Low Moisture Stress Research Articles

Biochemical and morpho-physiological insights revealed low moisture stress adaptation mechanisms in cotton (Gossypium hirsutum L.)

Cotton (Gossypium hirsutum L.) is a multipurpose crop. Abiotic stresses, especially extreme heat and drought, limit crop growth and thus reduce cotton yield by about 50%. In this study, 30 cotton genotypes were tested against low moisture stress in a pot experiment in triplicates along with control under wire house conditions. At the 3–4 leaf stage, different morpho-physiological and biochemical parameters were measured in order to select the low moisture stress-tolerant genotypes. For the selection of the best performing genotypes, Multi-Trait Genotype-Ideotype Distance Index (MGIDI) was used for the ranking of genotypes on the basis of multiple indices. For biochemical traits, 09 (TPC, TF, TSP, MDA, SOD, POD, CAT, APX, and Proline) out of 24 showed significant genotypic effects and were used for MGIDI. Eight genotypes (N-812 N-1296 N-696 N-377 N-121–896 N-T86, and N-3496) were observed to be best performing than others at 25% selection pressure (SI = 25%). For morpho-physiological traits, 14 out of 15 showed significant genotypic effects and used for MGIDI. Ten genotypes (N-1237 N-812 N-1296 N-696 N-9078 N-377 N-512 N-121 N-375, and N-896) were observed to be best performing at 35% selection pressure (SI = 35%). Six genotypes, i.e. N-812–1296 N-696 N-377 N-121, and N-896 were found common in both MGIDI analysis. In conclusion, three genotypes, i.e. N-696, N-896, and N-T86 proved to be most resilient to low moisture stress. Develop protocols, identified genotypes and markers that can be used for development of climate-smart cotton genotypes.

Multi Environment Trials and Adaption of Advanced Bread Wheat (<i>Triticum aestivum </i>L.) Genotypes in Low Moisture Stress Areas of Ethiopia

To predict bread wheat genetic potential across environments and adaption in low moisture stress wheat growing areas of Ethiopia. Multi-location trials were conducted in Ethiopia from 2020 to 2021 in main seasons. A total of advanced genotypes including the checks were arranged in randomized complete block design in a rectangular (row x column) array of plots with two replications. The results showed that, under the linear mixed model, the spatial and factor analytic models were efficient methods of data analysis for this study. By ranking average best linear unbiased prediction (BLUPs) within clusters, the 13 bread wheat environments were clustered into three mega environments (C1, C2, and C3) for the trait grain yield. This method used as a selection indicator, assisting in the selection of superior and adaptable types. The predicted performance of genotypes based on BLUP values averaged across correlated settings of C1 and C2, eliminating C3 due to low genetic correlation with the other trials and low genetic variation. Based on these clusters, the genotypes with the highest potential EBW192350 and EBW192369 were selected for a subsequent verification study that might potentially use them as a released variety. For genetic variance, the estimates for variance component parameters ranged from 0.069 to 2.896 and error variance, they ranged from 0.175 to 1.002. Therefore, increasing the application of this efficient analysis method will improve the selection of superior bread wheat varieties. The two genotypes can be further verified using national performance trials/ or verified in farmers’ fields for registration and commercialization.

Low temperature and excess moisture affect seed germination of soybean (Glycine max L.) under controlled environments

Cold and excess moisture pose a serious threat to soybean production especially during seed germination in short-season environments. In this study, the effects of low temperature and excess moisture stress on seed germination were investigated in 187 soybean accessions originating from 18 countries. The experiment used a combination of three temperature conditions (i.e., 20 °C/14 °C, 14 °C/10 °C, and 10 °C/10 °C day/night) and two moisture levels (i.e., normal and excess). The seed germinability traits measured included germination rate (GR), germination index, germination time, germination uniformity, and coefficient of velocity of germination. Overall, GR was lowest in the 20 °C/14 °C + excess moisture and germination time was longest in the 10 °C/10 °C + excess moisture. When compared with 20 °C/14 °C + normal moisture treatment, GR at 10 °C/10 °C + excess moisture decreased by 38%; germination time increased by 20 days; seed viability decreased by 83%; germination uniformity decreased by 70%; germination speed decreased by 73%. Differences in GR, germination index, and germination velocity under different treatments were affected by temperature, moisture, and their interaction. Variation in germination time uniformity was determined by temperature, with no significant effects of moisture conditions and the interaction of temperature and moisture. It was shown that the temperature–excess moisture interaction led to a sharp decrease in seed germination. Two genotypes including PI 603147 and PI 507702 were identified with a GR over 90% at 10 °C/10 °C + excess moisture. This study generated new knowledge and data to further the understanding of genetic resistance to cold and excess moisture stress in soybean.

