Open AccessArticle

Winter Expansion and Emergence Time Effects on the Phenology, Growth, and Fecundity of Feathertop Rhodes Grass (Chloris virgata)

Alireza Hasanfard

and

Bhagirath Singh Chauhan

^2,*

Department of Agrotechnology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad 9177948974, Iran

Centre for Crop Science, Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Gatton, QLD 4343, Australia

Author to whom correspondence should be addressed.

Agronomy 2025, 15(1), 67; https://doi.org/10.3390/agronomy15010067

Submission received: 23 October 2024 / Revised: 8 December 2024 / Accepted: 24 December 2024 / Published: 30 December 2024

(This article belongs to the Special Issue Adaptation and Mitigation of Environmental Stress on Forage Crops and Turfgrass)

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Figure 1
The minimum and maximum daily air temperatures at the study site. Continuous arrows indicate the planting dates in the first year (2021–2022), and dashed arrows indicate the planting dates in the second year (2022–2023). May (D1), July (D2), September (D3), November (D4), January (D5), and March (D6). Temperature data were collected from the Gatton Bureau of Meteorology Weather Station, located within 500 m of the experimental site. "> Figure 2
The impact of planting dates and populations on the plant height (A,B), tiller production (C,D), and panicle production (E,F) of feathertop Rhodes grass between 2021 and 2022 and between 2022 and 2023. The error bars represent the standard error of the mean. "> Figure 2 Cont.
The impact of planting dates and populations on the plant height (A,B), tiller production (C,D), and panicle production (E,F) of feathertop Rhodes grass between 2021 and 2022 and between 2022 and 2023. The error bars represent the standard error of the mean. "> Figure 3
The impact of planting dates and populations on the biomass (A,B) and seed production (C,D) of feathertop Rhodes grass between 2021 and 2022 and between 2022 and 2023. The error bars represent the standard error of the mean. "> Figure 3 Cont.
The impact of planting dates and populations on the biomass (A,B) and seed production (C,D) of feathertop Rhodes grass between 2021 and 2022 and between 2022 and 2023. The error bars represent the standard error of the mean. "> Figure 4
Pearson correlation coefficient matrix between growth attributes and seed production of feathertop Rhodes grass between 2021 and 2022 and between 2022 and 2023. Asterisks denote significant differences: * p ≤ 0.05 and ** p ≤ 0.01. ">

Versions Notes

Abstract

Feathertop Rhodes grass (Chloris virgata Sw.) is a problematic weed in Australian summer crop fields that has recently expanded its presence into colder seasons. In this study, the phenology, growth, and seed production of four C. virgata populations were investigated across six different planting dates every other month from May to March between 2021 and 2022 and between 2022 and 2023. In both years, the shortest time (3 to 6 days) for C. virgata emergence was observed for January planting, while the longest time (10 to 17 days) was observed for July planting. In both years, C. virgata populations showed variations in growth and seed production in response to planting time. The highest aboveground biomass production in the first year was observed in November planting, and in the second year, it was observed in both November and January plantings. In the first year, all four populations produced the highest number of seeds when planted in January, averaging 133,000 seeds plant⁻¹. In the second year, among the different planting dates, the March planting with two populations resulted in the highest seed production, averaging 148,000 seeds plant⁻¹. In both years, there was a positive and significant correlation between aboveground biomass and seed production. The ability of this species to emerge, establish, survive, and consistently produce seeds year-round indicates its successful adaptation to the Queensland climate. Failure to manage this weed will result in its further spread to new areas.

Keywords:

adaptation; distribution; genetic variation; seed production

1. Introduction

Weeds pose a significant challenge as a biological constraint in various cropping systems worldwide, impacting agricultural productivity and sustainability. One common warm-season annual weed in Australia is feathertop Rhodes grass (FTR) (Chloris virgata Sw.), which can be a significant issue in agricultural fields and pastures [1,2]. Its rapid growth and prolific seed production make it a challenging weed to manage, requiring effective control measures to prevent its spread and impact on crop yields [1]. Chloris virgata has the capability to produce over 600 g m⁻² of dry matter and is known for its high seed production, with more than 40,000 seeds plant⁻¹ [3]. In fallow conditions, this weed can produce more than 140,000 seeds plant⁻¹ [4].

