Variation In Fertility Research Articles

CONE YIELD AND GROWTH CHARACTERISTICS IN A PLANTATION OF CUPRESSUS SEMPERVIRENS

Mediterranean cypress (Cupressus sempervirens L.) is an important secondary forest tree species in Turkish forestry because of its high adaptation ability and resistance to different ecological condition. However, limited studies were carried out in cypress. In this study, cone numbers, tree height, diameters at breast height and at base were surveyed from 75 individuals chosen randomly at eighteen years’ plantation in the species. Interaction between number of cones and growth characteristics was estimated together with fertility variation and linkage parameters (i.e. population size) to contribute management and practices of seed collection and gene conservation areas, and other forestry practices of the species. Mean cone number was 86/tree ranged from 36 to 174. Individual trees had large differences for the growth traits, while means of tree height, diameters of breast height and base were 6.1 m, 9.9 cm, and 12.6 cm, respectively. Fertility variation was 1.15 (87% of total trees, CV%=38.9), which close to typical population. Positive and significant (p≤0.05) relations were found between growth characteristics and cone production in Cupressus sempervirens. Tree height was better predictor in cone production than diameters.

Effects of cypermethrin on morphological, physiological and biochemical attributes of Cicer arietinum (Fabales: Fabaceae)

Cypermethrin, a synthetic pyrethroid, is a widely employed pesticide in large-scale commercial agriculture and domestic settings to control pests and boost crop yields. Despite its effectiveness in controlling pests, concerns persist about the potential ecological and human health impacts associated with its use. In the present study, the impact of cypermethrin on different parameters, including growth indices, pollen morphology and pollen fertility, chlorophyll and carotenoid content, hydrogen peroxide (H2O2) scavenging, lipid peroxidation (MDA concentration), superoxide dismutase (SOD), and catalase (CAT) activities, was investigated in Cicer arietinum L. The results showed that plants exhibited decreasing trends in plant height, number of branches, pods, and seeds per plant as cypermethrin concentrations increased. These changes resulted in significant reductions in the overall yield of the plants. The percentage of wrinkled pollen significantly increased with higher concentrations of cypermethrin and longer exposure durations. Exposure to cypermethrin showed significant variations in pollen fertility of C. arietinum at different concentrations and time intervals in comparison to control, which had a baseline pollen fertility of 79.12% ± 4.59. Chlorophyll and carotenoid content of C. arietinum were considerably affected by cypermethrin, indicative of potential disturbances in essential photosynthetic processes crucial for plant health. Further, with increasing concentrations of cypermethrin ranging from 100 mg/L to 500 mg/L, noticeable effects were observed on H2O2− scavenging, MDA concentration, SOD and CAT activities of C. arietinum in dose-dependent manner. Further, it was found that the duration of exposure and concentration of cypermethrin played a crucial role in exacerbating these detrimental effects. The findings of the present study raise concerns regarding the harmful effects of agricultural pesticides like cypermethrin and highlight the need for more research on the nutritional value of products derived from plants and seeds exposed to these agents.

A novel on-line dual sensing system for soil property measurement and mapping

Real-time assessment of within-field soil fertility variation is crucial for making informed and sustainable decisions, like crop nitrogen (N) fertilization. Two commonly used soil sensors i.e., visible-near-infrared (vis-NIR) spectroscopy and ion-selective electrodes (ISE) have been reported to successfully estimate various soil macronutrients and nitrate-N, respectively, however, their integrated use for mapping a full-scale soil fertility variation has not been taken into consideration to date. The aim of this study is to use an integrated on-line dual-sensor system of vis-NIRS and ISE to estimate and map within-field variation in multiple soil fertility parameters including pH, organic carbon (OC), extractable- phosphorus (P), potassium (K), calcium (Ca) and moisture content (MC) and nitrate-N. The sensing system was mounted to the three-point linkage of a tractor and surveyed two arable fields in Belgium. Partial least squares regression models for vis-NIRS sensor were calibrated and validated, while a linear regression model was established for validation of the ISE sensor. Geostatistical surface maps for on-line measured soil attributes were generated using the inverse distance weighting and ordinary kriging methods for ISE data and vis NIR, respectively. The linear correlation confirms a very high similarity between ISE-measured nitrate-N and laboratory-analyzed nitrate-N (coefficient of determination (R2) = 0.93). Besides, the vis-NIRS demonstrates very good prediction accuracies for all the fertility attributes with R2 = 0.70-0.78, root mean square error (RMSE) =0.52-2.46 %, residual of prediction deviation (RPD) = 1.89 – 2.13 and the ratio of the performance to interquartile distance (RPIQ) = 1.72 – 6.56. Validation between laboratory and on-line measured soil maps also shows quite comparable spatial distribution patterns. Therefore, the proposed dual on-line sensor system has a high potential to estimate and map within-field spatial fertility distributions including nitrate-N, offering a basis for sustainable management decisions for precision soil and crop production.