Effect of combined use of supplementary irrigation, manure and P fertilization on grain yield and profitability of soybean in northern Nigeria

Declining soil fertility particularly phosphorus deficiency, low organic carbon, moisture stress and high cost of input are factors limiting soybean yield in the Nigeria savanna. Supplementary irrigation, nutrient application and inoculation with Bradyrhizobium could increase the grain yield of soybean. We evaluated the effects of Rhizobia inoculant, phosphorus fertilization, manure, and supplementary irrigation on the nodulation and productivity of a tropical soybean variety in two locations in northern Nigeria in the 2017 and 2018 cropping seasons. The treatments consisted of five input bundles: Supplementary irrigation +17.5 kg P ha−1 + 4 t ha−1 poultry manure + nodumax inoculant (S + P + M + I); 17.5 kg P ha−1 + 4 t ha−1 poultry manure + nodumax inoculant (P + M + I); 17.5 kg P ha−1 + nodumax inoculant (P + I); 17.5 kg PP ha−1 (P); and nodumax inoculant (I). Economic analysis was done to determine the benefit-cost ratio (BCR) for each input bundle. In Kano, the input bundle S + P + M + I produced mean number of nodules that were 38, 102, 200 and 352% higher than that of input bundles P + M + I, P + I, P and I, respectively. At Lere, the application of input bundle S + P + M + I increased mean number of nodules by 33, 81, 93 and 182% over that of input bundles P + M + I, P + I, P and I, respectively. Mean grain yield in Kano was greater for input bundle S + P + M + I over P + M + I, P + I, P and I bundles by 31, 50, 64 and 223%, respectively. In Lere, grain yield for input bundle S + P + M + I was higher than that of input bundles P + M + I, P + I, P and I only, by 27, 47, 41 and 184% respectively. The input bundle P + M + I produced the highest BCR (1.4) in Kano and application only of P produced the highest BCR (1.3) in Lere. Supplementary irrigation was not found to be profitable due to the high cost of supplementary irrigation.The application of P with or without manure/inoculant is recommeded for profitable soybean production in the savannas of Nigeria.

Minimizing the Effect of Low Moisture Stress in Pearl Millet (Pennisetum glaucum L.) by Regulating Growth, Yield and Antioxidant Defense System Via Foliar Applied Silicon

Most abundant element on earth crust is silicon (Si), easily available and mostly used in farming against low moisture stress in arid regions. Thus, a pot experiment was accomplished for identifying the beneficial effects of Si on the growth, productivity and activity of antioxidants in pearl millet. The millet plant was arranged in complete randomized design (CRD) under normal and drought stress condition and treated with four level of Si (0.0, 2.5, 5.0, and 7.5 mmol/L). The results revealed that foliar 5.0 mmol/L of foliar applied Si improved the growth traits (leaf fresh weight 18.99%, stem fresh weight 9.34%, root fresh weight 28.75%, root dry weight 33.11%, plant height 21.7%, and stem diameter 28.26%) and yield traits (no. of grains per spike 9.22%, and grain yield 15.89%). While it enhances the activity of antioxidants as (catalase 8.1%, peroxidase 36.84%, and ascorbate peroxidase 17.16%). In short, foliar application of Si is an effective strategy for improving all the growth and yield traits as well as some of the antioxidants in the presence of low moisture stress in pearl millet crop. In this manner, foliar applied 5.0 mmol/L of Si will be recommended as the best doze for controlling the negative impact on pearl millet crop. Hopefully, the findings of this research will be helpful for the future research against stress related challenges.