Chloris virgata is a common weed in summer crops, such as mungbean [Vigna radiata (L.) Wilczek], sorghum (Sorghum bicolor L. Moench) and cotton (Gossypium hirsutum L.), grown across the subtropical region of Australia [5,6]. Chloris virgata seeds have the ability to germinate across a broad temperature spectrum, ranging from 5 to 40 °C [1,7]. However, their optimal germination occurs within the narrower range of 15–25 °C [1,7]. This adaptability to varying temperatures allows for successful germination in a range of environmental conditions, showcasing the resilience and versatility of these seeds. Chloris virgata thrives in tropical, subtropical, and warm temperate regions, and can also be found in temperate regions where hot summers are common [8]. The adaptability of C. virgata to various climates underscores its ability to thrive and expand seasonally in diverse environmental settings.

Weed emergence time plays a crucial role in determining the phenology, growth, and fecundity of weeds. Early-emerging weeds may have a longer growing season to accumulate biomass and produce seeds, thereby enhancing their reproductive success [1,9]. On the other hand, weeds that emerge later may have limited time to grow and reproduce before the end of the growing season. A study on several weed species, including Avena fatua, A. sterilis, Phalaris paradoxa, and Rapistrum rugosum, conducted in Queensland, Australia, revealed that seed production was higher in plants that emerged earlier in the growing season [9]. For winter-growing species, emergence from April to June (mid-autumn to early winter) resulted in higher seed production, while for spring- and summer-growing species, emergence between August and December (late winter to early summer) led to higher seed production. In a study conducted in West Lafayette, Indiana, USA, a population of Amaranthus palmeri S. Watson produced approximately 50 seeds plant⁻¹ when it emerged late in the season (July planting) and approximately 19,000 seeds plant⁻¹ when it emerged early in the season (May planting) [10]. In a similar study, delayed weed emergence in rice (Oryza sativa L.) has been reported to significantly reduce weed seed production [11]. In another study, it was reported that the average biomass accumulation of Amaranthus tuberculatus (Mog.) J.D. Sauer from the establishment dates of May (1120 g plant⁻¹) and June (1069 g plant⁻¹) was higher than that from the July establishment date (266 g plant⁻¹) [12]. A study that evaluates multiple populations of a species in a single location can allow for direct comparisons between populations and can help demonstrate inherent differences among populations [13]. For example, Heneghan and Johnson [12] reported that seed production in five A. tuberculatus populations differed depending on their establishment timing.

Anecdotal evidence in recent years shows that in some areas of Australia, C. virgata has been observed not only in spring and summer but also in winter (May to August). Investigating the winter behavior of C. virgata is essential for several reasons. First, it can inform management strategies for this species, particularly in regions where it is considered a weed. Second, understanding how environmental conditions influence its growth can provide valuable insights into its adaptability and potential for range expansion. Lastly, studying the year-round growth patterns of C. virgata may illuminate broader ecological dynamics, including plant competition, nutrient cycling, and habitat suitability for other species. In addition, weeds that emerge at unexpected times may pose greater challenges for control using traditional weed management practices, as timing plays a crucial role in the effectiveness of herbicide application or mechanical removal. Weeds that emerge outside the normal season may have more time to produce seeds, leading to a larger seed bank and increased weed pressure in future growing seasons. Understanding the influence of emergence time and population density on reproductive plasticity is crucial for improving weed management strategies. Therefore, this study aims to compare the growth, phenology, and fecundity of C. virgata plants that emerge at various times throughout the year.