Intergenerational transmission of fertility: evidence from China's population control policies

Abstract This paper examines how the number of siblings that parents have affects their fertility decisions in China. The population control policies in China affected individuals unequally across birth cohorts and regions. The exogenous variation in fertility is used to identify the effect of the number of siblings on the number of children for the next generation. The results show that a couple tends to have 0.034–0.068 more children (2.3–4.6% of the average number of children) and is 2.4–6.8 percentage points more likely to violate the One-Child Policy (9.3–27.1% of the violation rate) if the husband and the wife have one more sibling each. Moreover, the effect on fertility is stronger for couples in lower-income provinces where the fertility rate is higher and in rural areas where the One-Child Policy was enforced less strictly. Finally, I show that the ideal family size of the husband and wife is an important channel through which the number of siblings affects fertility. I also find that the effect of people's number of siblings has a larger effect on their ideal number of children than on their actual number of children, suggesting that they are constrained from achieving their fertility ideals.

Glacial interglacial variations in the natural iron fertilization during the low sea ice periods along the eastern continental margin of Antarctica

The Southern Ocean sequesters atmospheric CO2 through biological pumps, though its driving factors are debated. Modern productivity is regulated by natural iron fertilization from micronutrient influx through dust, regeneration, and Antarctic glaciers and sea ice melting (ice melt). The productivity along the eastern Antarctic continental margin was low during the last glacial period and gradually increased through the deglacial to Late Holocene, marked by distinct productivity peaks. The micronutrients also varied similarly, with reduced glacial influx and an increase in the Holocene, which may cause productivity peaks. Therefore, the coherence of enhanced productivity and micronutrient influx is considered as enhanced iron fertilization period. The productivity peaks declined within ∼1.5 kyr, mostly due to the Ekman transport and sea ice formation. Along with ice melt, the independent weathering pattern that responds with glacial- interglacial ice volume changes suggest the source of micronutrients is not terrigenous. Shelf interaction of oceanic currents can influence the water column nutrient stock significantly, while its utilization occurs during reduced ice periods (low sea ice and high glacier melting) for productivity. Therefore, enhanced natural iron fertilization periods are considered as ice low periods that occurred in a periodicity of 2 kyrs, at ∼7.5 kyr BP, ∼5.5 kyr BP, ∼4 kyr BP, ∼ 2.5 kyr BP, and ∼0.5 kyr BP, likely due to the combined effects of atmospheric and oceanographic factors driven by the high amplitude regional temperature variability during the mid to late Holocene.

Calibrated SoilOptix ® estimates of soil pH and exchangeable cations in three agricultural fields in western Canada – implications for managing spatially variable soil acidity

Spatial variability in soil pH is a major contributor to within-field variations in soil fertility and crop productivity. An improved understanding of the spatial variability of soil pH within agricultural fields is required to determine liming requirements for precision farming. This study with the use of proximal sensors, firstly assessed the spatial pattern of soil pH and how it can be used to determine site-specific, spatially variable lime requirements. Secondly, the effects of soil pH on soil concentrations of nitrate nitrogen (N03-N), phosphorus (P), potassium (K), sulfur (SO4-S), calcium (Ca), magnesium (Mg), soil organic matter (SOM), aluminum (Al), and manganese (Mn) were assessed in three study fields in central Alberta, Canada. Soil pH varied between 4.5 and 7.5 across all field sites. The field-scale coefficient of variation (CV %) for soil pH, Al and Mn ranged between 4.39 and 7.50 %, 7.33–13.72 %, and 7.33–13.72 % across the three sites. The other soil properties showed low, moderate, and high variability, with field-scale CVs ranging between 6.39 and 17.70 % for SOM and 24.33–91.39 % for SO4-S. Soil pH exhibited positive correlations with both Ca and Mg, across all fields. Negative correlations were observed between soil pH and Al across all fields. A principal component analysis (PCA) was performed for all soil parameters and two principal components accounted for 50 %, 54.9 %, and 76.8 % of the total variance in field 1, field 2, and field 3, respectively. Geostatistical semivariance indicated a strong spatial dependence of all chemical parameters across fields. Large regions within a field were strongly acidic (pH < 5.5) and required lime applications ranging from 0 to 6 t ha−1. We conclude that proximal soil sensors can be calibrated to soil properties, enabling variable rate lime recommendations on spatially variable fields for the management of soil acidity.