Root responses under water deficit stress: unraveling the impact on wheat crop and the ameliorating role of brassinolide

Aim: To identify changes in root system architecture traits of wheat due to exogenous application of epibrassinolide for the alleviation of negative impact of low moisture stress in wheat crop. Methodology: On the basis of growth performances one set of contrasting wheat genotypes were identified (HD-2733, relatively stress tolerant and DBW-187 relatively stress sensitive). Similarly, brassinosteroids (BRs) concentration was selected by pilot experiments, wherein 0.01mM performed best among all. Taking all these results into consideration, four treatments (T0=well-watered, T1=water deficit, T3=EBL + well wateredandT4=EBL + water deficit) were maintained for evaluation of root architectural traits, biomassand grain yield per plant. Results: The tolerant genotype (HD-2733) showed better tolerance in almost all root traits and in yield as compared to the sensitive genotype (DBW-187). epibrassinolide under water deficit condition was found to be effective as the root trait values were higher for root length, root volume, root surface area and root biomass under EBL+ water deficit treatment as compared to water deficit. Shoot biomass was highly sensitive to water deficit as the biomass allocation under water deficit was more towards root as compared to shoot. Interpretation: Epibrassinolide can be a potent biochemical to improve the root characteristics as well as yield per plant. Seeds of tolerant genotype treated with 0.01m M EBL even under low moisture stress can be recommended. Key words: Epibrassinolide, Root system, Wheat, Water deficit

Registration of New Bread Wheat Variety (Biftu) for Low to Mid-Altitude Wheat-Producing Areas of Ethiopia

In Ethiopia, wheat (Triticum Sp.) is cultivated on a total area of 2.1 million (1.7 million ha for rain fed and 0.4 million ha for irrigated areas) hectares of land; the annual total production is 6.7 million tons of grains during 2022. Recently released commercial wheat varieties have higher genetic gain for economic trait than the older varieties. Forty-seven advanced genotypes and three standard checks were tested across different environments from 2019 to 2020 in Ethiopia. The genotypes were arranged in row column design with three replications. Analysis of variance and mean separation were carried out to differentiate the significance difference in genotypes. The results revealed that the advanced genotypes viz. BW173528 and EBW17-365 had significantly higher for grain yield than the other genotypes. In addition, BW173528 has better diseases resistance than the checks; Deka, Kakaba and Kingbird. Therefore, this genotype was tested and verified on farmers’ fields in 2021. Based on its performance and good quality traits the advanced line BW173528 was released for production in low moisture stress areas of Ethiopia and named as: Biftu.

Impact of Biotic and Abiotic Stress on Survival of Lac Insects Kerria lacca Kerr. on Pigeonpea (Cajanus cajan (L.) Millsp)

Cajanus cajan is generally grown in rainfed condition. The crop is also a good annual host plant of lac insect. C. cajan is widely reported to have biotic stress due to insect pests on it. Lac insect is phloem sap feeder and hence imparts biotic stress. The present field study was conducted to evaluate the percent survival of lac insects on C. cajan by adjusting different levels of biotic and abiotic stress on the host plant. The biotic stress due to insect pests on C. cajan was minimised with periodic spray of contact insecticides. The varying level of biotic stress i.e., No, Low, Medium, and High level was maintained on C. cajan plants with lac insects on it. The three levels of abiotic stress in this experiment were considered in terms of soil moisture stress. It was managed through irrigation per plant through drip system, it was considered that creating different levels of moisture stress in soil will impact the host plant. The abiotic stress was of three levels i.e., Low, Medium, and High. The result reveals that survival percent of Lac insect from brood lac inoculation to the harvest of lac crop was highest 37.52 percent on C. cajan with one primary branch and its secondary branches with lac insect (L1- Low biotic stress). It was 32.13 percent (W3- Low soil moisture stress). The study indicates that biotic and abiotic stress play a major role in the survival of K. lacca.