2. Materials and Methods

2.1. Seed Collection and Controlled Planting Conditions

Seeds from four populations of C. virgata were collected in 2017 from different crop situations in Queensland, Australia (Table 1). Seeds from each population were collected from a minimum of 50 plants and stored in plastic containers at room temperature (about 25 °C) until use. Only mature seeds were selected and collected by shaking the plants over a tray. By utilizing a single plant per pot, we were able to closely monitor the growth and development of individual weeds without interference from other plants, a scenario that would have been unfeasible under field conditions. The use of field soil from our farm in pots often results in excessive compaction and standing water, which creates suboptimal conditions for plant growth and leads to extremely hard soil. This negatively affects the reliability of the results. Consequently, the C. virgata populations were planted separately in plastic pots (24 cm in diameter and 30 cm in height) filled with a commercial potting mix (Centenary Landscaping, Mount Ommaney, Australia) from May 2021 to March 2023. This potting mix provided a controlled environment, ensuring consistent moisture levels and promoting optimal root growth.

Due to the unique challenges posed by field conditions, it was essential to conduct the study using pots. The high seed bank of the target weed in the field experiments complicated the differentiation between the experimental plants and the surrounding background population. This situation could have significantly compromised the accuracy and reliability of the collected data. Consequently, employing pots created a controlled environment that minimized these confounding factors, thereby ensuring more accurate and meaningful experimental results.

The first-year study was conducted from May 2021 to March 2022, and the second-year study was conducted from May 2022 to March 2023. There were six planting dates each year: May (D1), July (D2), September (D3), November (D4), January (D5), and March (D6). In the study region, autumn occurs from March to May and winter occurs from June to August. Therefore, in the first year of the study, some plants planted in May, and in the second year of the study, some plants planted in May (FTR 11 population entirely) and July were lost due to cold temperatures. There were six replications of each population for each planting time. Seeds (3-4) were planted at a depth of 0.5 cm in the center of each pot. The plants were irrigated using a sprinkler system three times a day for 10 min. Since no signs of nutritional deficiencies were detected during the experiment, fertilizer was not applied. Once emerged, only one plant pot⁻¹ was maintained. The pots were placed outdoors at the Gatton Research Farms (27.55° S, 152.34° E) at the University of Queensland, QLD, Australia.

2.2. Measurement of Traits

Plants were harvested when a quarter of the panicles had begun to shed seeds. The recorded attributes for C. virgata included plant height (measured from the soil surface to the tip of the uppermost leaf or panicle), number of tillers, number of panicles, plant dry matter, and number of seeds per plant. Dry matter of surviving plants was obtained by cutting them at the base with secateurs and placing them in paper bags. Subsequently, samples were dried in an oven at 70 °C for 72 h. Daily maximum and minimum temperatures were obtained from the Gatton Bureau of Meteorology Weather Station located within 500 m of the experimental site (Figure 1). Cumulative growing degree days (GDD) were calculated for each day after planting using the formula:

G D D = [\frac{d a i l y m a x i m u m t e m p e r a t u r e + d a i l y m i n i m u m t e m p e r a t u r e}{2}] - T b

where the base temperature (T_b) was considered to be 10 °C for summer weeds [4].

2.3. Statistical Analyses

The experiment was conducted using a factorial (planting time × population) randomized block design in each experimental year. Normality and homogeneity of variance of the dataset were assessed using the Shapiro–Wilk test and Levene’s test, respectively, before conducting ANOVA. No data transformation was necessary. Due to significant year effects, the data were analyzed separately for each year. The generalized linear model procedure (GLM PROC) of the SAS software (version 9.4, SAS Institute Inc., Cary, NC, USA) was used to analyze the data, and the means were compared using Fisher’s Least Significant Difference (LSD) test at a 5% probability level. Mean comparisons and the Pearson correlation coefficient between growth attributes and seed production of C. virgata were illustrated using GraphPad Prism software (version 9.0.0; GraphPad, San Diego, CA, USA).