Spatial distribution and factors associated with high completed fertility among women aged 40–49 years in Ghana: evidence from the 2022 Ghana Demographic Health Survey

BackgroundHigh completed fertility among married and cohabiting women has profound consequences, including straining resources, increasing healthcare challenges, and contributing to educational and gender inequalities. This study examined the factors associated with high completed fertility among married and cohabiting women aged 40–49 years in Ghana.MethodsData for the study was sourced from the 2022 Ghana Demographic and Health Survey (GDHS). A spatial map was used to present the women's geographic variations in high completed fertility. A mixed-effect multilevel binary logistic regression analysis was performed to identify the factors associated with high completed fertility. The findings were presented as adjusted odds ratios (aOR) with a 95% confidence interval (CI).ResultsThe national proportion of high completed fertility among married and cohabiting women aged 40–49 years in Ghana was 52.0% [48.8, 55.2]. Women who were Ga/Dangme/Ewe by tribe [aOR = 2.32, 95% CI = 1.06, 5.08] had higher odds of high completed fertility than Akans. Women who indicated 6 + as their ideal number of children had a higher [aOR = 5.60, 95% CI = 2.90, 10.82] likelihood of high completed fertility compared to those whose ideal number of children was 0–3. Those who were using contraceptives at the time of the survey had a higher [aOR = 2.31, 95% CI = 1.17, 4.55] likelihood of high completed fertility compared to those who were not using contraceptives. Women with secondary/higher education [aOR = 0.32, 95% CI = 0.17, 0.58] had lower odds of high completed fertility than those without no formal education. Women with females as household heads [aOR = 0.56, 95% CI = 0.33, 0.95] had lower odds of high completed fertility than males. Women in Volta, Western North, Ahafo, and Bono regions had lower odds of high completed fertility compared to those living in the Northeast region, with the lowest odds among those living in the Volta region [aOR = 0.08, 95% CI = 0.02, 0.40].ConclusionHigh completed fertility is prevalent in Ghana, with more than half of married and cohabiting women having at least five or more children. The government and policymakers in Ghana should promote education for women, increase culturally sensitive family planning programs, increase access to family planning resources, address ideal family size preferences, and improve understanding of contraceptive use.

Ethnic specifics in birth rates in Kazakhstan in the middle of the 20th century

The purpose of this study is to examine ethnic variations in population fertility in the 1950–1960s, formed in the context of socio-economic development of Kazakhstan. The 1959, 1970, 1989 population censuses, and sta-tistical almanacks “National Economy of Kazakhstan” became the source base of this research. The theory of modernization, interpreted as the transition from traditional to modern society and reflecting the details of ethni-cally differentiated process of demographic development of Kazakhstan in the mid-20th century provided the methodological basis of the research. Ethnic differentiation within the settlement system and socio-economic ac-tivities that developed in Kazakhstan in the 1950–1960s led to ethnically distinct birth rates among Kazakhs and Russians. The demographic potential acquired by Kazakhs in the middle of the 20th century became the demo-graphic basis of sovereign Kazakhstan.

Flower Yield, Physiology, Nutrient Acquisition and Soil Fertility Variations in Cut Flower Rose (Rosa hybrida L.) as Influenced by Rootstocks

Flower Yield, Physiology, Nutrient Acquisition and Soil Fertility Variations in Cut Flower Rose (Rosa hybrida L.) as Influenced by Rootstocks

Fertility Variations among Ethnic Groups in South Africa

Fertility Variations among Ethnic Groups in South Africa

Bibliometric Analysis of Trends and Future Directions of Research and Development of Seed Orchards