Genotype×Environment Interaction and Stability Analysis Using GGE Biplot for Grain Yield of Bread Wheat (Triticum aestivum) Genotypes under Low Moisture Stress Areas of Ethiopia

A multi-location Experiment was conducted using 28 genotypes and two checks during the main cropping seasons of 2017 and 2018 at Kulumsa, Dhera, Melkasa, Asasa, Ilala, and Geregera in moisture-stress areas of Ethiopia to evaluate the genotype-Environment interaction effect and grain yield stability of bread wheat genotypes. The experiment was arranged in alpha lattice design replicated three times. The stability analysis was carried out for grain yield using R software. ANOVA showed a highly significant difference among genotypes and genotype×environmental interaction for traits; days to heading, days to maturity, plant height, grain yield, 1000 kernel weight. The average mean yield of the genotypes across the environments was 4.5 with the range of 3.5–5.3 t ha-1. The genotypes ETBW 9578, ETBW 9565, ETBW 9570 and ETBW 9571 were top-yielding, ideal, and stable across the ten environments. However ETBW 9589 and Ogolcho were the low-yielding genotypes. The “which-won-where” graph categorizes the genotypes into four groups. The locations within the same group were closely correlated and share the same winning(vertex) genotype. E7 was ideal that has both discriminating abilities of the genotypes and representative of the other test environments. ETBW 9578 gave 37.7% and 39.1% yield advantage over the standard check Kingbird and local check Ogolcho, respectively. As a result the genotype ETBW 9578 was released in 2020 and designated by the variety name “Dursa”. Thus, it was concluded that the Dursa variety could be used as a stable variety for cultivation.

Cluster and principal component analysis of maize inbred lines in low moisture stress areas in Ethiopia

This study used to cluster and principal component analysis to assess the agronomic and physiological variability of 40 maize inbred lines under low moisture stress conditions in Ethiopia. The study was conducted at Melkassa locations during the 2017 main season. The analysis of variance showed the mean square due to genotype was highly significant (p < 0.01) for all traits which indicates the existence of sufficient genetic variability and potential for selection and improvement on the characters. Cluster analysis revealed four distinct groups of inbred lines, The members of clusters 1 and 4 may be combined in future breeding programs to obtain genotypes/hybrids that can perform well under drought stress conditions. The inter-cluster D2 values varied from 48.65 to 4407 indicating the high range of diversity present among the genotypes. while principal component analysis showed the first six PCs having Eigen value >1 explaining principal components that accounted for 77.7% of the total variation among the inbred lines. The first three principal components PC1, PC2, and PC3 with values of 25.25%, 18.03, and 11.7% respectively more contributed. Grain yield, plant height, ear height, and the number of leaves per plant were the most important traits influencing the variability among the inbred lines.

Comparative Study of Wheat (Triticum aestivum L.) Genotypes in Irrigated and Rainfed Conditions

Wheat is 3rd major cereal crop of Nepal in terms of production and productivity, however, in a significant area wheat is still grown under rainfed conditions. There are very less wheat varieties particularly released for rainfed environments, indicating a very poor varietal choice for the farmers. This study aims to compare the performance of selected wheat genotypes under irrigated and rainfed conditions of the western terai region of Nepal to identify suitable genotypes for low moisture stress conditions. The experiment was conducted comprising 24 wheat genotypes including check varieties (Gautam, RR21, and Bhrikuti) in Alpha Lattice design with two replications at the Directorate of Agricultural Research, Lumbini Province, Khajura, Banke in 2021/22. The set of genotypes was evaluated simultaneously under rainfed and irrigated environments in an open field condition. In a rainfed environment, NL 1446 produced the maximum grain yield of 3488 kg ha-1, followed by NL 1437 (3357 kg ha-1). The highest grain yield under irrigation was obtained from NL 1503, which produced 4273 kg ha-1, followed by NL 1437 (4242 kg ha-1). Regarding grain yield, NL 1437 was observed to be a better genotype under both circumstances. NL 1437 produced an average grain yield of 3799 kg ha-1 after integrated analysis. According to the study, NL 1503 is the best genotype to be used, provided timely irrigation is guaranteed; otherwise, NL 1446 and NL 1437 are the best alternatives. NL 1437 gave the highest mean grain yield in both rainfed and irrigated conditions, thus having greater potential for cultivation in water-stress environments. Likewise, the results from the study can be helpful in breeding programs and facilitate the development of drought-tolerant wheat varieties.