3. Results

3.1. Phenological Stages

In both years, the shortest time for C. virgata emergence (3 to 6 days; 42 to 83 GDD) was observed when planted in January (Table 2). Meanwhile, emergence for July planting took the longest time (10 to 17 days; 34 to 63 GDD) for emergence. In both years, the lowest GDDs required for panicle emergence were observed for July planting (depending on population, 404 to 703 in 2021 to 2022 and 364 to 531 in 2022 to 2023) (Table 2). In the first year, January-planted populations required the greatest number of GDD (660 to 751) for panicle emergence, whereas in the second year, November-planted populations required the greatest number of GDD (652 to 778) for panicle emergence (Table 2). In the first year, the lowest GDD for C. virgata harvesting was 898 in March, while the highest was 1272 in July (Table 2). In the second year, the lowest GDD for C. virgata harvesting was 963 in September, while the highest was 1349 in January (Table 2).

3.2. Analysis of Variance

The analysis of variance regarding the growth characteristics and seed production of C. virgata indicated that the interaction between planting date and population was significant during the 2021–2022 and 2022–2023 growing seasons (Table 3).

3.2.1. Plant Height

Although plant height varied among populations and planting dates, in both years, the shortest C. virgata plants were found in May plantings, while the tallest plants were found in November plantings (Figure 2A,B). Based on the mean comparison test, the November planting (FTR3 and FTR8) and January planting (FTR8 and FTR9) were identified as the populations and planting dates with the highest plant height in both years (Figure 2A,B).

3.2.2. Tiller and Panicle Production

In general, the tiller and panicle production of C. virgata populations differed between two years, especially during May and July plantings (Figure 2C–F). In the first year, November planting had the highest number of populations (FTR3, FTR8, and FTR9) with the highest tiller production compared to other planting times. In the second year, March planting had the highest number of populations (FTR3, FTR8, FTR9, and FTR11) with the highest tiller production compared to other planting times (Figure 2C,D). For tiller production, the response of C. virgata populations was largely similar in March planting in both years. In the first year, the highest number of populations (FTR3, FTR8, and FTR11) with high panicle production belonged to the May planting. In the second year, the highest number of populations (FTR3, FTR8, FTR9, and FTR11) exhibiting high panicle production were from the March planting (Figure 2E,F).

Table 3. ANOVA of growth characteristics and seed production of feathertop Rhodes grass populations across different planting dates between 2021 and 2022 and between 2022 and 2023.

Source	Plant Height	Tiller Production	Panicle Production	Biomass	Seed Production
2021–2022
Planting date	<0.001 ***	0.011 *	0.008 **	<0.001 ***	<0.001 ***
Population	<0.001 ***	0.720	0.962	<0.001 ***	0.131
Planting date × Population	0.015 *	<0.001 ***	0.032 *	<0.001 ***	0.029 *
2022–2023
Planting date	<0.001 ***	<0.001 ***	<0.001 ***	<0.001 ***	<0.001 ***
Population	<0.001 ***	0.052	0.040 *	0.072	<0.001 ***
Planting date × Population	0.035 *	0.007 **	0.003 **	0.002 **	0.002 **

Asterisks denote the significance of p values: * p < 0.05; ** p < 0.01; *** p < 0.001.

Figure 2. The impact of planting dates and populations on the plant height (A,B), tiller production (C,D), and panicle production (E,F) of feathertop Rhodes grass between 2021 and 2022 and between 2022 and 2023. The error bars represent the standard error of the mean.

3.2.3. Biomass and Seed Production

In the first year, the highest biomass was observed in November planting with FTR3, FTR8, and FTR9 populations (Figure 3A). In the second year, all four populations that were planted in November and January had the highest biomass (Figure 3B). In general, the lowest biomass was observed in the FTR9 and FTR11 populations during May planting in the first year (Figure 3A). In the second year, populations planted in May and July exhibited the lowest biomass levels (Figure 3B).

