na representação em espaço de fase dos dados disponíveis da razão de Bowen (β), em função do parâmetro -h/L (onde h é a altura da camada de mistura turbulenta e L é o comprimento de Obukhov). Dependendo da localização dos dados nesse espaço foi possível caracterizar as seguintes classes: classe I - ar seco e instável; classe II - vento seco predominante; classe III - vento úmido; classe IV - condição úmida e instável; classe V - condensação de vapor d'água na superfície; classe VI - condição estável dominante; e classe VII -formação de orvalho induzido por radiação noturna resfriando a superfície. Das classes mencionadas, aquelas mais freqüentemente observadas em Caxiuanã, foram as III, IV e VI.We investigate the validity of a method of humidity regimes classification, based on different "states" characterization of the Tropical Atmospheric Boundary Layer (TABL), above a forest area, according to the methodology proposed by Mahrt (1991). To perform this investigation we used radiosonde information and micrometeorological tower data collected during the drier season of the region, during the experiment "COBRA-PARÁ" (carried out from 30/10 to 15/11, 2006). The analysis of moisture regimes is based on the "phase space" data representation, where the Bowen ratio (β) is plotted against the -h/L parameter (where h is the height of the turbulent mixing layer and L is the Obukhov length scale). According to the location of the data value in this "phase space" it was possible to identify the following classes: Class I - dry air and unstable conditions, Class II - dry wind, Class III - wet wind, Class IV - wet air and unstable conditions, Class V - occurrence of water condensation on the surface, Class VI - stable conditions predominance and Class VII - dew formation generated by nocturnal radiative losses with surface cooling. Among the mentioned classes, the III, IV and VI were the most frequently observed at Caxiuanã.

Persistence of spiromesifen in soil as affected by varying moisture, light, compost amendment, soil sterilization and pH in aqueous medium were studied. Degradation of spiromesifen in soil followed the first-order reaction kinetics. Effect of different moisture regimes indicated that spiromesifen dissipated faster in submerged soil ( t 14.3-16.7 days) followed by field capacity ( t 18.7-20.0 days), and dry soil ( t 21.9-22.9 days). Dissipation was faster in sterilized submerged ( t 17.7 days) than in sterilized dry ( t 35.8 days). Photo spiromesifen metabolite was not detected under different moisture regimes. After 30 days, enol spiromesifen metabolite was detected under submerged condition and was below detectable limit (<0.001 μg g) after 90 days. Soil amendment compost (2.5 %) at field capacity enhanced dissipation of the insecticide, and half-life value was 14.3 against 22.4 days without compost amendment. Under different pH condition, residues persisted in water with half-life values 5.7 to 12.5 days. Dissipation in water was faster at pH 9.0 ( t 5.7 days), followed by pH 4.0 ( t 9.7 days) and pH 7.2 ( t 12.5 days). Exposure of spiromesifen to different light conditions indicated that it was more prone to degradation under UV light ( t 3-4 days) than sunlight exposure ( t 5.2-8.1 days). Under sunlight exposure, photo spiromesifen metabolite was detected after 10 and 15 days as compared to 3 and 5 days under UV light exposure. [ABSTRACT FROM AUTHOR]

Background and Aims: Ecosystem recovery following disturbance requires the reestablishment of key soil biogeochemical processes. This long-term 7 year study describes effects of organic material, moisture, and vegetation on soil microbial community development in the Athabasca Oil Sands Region of Western Canada. Methods: Phospholipid fatty acid analysis was used to characterize and compare soil microbial community composition and development on reclaimed and natural forest sites. Additionally, we conducted a laboratory moisture manipulation experiment. Results: The use of forest floor material as an organic amendment resulted in a greater percent cover of upland vegetation and placed the soil microbial community on a faster trajectory towards ecosystem recovery than did the use of a peat amendment. The soil microbial composition within the reclaimed sites exhibited a greater response to changes in moisture than did the soil microbial communities from natural sites. Conclusion: Our research shows that the use of native organic amendment (forest floor) on reclaimed sites, and the associated establishment of native vegetation promote the development of soil microbial communities more similar to those found on natural forest sites. Additionally, soil microbial communities from natural sites may be more resistant to changes in soil moisture than those found on reclaimed sites. [ABSTRACT FROM AUTHOR]