Fire interval and post-fire climate effects on serotinous forest resilience

BackgroundClimate change is eroding forest resilience to disturbance directly through warming climate and indirectly through increasing disturbance activity. Forests characterized by stand-replacing fire regimes and dominated by serotinous species are at risk when the inter-fire period is insufficient for canopy seed bank development and climate conditions for recruitment in the post-fire growing season are unsuitable. Although both factors are critical to serotinous forest persistence, their relative importance for post-fire regeneration in serotinous forests remains poorly understood. To assess the relative effects of each factor, we established plots in severely burned knobcone pine (Pinus attenuata Lemmon) forests in Oregon and California, USA, representing a range of past fire intervals (6 to 31+ years). Specifically, we evaluated effects of fire interval and pre-fire canopy seed bank (proxies for seed supply) and post-fire climate on three metrics of post-fire tree regeneration (seedling density, probability of self-replacement, percent population recovery).ResultsSeed supply consistently had the strongest effect on post-fire regeneration. Between 6- and 31-year fire intervals, post-fire seedling density increased from 1000 to 100,000 seedlings ha−1, while probability of self-replacement increased from ~ 0 to ~ 100% and percent population recovery increased from 20 to 2000% of the pre-fire population, respectively. Similarly, increasing the canopy seed bank by two orders of magnitude increased seedling density and percent population recovery by two orders and one order of magnitude, respectively, and increased the probability of self-replacement by > 50%. Greater post-fire climatic moisture deficit exacerbated the effect of seed supply; an additional 4–6 years between fires was required under high moisture stress conditions to reach similar regeneration levels as under low moisture stress conditions.ConclusionThe overriding effect of seed supply—strongly driven by pre-fire stand age—on post-fire regeneration suggests that altered fire frequency (an indirect effect of climate change) will have a profound impact on serotinous forests. Although direct effects of hot and dry climate are lower in magnitude, they can alter forest recovery where seed supply nears a threshold. These findings reveal how fire interval and climate combine to determine changes in forest cover in the future, informing management and vulnerability mapping.

Comparing the Effects of Different Organic Mulching Materials on Weed Control, Soil Moisture Conservation, and Wheat (Triticum Aestivum) Productivity in the Moisture Deficit Areas

Wheat (Triticum aestivum) productivity, in water deficit areas such as Ethiopia, is threatened by low soil fertility, weed infestation and moisture stress. Organic Mulch was believed to avert these challenges but only limited scientific information, on its level of effects (crop yield, soil moisture conservation and weed control), was available. Hence, an experiment was carried out on Cambisols in Tigray/Ethiopia during the 2019/20 growing season following a Randomized Complete Block Design (RCBD). Four organic mulch types (maize stalk, sorghum stalk, wheat straw, and finger millet straw), each at the rates of 2 ton ha-1 were compared against the control (no mulch). Their economic visibility was evaluated using partial budget analysis. Our experimental results revealed that mulched plots had a significantly higher weed control efficiency, soil moisture content, grain yield, and net benefit as compared to the control. Mulching in general improved Wheat grain yield by 26.8%, soil moisture (at 0 – 20 cm) by 73.7%, weed control efficiency by 57.4%, and net benefit by 19.7% as compared to the control. Maize and sorghum stover mulches were the most profitable mulch types which increased net benefit by 38.2 and 27.6%, respectively. It can be concluded that organic mulching with Maize and Sorghum stover is a good option to improve crop production, soil moisture and reduce weed infestation in the moisture deficit areas.