In the first year, all four C. virgata populations produced the highest number of seeds when planted in January (Figure 3C). In the second year, the March planting had the highest population numbers (FTR3 and FTR8) with high seed production (Figure 3D). Similarly, in both years, two populations, FTR9 and FTR11, produced the fewest seeds when planted in May (Figure 3C,D). In the first year, the March planting had the highest number of populations (FTR3, FTR8, and FTR11) with the lowest seed production (Figure 3C). Interestingly, in the first year, the FTR11 population produced the lowest number of seeds in the four planting dates (May, September, November, and March). In the second year, this phenomenon was observed in two planting dates (May and July).

3.3. Correlation Analysis

Pearson’s correlation analysis was conducted on C. virgata population characteristics between 2021 and 2022 and between 2022 and 2023 (Figure 4). The most important positive and significant correlation was observed between seed production and C. virgata aboveground biomass (0.41* and 0.51** in the first and second years, respectively).

4. Discussion

Tracking weed phenology allows for assessing the impact of climate change on their behavior, which facilitates making informed decisions to adapt to changing environmental conditions. Colbach et al. [14] emphasized the influence of temperature on weed phenology, which plays a crucial role in determining their growth and development. In this study, the GDD required for panicle emergence of C. virgata were higher for plantings conducted in November and January during both years. Chloris virgata may prioritize vegetative growth over reproductive growth in early and mid-summer (November and January) to optimize resource acquisition and photosynthesis. This prioritization can delay panicle emergence and lead to an increased GDD requirement. Chloris virgata primarily infests spring and summer crops, and the extended emergence time observed in July in both years can be attributed to it being a midwinter month in Australia (Table 2). Furthermore, more optimal photoperiods facilitate faster development, while less optimal photoperiods result in slower development. The increasing photoperiod during spring and summer (about 14 h) is likely to be one of the factors contributing to the greater number of GDD required for panicle emergence in the November and January plantings of C. virgata. In a previous study conducted in Queensland, researchers found that delaying planting from October to January reduced the growth period and postponed the onset of flowering in Amaranthus retroflexus L. and Amaranthus viridis L. [15]. In recent years, the increased prevalence of C. virgata during colder seasons indicates a heightened adaptability to low temperatures. This phenomenon illustrates the species’ environmental flexibility and its capacity to complete its life cycle and proliferate effectively. One of the most significant reasons for this species’ adaptation to winter is its dormancy mechanisms, which likely enable it to survive cold temperatures and germinate under favorable conditions, thereby extending its growing season. The species may possess adaptive traits that allow it to tolerate lower temperatures and shorter daylight hours, enabling it to thrive during the winter months. Furthermore, there may be genetic variation within the species that allows certain populations to be more cold-tolerant and better suited to winter conditions, which is likely the case in the present study.

A decrease in temperature typically leads to reduced growth characteristics in plant species, such as plant height. Exposure to cold temperatures can diminish metabolic activity, slow growth, and inhibit nutrient uptake, which may contribute to stunted growth or even complete cessation. The drop in temperatures observed in May and July (Figure 1) during both growing seasons has led to a decrease in the height of C. virgata plants. It is likely that the cold temperatures disrupted the normal processes of cell division and expansion in seedlings, both of which are essential for growth. Consequently, this phenomenon has led to a reduction in plant height (Figure 2A,B).

Low temperatures can stimulate tiller production in certain plant species by triggering physiological responses promoting the development of new shoots, potentially increasing overall productivity. Therefore, in the present study, low temperatures are likely the cause of increased tiller production in certain C. virgata populations planted in May and July of the first year. However, the lack of additional tiller production in the same populations during the second year may be attributed to weather incompatibility, specifically a decrease in temperature. Similarly, increased tiller production in the first year (May and July planting) corresponded with heightened panicle production. This adaptation can lead to increased panicle production as C. virgata prioritizes reproductive growth in response to cold conditions, ensuring survival and reproduction. Similar to the first-year study, in the United States, Echinochloa crus-galli (L.) P. Beauv. produced a greater number of panicles when planted in May compared to late plantings from June to September [16]. Contrary to the second-year study, a previous study has shown that planting Echinochloa colona (L.) Link. in March resulted in the lowest number of panicles [17].