Sustainable grain production in the Brazilian Savannah (Cerrado), relies on biological diversity and tillage improvement. The present practice of no-tillage, which depends on soil cover, includes few species, i.e., maize, millet, sorghum (Gramineae), soybean and common bean (Leguminosae). Quinoa, the Andean grain crop (Chenopodium quinoa Willd., Chenopodiaceae), has been introduced in the savannah to utilise residual moisture in double cropping, for mulch and grain production. Selected genotypes were grown in autumn, after soybean harvest, in Planaltina, DF, Brazil, located at 15o 36' S and 47o 12' W, elevation of 1,000 m.a.s.l. A randomised complete block experiment, with three replications, was used on an oxisol (Ferralsol, FAO), under residual moisture and supplemental irrigation regimes. Grain yield for, Q18 and Q24, was 2,200 and 1,153 kg ha-1 for respective irrigated and stressed condition. This character was positively associated with plant height and plant cycle. Early maturity genotypes had higher yields under stress than late, with few exceptions, like Q24, yielding 56% of its performance in sufficient water supply. Selection for drought tolerance and vigorous growth, combined to early maturity in main crop, to anticipate sowing, will contribute for commercial cultivation of quinoa in the tropics.

Summary 1. The effects of experimental long-term summer drought and irrigation on soil fauna were studied in a Norway spruce stand in south-western Sweden. The treatments, carried out over 8 and 10 years respectively, were chosen to simulate two scenarios of climate change, involving drier and wetter summers. 2. Different microarthropod communities developed in the different treatments. The abundances of enchytraeids, mesostigmatid mites and macroarthropod predators were all lowest in the drought plots. Drought decreased and irrigation increased the abundance and diversity of Oribatida. Drought decreased the abundance of Collembola. 3. The dominance structure of Oribatida and Collembola also changed, but less markedly. Drought affected community composition of both groups more than irrigation. 4. The study confirms that soil microarthropods can be useful environmental indicators, but their responses did not support the widely held view that deviations from a log-normal dominance structure indicates a stressed community. 5. The results also indicate that a drier climate with summer drought will lead to the local extinction of some soil animal species in this region. [ABSTRACT FROM AUTHOR]

Drought is a major constraint in drylands for crop production. Plant associated microbes can help plants in acquisition of soil nutrients to enhance productivity in stressful conditions. The current study was designed to illuminate the effectiveness of desert rhizobacterial strains on growth and net-return of chickpeas grown in pots by using sandy loam soil of Thal Pakistan desert. A total of 125 rhizobacterial strains were isolated, out of which 72 strains were inoculated with chickpeas in the growth chamber for 75 days to screen most efficient isolates. Amongst all, six bacterial strains (two rhizobia and four plant growth promoting rhizobacterial strains) significantly enhanced nodulation and shoot-root length as compared to other treatments. These promising strains were morphologically and biochemically characterized and identified through 16sRNA sequencing. Then, eight consortia of the identified isolates were formulated to evaluate the growth and development of chickpea at three moisture levels (55%, 75% and 95% of field capacity) in a glass house experiment. The trend for best performing consortia in terms of growth and development of chickpea remained T2 at moisture level 1 > T7 at moisture level 2 > T4 at moisture level 3. The present study indicates the vital role of co-inoculated bacterial strains in growth enhancement of chickpea under low moisture availability. It is concluded from the results that the consortium T2 (Mesorhizobium ciceri RZ-11 + Bacillus subtilis RP-01 + Bacillus mojavensis RS-14) can perform best in drought conditions (55% field capacity) and T4 (Mesorhizobium ciceri RZ-11 + Enterobacter Cloacae RP-08 + Providencia vermicola RS-15) can be adopted in irrigated areas (95% field capacity) for maximum productivity of chickpea. [ABSTRACT FROM AUTHOR]