Differentiating grazing-induced rangeland grass nutrition status in situ using near infrared reflectance

Assessing the nutrient content of rangeland grass using earth observation technologies presents opportunities for non-destructive, rapid and repetitive appraisals in support of rangeland management. The biochemical-related concentrations of macronutrients (N, P, K, Ca, Mg) are among the factors that influence near infrared reflectance (ρNIR) by a turgid leaf. High grazing intensity (GI) enhances nutrient recycling in rangelands, resulting in high concentrations in aboveground grass tissue. This study sought to establish whether grazing-induced macronutrient abundance in rangeland grass can be remotely sensed in situ through ρNIR in the multiple species natural settings. Sampling was conducted at peak grass growth stage in large savannah rangelands with similar grass species mixtures, in low moisture stress conditions. The sampling was widely distributed in GI-contrasted livestock and wild grazer rangelands, and in grazing-restricted control sites. Two species representing high and low nutrient grass species, respectively, were sampled. At each sampling site (N = 116), reflectance was measured in the 350–2500 nm range from leaf and stem tissue of healthy-looking specimens of the two species (≤10 m apart), using a 1.1 nm – 1.4 nm resolution spectroradiometer. Macronutrient concentrations (MNC) in the tissue were then determined in the laboratory. For each species, the hyperspectral NIR (λ700 – 1100 nm) reflectance was averaged per sampling site. Individual and total MNC, respectively, were correlated with the hyperspectral ρNIR, and then with atmospheric effect-corrected ρNIR from 10 m-resolution, field sampling-concurrent Sentinel-2 MSI multispectral images. For each sampling site, the two species’ hyperspectral ρNIR values, individual and total MNC, respectively, were then averaged. Respective models relating the paired hyperspectral ρNIR and averaged MNC were developed, by linear regression and partial least squares regression (PLSR). Tissue MNC were lowest in the control sites and higher in the grazed rangelands. Covariance in MNC in the two species suggested location-context similarities in all grasses. Individual and total MNC, respectively, had statistically significant (p < 0.01) negative correlations with both tissue level hyperspectral and multispectral ρNIR. The negative relationship was detected on empirical line-retrieved ρNIR on historical Hyperion hyperspectral images. PLSR yielded a more accurate predictive model (R2 = 0.760) than linear regression (R2 = 0.601, F = 138.415, p < 0.0001). The study shows that there are possibilities to remotely sense grazing-induced MNC in aboveground grass tissue through changes in ρNIR.

Breeding Drought Tolerant Cotton; With an Emphasis on Within Boll Yield Components

Evolution of low moisture stress tolerant genotypes of cotton is a dire need of the time for sustainable/increased production of cotton in Pakistan. A study was conducted to estimate the varietal differences and genetic control of various within boll yield components and fiber quality traits under normal and moisture stress conditions. Five parents viz; PB-39, MNH-886, MNH-147, CIM-598, BH-95 and their ten direct crosses were grown in field in split plot arrangement under randomized complete block design with two replications. Analysis of variance revealed significant differences between the two treatments (normal and moisture deficit) and among the fifteen genotypes for all the recorded traits including bolls number per plant, weight per boll, seed cotton yield per plant, GOT, seeds number per boll, seeds mass per boll, lint mass per boll, fiber length, fiber strength and fiber fineness. Treatment × genotype interaction was also significant for all the traits except fiber fineness. Variance due to GCA and SCA were significant for most of the traits; however magnitude of dominance variance was higher than additive variance indicating prevalence of non-additive genetic control for all the traits under both the conditions. The phenotypic expression of all the genotypes varied greatly under the two growing conditions.