Seed orchards are important seed resources for producing improved tree crops for future plantations, forest restoration, and forestry practices (i.e., gene conservation) and for transmitting current gene diversity to future generations. Seed orchards are a major sub-division in forest science. The establishment and management of a seed orchard involves many steps, from the selection of superior trees to the harvesting of a seed crop. Studying the trends and future directions of seed orchards using different analysis methods is critically important, especially to establish resistant forests via the production of climate-smart, biotic/abiotic-stress-resistant seedling materials. Published papers related to seed orchards should be analyzed to determine the current trends in this field and to contribute to its future directions. Bibliometric analysis has been used for different purposes in various scientific fields. However, it has not been performed for publications in seed orchards. This study was carried out to analyze the current trends of research on seed orchards and to determine the future directions of these orchards based on published papers. For these purposes, 1018 published papers were obtained from the Science Citation Index, Science Citation Index Expanded, and citation index databases of “Web of Science” using the keyword “seed orchard”. The papers were published between 1980 and 2022 and were subjected to bibliometric analysis based on the most prolific contributors, references, countries, and keywords. CiteSpace software 6.1 R6 was applied to visualize information about seed orchard research. The average number of citations per publication was 13.05, and the 4 H-Index of the publication set was 48. The most prolific contributors with the strongest citation bursts, the highest centrality, and the greatest numbers of published papers were from Canada, Sweden, South Korea, Finland, and Czech Republic, while Canada (186 published articles), the USA (140), and Sweden (115), together with China, Brazil, and Germany, were active countries, especially based on citations from recent years. The “keywords” of the papers were the core of the research. “Mating pattern”, “Swedish forestry”, “fertility variation”, “Hymenoscyphus fraxineus”, “threatened Pacific sandalwood”, “outbreeding depression”, “climate change”, “management”, and “growth”, together with others such as “genetic improvement” and “effective size”, were active study areas and keywords, based on results of the analysis. They also guided the literature search and inventory and classification of early studies and served as predictors for future studies. The results of this study are discussed based on the trends and future directions of the research and development of seed orchards.

A Comparative Study of Fertilizer Prices Purchased by Farmers from Rythu Bharosa Kendras (RBKs) and Other Agencies in Andhra Pradesh

Rythu Bharosa Kendras - a one stop solutions for all agriculture &amp; allied issues, was launched by state government of Andhra Pradesh in 2020. It addresses various issues and provide services to the farmers at the village level. Fertilizers are one among the services offered at Rythu Bharosa Kendras. The current study was carried out during the year 2022 and 2023 to find any significant variation in the average price of the fertilizers purchased by the farmers from Rythu Bharosa Kendras versus other agencies in Tirupati and Chittoor districts of Andhra Pradesh. A representative sample of 120 farmers in two districts of Andhra Pradesh i.e., Tirupati and Chittoor were selected for the study. Through a pre-structed interview schedule, prices of fertilizers purchased by the farmers from Rythu Bharosa Kendras vs other agencies were collected. In the study area, other agencies from where farmers purchased fertilizers included private fertilizer wholesalers, retailers, fellow farmers, non-institutional financers, etc. To study the average price comparison, the set of fertilizers that were commonly purchased at Rythu Bharosa Kendras and other agencies were selected. They were Urea, Diammonium phosphate (DAP), Muriate of Potash (MOP), N20:P20:K0:S13 (N:P:K:S fertilizer grade), N10:P26:K26 (N:P:K fertilizer grade). From the data collected and through descriptive statistical analysis it was clear that for all the common fertilizers the average amount of fertilizer per bag at Rythu Bharosa Kendras was comparatively lower than that of fertilizers purchased at other agencies. The average price variation of fertilizer per bag at Rythu Bharosa Kendras to other agencies for Urea, DAP, MOP, N20:P20:K0:S13 grade, N10:P26:K26 grade were Rs. 27.5, Rs. 40, Rs. 33, Rs. 44 &amp; Rs. 92 with a variation in percentage by 10.3%, 2.96%, 2.84%, 3.26% &amp; 6.31% respectively. By ensuring the prompt availability of required set of fertilizers in line with the cropping pattern of the farmers and by streamlining the supply chain aspects of fertilizes, especially from fertilizers hub to Rythu Bharosa Kendras, will be beneficial &amp; results in cost optimization to the farmers.

EFFECT OF FUNCTIONAL STRATEGIES AND ABUNDANCE OF Acacia mangium Willd ON THE NUMBER OF NATIVE SPECIES IN A SECONDARY FOREST FRAGMENT IN SOUTHERN AMAPA, BRAZIL