In both years, the biomass of C. virgata increased during the warmer seasons, particularly in November and January (Figure 1 and Figure 3A,B). In a similar study in Queensland, Australia, it was reported that E. colona populations planted in November had the highest biomass [17]. Probably, the warmer temperature was able to increase the photosynthetic activity of C. virgata plants, leading to increased biomass production. Furthermore, elevated temperatures can accelerate the germination of weed seeds and increase their growth rate, leading to an overall increase in biomass accumulation. Conversely, colder temperatures can impede weed growth and development, leading to a decrease in biomass production. In this study, the lowest biomass was also observed in May and July, coinciding with the lowest temperatures in both years (Figure 1 and Figure 3A,B).

By producing a large number of seeds, weeds increase their chances of survival and successful reproduction [18]. Furthermore, the ability of weeds to produce a large number of seeds enhances their resilience and enables them to thrive in various habitats. The noteworthy point in this study is that C. virgata seed production was observed across a wide range of planting dates in both years, even during the cold seasons of the year (Figure 3C,D), with the exception of the FTR11 population in May planting in the second year. In other words, the studied C. virgata populations demonstrate a high capability for germination, growth, and survival in all Queensland weather conditions, enabling them to enter the reproductive phase (seed production). This ability demonstrates the high adaptability of this weed to a wide range of weather conditions, ultimately facilitating its distribution and establishment in new locations. In a study, it was reported that A. palmeri exhibits varying levels of seed production at different planting dates [10]. Therefore, some weeds have adapted to thrive in various seasons and conditions, demonstrating the importance of seed production for weed survival and persistence. Seed production management is crucial for minimizing the introduction of weed seeds into the soil seed bank [19]. Research findings indicate that terminating common lambsquarters, common ragweed, and giant foxtail before they flower, as well as velvetleaf and jimsonweed two and three weeks after flowering, respectively, significantly reduces the influx of weed seeds into the seed bank [20].

Early planting can extend growth periods, resulting in increased biomass and higher seed yields. Conversely, delayed planting may shorten the time available for biomass accumulation and negatively impact reproductive success. However, this assertion may not apply to our study, particularly for certain populations, as earlier planting (in May and July) often leads to reduced biomass and seed production due to lower temperatures, as previously noted. Biomass serves as the energy source for plants to grow, reproduce, and produce seeds. In weeds, higher biomass production often correlates with increased seed production [21]. Chloris virgata populations with higher biomass production can grow larger, enabling them to produce more tillers and, ultimately, more seeds (Figure 4). Therefore, if left uncontrolled, C. virgata may form a large seed bank, making management increasingly challenging, especially considering the rapid escalation of glyphosate resistance observed in Queensland fields.

5. Conclusions

Observed differences in growth characteristics and seed production likely indicate inherent genetic variations among populations and variable growth potential of C. virgata. Despite varied responses to planting dates in both years, C. virgata demonstrated remarkable adaptability to germinate, emerge, survive, and eventually produce seeds across all seasons studied. This ability demonstrates the high adaptability of this weed to Queensland’s climate. As C. virgata is typically considered a summer weed, its presence during cold seasons may be overlooked, or conventional control methods may be ineffective. Thus, failure to implement appropriate control measures may lead to an increased density and distribution of C. virgata in the coming years. It is advisable to plant competitive native species or cover crops that can compete for resources with this species, thereby limiting its growth and spread.

Author Contributions

Conceptualization: B.S.C.; methodology: B.S.C.; software: A.H.; validation: B.S.C.; formal analysis: A.H.; investigation: B.S.C.; resources: B.S.C.; data curation: B.S.C.; writing—original draft preparation: A.H.; writing—review and editing: B.S.C.; and A.H.; supervision: B.S.C.; project administration: B.S.C. All authors have read and agreed to the published version of the manuscript.

Funding

The research received no funding.

Data Availability Statement

The original contributions presented in this study are included in the article; further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no potential conflicts of interest.