Restoration of rainwater techniques and fertilizer split application methods on yield and total nutrient uptake of rainfed sorghum under vertisols (Typic haplusterts)

In rainfed situation soil erosion, low plant nutrients availability and soil moisture stress during cropping season are among the major limitations to high crop production and sustainable land management in a rainfed Semi-Arid Tropics (SAT) in India. A field experiment was conducted to study the effect of land configuration practices and fertilizer split application methods under vertisols condition in Rabi sorghum. The results revealed that the in-situ soil moisture conservation practices viz., broad bed furrow registered the highest yield attributes, yield, soil fertility status and plant nutrient uptake in rainfed sorghum. Under vertisols rainfed condition soil moisture conservation methods viz., broad bed furrow recorded higher yield (1611 kg/ha), net income (Rs.6675/ha), BC ratio (1.37) and RWUE (4.49 kg/hamm). But in case of fertilizer treatments, the treatment applied with 20 kg N as urea + 20 kg P2O5 enriched with farm yard manure + 10 kg K2O/ha as basal application and top dressing as 20kg N as urea and 10kg K kg/ha registered higher yield attributes, grain yield (1734 kg/ha), stalk yield (4357 kg/ha), net income (Rs.10607), BC ratio (1.70) and RWUE (4.81 kg/hamm) and plant nutrient uptake viz., nitrogen uptake (67.82 kg/ha), phosphorus uptake (19.30 kg/ ha), potassium uptake (108.06 kg/ha) and zinc uptake (117.1), respectively.

Seed germination ecology of leucaena (Leucaena leucocephala) as influenced by various environmental parameters

AbstractLeucaena [Leucaena leucocephala (Lam.) de Wit] is a perennial weed in more than 25 countries, including Australia. Knowledge regarding the seed biology of L. leucocephala could help in making weed management decisions. Experiments were conducted to study the effect of hot water (scarification), alternating temperatures, heat stress, salt stress, water stress, and burial depth on seed germination of two populations of L. leucocephala collected from Toowoomba and Gatton, Australia. The optimum duration of hot water treatment to break the hard seed coat dormancy was 2 min for both populations. The highest germination (92% to 98%) was recorded at 35/25 C for both populations, and similar germination occurred at 30/20 C. The Toowoomba population recorded greater germination at low temperature (15/5 to 25/15 C) than the Gatton population. Additionally, the Gatton population had higher germination than the Toowoomba population after 5 min of exposure to temperatures of up to 100 C, suggesting that the Gatton population may be more tolerant to heat stress. Germination was completely inhibited at pretreatment (5 min) temperatures of 150 to 250 C. The Toowoomba population recorded 17% greater germination than the Gatton population at a high salt concentration (160 mM NaCl), indicating its greater salt tolerance. At low moisture stress (−0.1 and −0.2 MPa), higher germination was observed in the Toowoomba population than in the Gatton population, whereas germination was similar for both populations at higher water stress levels (−0.4 MPa or lower). Germination was similar for both populations at shallow depths (0 and 1 cm) but higher emergence was recorded for the Toowoomba population at 2 to 8 cm than the Gatton population. Differential germination behaviors of both populations suggest that they adapted differently in their respective local environments. Knowledge gained from this study will help in formulating integrated management practices for L. leucocephala.

Soil fertility and water availability effects on trait dispersion and phylogenetic relatedness of tropical terrestrial ferns.

Analysis of plant functional traits and their phylogenetic relationships has shed light on the processes structuring the occurrence patterns of angiosperm taxa across environmental gradients. In montane tropical forests, angiosperms coexist with diverse communities of terrestrial ferns, with distinct evolutionary histories, leaf morphology, and reproductive systems. Here we examined the functional traits, functional dispersion, and phylogenetic diversity of ferns across a well-described gradient of moisture and soil nutrient availability in a premontane tropical rainforest in western Panama. We measured 15 functional traits from 33 terrestrial fern species occurring in 12 one-ha plots. We applied RLQ and fourth-corner analyses to assess relationships between trait and environmental variables and used beta regression to evaluate how functional dispersion responds to environmental factors. In addition, we analyzed trait distributions with respect to fern phylogeny. We found that functional composition was predicted by soil variables and dry season rainfall. Leaf phosphorus (P) increased and leaf carbon (C) to nitrogen (N) ratio decreased with increasing soil total N:P ratio. Functional dispersion decreased with increasing soil total N:P in wet sites and with increasing manganese in dry sites, suggesting that low soil fertility and dry season moisture stress both tend to reduce functional diversity. Traits exhibited phylogenetic clustering primarily at deep nodes associated with tree versus herbaceous fern clades. Our results indicate that environmental filtering of functional traits affects ferns in a similar way to angiosperms and highlight the association of the early tree fern clade with low fertility soils.