Acacia mangium Willd is a fast-growing exotic tree that, when inserted in a different environment, can present an invasive potential in secondary forests. This study aimed to analyze the effect of abundance and functional strategies of A. mangium Willd and edaphic factors on native species richness in a secondary forest fragment located behind the Instituto Federal do Amapá campus Laranjal do Jari, Amapá. For this, all tree individuals with diameter at breast height (DBH) ≥ 10 cm occurring in 10&#x0D; plots of 200 m2 distributed in the fragment were identified. Soil samples were collected in the plots and sent for fertility and granulometry analysis. Three leaf functional attributes of individuals of A. mangium Willd occurring in the plots were measured: leaf area (LA), leaf thickness (LT) and specific leaf area (SLA). A total of 145 tree individuals and 14 species were sampled, with A. mangium Willd being the most abundant with 95 individuals. The relative abundance of A. mangium Willd was negatively related to native species richness in the fragment. The species also exhibited distinct leaf attributes and abundances according to the variation in soil acidity and fertility in the fragment, which influenced the number of native species. There is a need to develop monitoring and management of invasive exotic species such as A. mangium Willd in fragments of secondary forests, since the species is invasive and opportunistic, and can inhibit the regeneration of native species after local disturbances.

Fertility and long‐term economic growth

AbstractEmpirical studies have generally found that higher fertility has a negative or insignificant effect on economic growth. This article argues that this is because existing studies have failed to capture the long‐term lagged effects of fertility. By estimating a long‐term lagged panel model using data from 137 countries, I find that higher fertility first reduces and then increases economic growth, and the long‐term average effect is significantly positive. This finding is robust when focusing on countries at different development levels, exploiting exogenous fertility shocks from global family planning campaigns, and capitalizing on within‐country fertility variation resulting from China's one‐child policy.

Study on Soil Fertility Variations, Distribution of Soil Health Report and Key Suggestions for Problems Identified for Improvement of Livelihoods in Adopted Village Narsimhulapalle, Telangana, India

The Agricultural College, Sircilla of Professor Jayashankar Telangana State Agricultural University, as the sixth and youngest college of the University, started during the academic year 2018-19. One of the mandatory activities of the college in addition to academics is adoption of village and disseminating need based relevant technologies of the University for improvement of livelihoods of the villagers. Hence, a village by name Narsimhulapalle of Thangallapalli Mandal, Rajanna Sircilla district was adopted as part of extension activities of the college which is about 19 km from the college. Prior to the dissemination of improved technologies, the identification of existing scenario in the village with regards to soils, fertility status, crops, varieties, package of production technologies followed were taken up. Soil samples were collected with geo-positions from every farmer’s field i.e., 114 farm holds of the village, processed and tested for fertility status. Action plan was prepared based on crop grown to alleviate the livelihoods of the village. A systematic collection of demographic, socio economic conditions and livelihoods of the villagers from primary and secondary sources along with prevailing farming practices were documented. All the 114 soils of the village were deficient in N, while majority of soils were medium to high with respect to available P and K. The Soil fertility based fertilizer recommendations were advocated to every individual farmer based on their soil test report for the crop grown. Soil fertility maps were prepared and displayed in the village Panchayat. Bridging of the identified extension and research gaps was planned by proposing relevant technological interventions for the enhancement of livelihoods.

Multi-omics data integration for the identification of biomarkers for bull fertility.

Bull fertility is an important economic trait, and the use of subfertile semen for artificial insemination decreases the global efficiency of the breeding sector. Although the analysis of semen functional parameters can help to identify infertile bulls, no tools are currently available to enable precise predictions and prevent the commercialization of subfertile semen. Because male fertility is a multifactorial phenotype that is dependent on genetic, epigenetic, physiological and environmental factors, we hypothesized that an integrative analysis might help to refine our knowledge and understanding of bull fertility. We combined -omics data (genotypes, sperm DNA methylation at CpGs and sperm small non-coding RNAs) and semen parameters measured on a large cohort of 98 Montbéliarde bulls with contrasting fertility levels. Multiple Factor Analysis was conducted to study the links between the datasets and fertility. Four methodologies were then considered to identify the features linked to bull fertility variation: Logistic Lasso, Random Forest, Gradient Boosting and Neural Networks. Finally, the features selected by these methods were annotated in terms of genes, to conduct functional enrichment analyses. The less relevant features in -omics data were filtered out, and MFA was run on the remaining 12,006 features, including the 11 semen parameters and a balanced proportion of each type of-omics data. The results showed that unlike the semen parameters studied the-omics datasets were related to fertility. Biomarkers related to bull fertility were selected using the four methodologies mentioned above. The most contributory CpGs, SNPs and miRNAs targeted genes were all found to be involved in development. Interestingly, fragments derived from ribosomal RNAs were overrepresented among the selected features, suggesting roles in male fertility. These markers could be used in the future to identify subfertile bulls in order to increase the global efficiency of the breeding sector.