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Figure 1. The minimum and maximum daily air temperatures at the study site. Continuous arrows indicate the planting dates in the first year (2021–2022), and dashed arrows indicate the planting dates in the second year (2022–2023). May (D1), July (D2), September (D3), November (D4), January (D5), and March (D6). Temperature data were collected from the Gatton Bureau of Meteorology Weather Station, located within 500 m of the experimental site.

Figure 3. The impact of planting dates and populations on the biomass (A,B) and seed production (C,D) of feathertop Rhodes grass between 2021 and 2022 and between 2022 and 2023. The error bars represent the standard error of the mean.

Figure 4. Pearson correlation coefficient matrix between growth attributes and seed production of feathertop Rhodes grass between 2021 and 2022 and between 2022 and 2023. Asterisks denote significant differences: * p ≤ 0.05 and ** p ≤ 0.01.

Table 1. Seed collection information for feathertop Rhodes grass populations.

Population	Location	Crop Situation	Coordinates	Collection Date
FTR3	Chinchilla	Wheat fallow	−26.8264, 150.5802	March 2017
FTR8	St. George	Mungbean	−28.0916, 148.4271	April 2017
FTR9	St. George	Wheat fallow	−28.0454, 148.3158	April 2017
FTR11	Cecil Plains	Sorghum	−27.2935, 151.1283	April 2017

Table 2. Growing degree days for feathertop Rhodes grass seedling emergence, panicle emergence, and harvest when planted in different months between 2021 and 2022 and between 2022 and 2023.

Planting Date (month)		2021–2022			2022–2023
Planting Date (month)	Seedling Emergence	Panicle Emergence	Harvest	Seedling Emergence	Panicle Emergence	Harvest
D1 (May)	50–56 (9–10)	480-495 (102–106)	1109 (169)	48–70 (4–7)	530–704 (116–136)	1107 (177)
D2 (July)	34–39 (10–11)	404–703 (70–99)	1272 (143)	43–63 (11–17)	364–531 (70–89)	1208 (148)
D3 (September)	54–62 (7–8)	490–577 (46–54)	1084 (92)	43–51 (5–6)	433–630 (45–64)	963 (90)
D4 (November)	56–70 (5–6)	645–794 (47–57)	1249 (88)	50–59 (4–5)	652–778 (50–58)	1225 (87)
D5 (January)	63 (4)	660–751 (46–52)	1093 (78)	42–83 (3–6)	612–777 (40–51)	1349 (96)
D6 (March)	64–76 (5–6)	485–541 (40–46)	898 (94)	68–102 (4–6)	526–581 (43–50)	1125 (158)

Values in parentheses represent the number of days plants took for seedling emergence, panicle emergence, and harvest.

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Hasanfard, A.; Chauhan, B.S. Winter Expansion and Emergence Time Effects on the Phenology, Growth, and Fecundity of Feathertop Rhodes Grass (Chloris virgata). Agronomy 2025, 15, 67. https://doi.org/10.3390/agronomy15010067

AMA Style

Hasanfard A, Chauhan BS. Winter Expansion and Emergence Time Effects on the Phenology, Growth, and Fecundity of Feathertop Rhodes Grass (Chloris virgata). Agronomy. 2025; 15(1):67. https://doi.org/10.3390/agronomy15010067

Chicago/Turabian Style

Hasanfard, Alireza, and Bhagirath Singh Chauhan. 2025. "Winter Expansion and Emergence Time Effects on the Phenology, Growth, and Fecundity of Feathertop Rhodes Grass (Chloris virgata)" Agronomy 15, no. 1: 67. https://doi.org/10.3390/agronomy15010067

APA Style

Hasanfard, A., & Chauhan, B. S. (2025). Winter Expansion and Emergence Time Effects on the Phenology, Growth, and Fecundity of Feathertop Rhodes Grass (Chloris virgata). Agronomy, 15(1), 67. https://doi.org/10.3390/agronomy15010067

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