Application of Potassium along with Nitrogen under Varied Moisture Regimes Improves Performance and Nitrogen-Use Efficiency of High- and Low-Potassium Efficiency Cotton Cultivars

Low nitrogen-use efficiency (NUE) is a serious issue for cotton production and environmental sustainability in arid climates. A pot study was conducted to evaluate the effect of K nutrition on NUE and performance of low- and high-K-efficiency cotton cultivars under two moisture regimes. Treatments included two soil moisture levels—i.e., normal irrigation, 100% available water content (AWC); reduced irrigation, 50% AWC—three levels of nitrogen (N)—i.e., 0, 375, and 750 mg N pot−1—and two K levels, i.e., 0 and 208 mg K pot−1. Results reveal that 208 mg K pot−1 application with nitrogen significantly enhanced the N-use efficiency, growth, and yield attributes of both cotton cultivars compared with sole N fertilization. Similarly, the combined application of NK @ 375 N + 208 K mg pot−1 caused up to 83% increase in NUE under AWC50% and AWC100%, as compared with NK control (0 N + 0 K). Compared with the control, imposed low-moisture stress caused a decrease of 13.9% in stomatal conductance (gs), 2.5% in transpiration rate (E), and 6.5% in net photosynthetic rate (PN), respectively. The physiological water use efficiency (PN/E) decreased by 13.2% under AWC50%. Applied NK @ 375 N:208 K, mg pot−1 caused 27.39 and 27.56% improvement in the PN/E in HKE and LKE cultivars under AWC50%, respectively. The HKE cultivar, i.e., CIM-554, maintained the highest gs and PN than FH-901, that was low-K-efficiency cultivar. The study suggests that varietal selection and adequate K fertilization have the prospects to improve NUE and save considerable quantities of fertilizer and irrigation water in cotton production under arid environments.

General and Specific Combining Ability of Quality Protein Maize (Zea mays L.) Inbred Lines for Major Foliar Diseases, Grain Yield and Other Agronomic Traits Evaluated at Mid-altitude Agroecology of Ethiopia

Abstract: Despite the fact that maize is a crucial cereal crop for food security, several foliar diseases are the main threats and limitations maize production in Ethiopia, resulting in low yields, particularly quality protein maize (QPM). Accordingly, national maize research program of Ethiopia has released QPM maize varieties adapted to the mid-altitude, low moisture stress and highland agro-ecologies of the country. Nonetheless, the market share of these varieties is generally small due to these reason and other features that have limited their adoption by farmers. General and specific combining ability analysis is one of the powerful instruments in identifying the best combiners that may be used in crosses to accumulate biotic resistance and productive alleles. A line x tester analysis involving 36 crosses generated by crossing 9 selected maize inbred lines with 4 testers were evaluated for different desirable agronomic traits during 2019/2020 main season at Bako and Jimma. The purpose of the experiment were to determine the GCA and SCA combining ability of QPM inbred lines, adapted to mid altitude agroecology of Ethiopia for grain yield and major foliar diseases. The crosses were evaluated in alpha lattice design replicated 3 times. For analysis of days to silking interval, days to maturity, turcicum leaf blight, grey leaf spot, common rust disease severity index, and grain yield were recorded. Analyses of variances showed significant mean squares due to crosses for almost all the traits studied. GCA mean squares due to lines and testers were significant (P&lt;0.05 or P&lt;0.01) for most studied traits. SCA mean squares were also significant for most attributes and major foliar maize diseases across locations. The comparative importance of GCA and SCA variances observed in the current study for most studied traits. Inbred lines L1, L2, L5 and L8 exhibited negative and highly significant GCA effects for husk cover. From this conduct it can be decided that better performing hybrids, inbred lines with desirable GCA and cross combinations with desirable SCA effects for grain yield, major foliar maize diseases and other traits were successfully identified.