Women’s subsistence strategies predict fertility across cultures, but context matters

While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested whether subsistence activities-incorporating market integration-are associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as "farmers" did not have higher fertility than others, while "foragers" did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence.

Alleviating summer heat stress in cowpea-baby corn intercropping with stress-reducing chemicals and fertility variations

Over the past century, the average surface temperature and recurrent heatwaves have been steadily rising, especially during the summer season, which is affecting the yield potential of most food crops. Hence, diversification in cropping systems with suitable fertilizer management is an urgent need to ensure high yield potential during the summer season. Since intercropping has emerged as an important strategy to increase food production, the present study comprises five intercropping systems in the main plot (sole cowpea, sole baby corn, cowpea + baby corn in 2:1, 3:1, and 4:1 row ratio), three levels of fertilizer viz. 100 (N20 P40), 125 (N25 P50), and 150% (N30 P60) recommended dose of fertilizer (RDF) in the subplot, along with two stress-mitigating chemicals (0.5% CaCl2 and 1% KNO3) in the sub-sub plots. A split-split plot system with four replications was established to carry out the field experiment. The effect of intercropping, fertilizer levels, and stress-mitigating chemicals on crop growth rate (CGR), relative growth rate (RGR), plant temperature, relative water content (RWC) and chlorophyll content of cowpea and baby corn, as well as cowpea equivalent yield (CEY), was investigated during the summer seasons of 2019 and 2020. The experiment was conducted at Agriculture University, Kota (Rajasthan), India. Results showed that CGR, RGR, RWC and chlorophyll content of both crops and CEY were maximum under intercropping of cowpea and baby corn in a 2:1 row ratio compared to other intercropping systems. However, the plant temperature of both crops was significantly lower under this system. CEY, CGR, RGR, and chlorophyll content were considerably greater in the subplots with a fertilizer application of 150% RDF compared to lower levels of fertilizer (100 and 125% RDF). Our findings further show that foliar application of CaCl2 0.5% at the flowering and pod-developing stages of cowpea dramatically boosted CEY, CGR, RGR, RWC, and chlorophyll content of both crops and lowered the plant temperature.

Changes in leaf lifespan, nitrogen resorption, and mean residence time of leaf nitrogen along a soil fertility gradient in an evergreen oak tree.

The ability of plants to retain nitrogen (N) for a long period of time is critical to their N use efficiency, growth, and fitness, particularly in infertile environments. The mean residence time of leaf N (MRTL) and its two determinants, leaf lifespan and N resorption efficiency (rN, the fraction of the total leaf N pool that is resorbed during leaf senescence), have been hypothesized to increase plastically with decreasing soil N fertility but this remains to be fully tested. To avoid confusion by random changes in these characteristics in a relatively narrow N fertility range, MRTL, leaf lifespan, and N resorption efficiency were measured in Quercus glauca over a broad N fertility range. In the high to moderate N fertility range, leaf lifespan and rN increased with decreasing N addition rate, and thus the MRTL increased. However, in the moderate to low N fertility range, leaf lifespan increased but rN decreased significantly, so MRTL decreased. The decrease in rN occurred because the senesced leaf N concentration was almost constant at the lower limit while the green leaf N concentration decreased in this range. The hump-shaped quadratic responses of MRTL and rN along the N fertility gradient suggest that incorrect conclusions about the response of these traits to N fertility variation may be drawn from experiments that include only a few fertility levels, and N recycling within leaf canopy alone cannot achieve efficient N use in infertile environments.

MSH7 confers quantitative variation in pollen fertility and boosts grain yield in maize.

Fertile pollen is critical for the survival, fitness, and dispersal of flowering plants, and directly contributes to crop productivity. Extensive mutational screening studies have been carried out to dissect the genetic regulatory network determining pollen fertility, but we still lack fundamental knowledge about whether and how pollen fertility is controlled in natural populations. We used a genome-wide association study (GWAS) to show that ZmGEN1A and ZmMSH7, two DNA repair-related genes, confer natural variation in maize pollen fertility. Mutants defective in these genes exhibited abnormalities in meiotic or post-meiotic DNA repair, leading to reduced pollen fertility. More importantly, ZmMSH7 showed evidence of selection during maize domestication, and its disruption resulted in a substantial increase in grain yield for both inbred and hybrid. Overall, our study describes the first systematic examination of natural genetic effects on pollen fertility in plants, providing valuable genetic resources for optimizing male fertility. In addition, we find that ZmMSH7 represents a candidate for improvement of grain yield.