Flooding depths and burial effects on seedling emergence of five California weedy rice (Oryza sativa spontanea) accessions

Weed Science ◽  
2022 ◽  
pp. 1-22
Author(s):  
Liberty B. Galvin ◽  
Deniz Inci ◽  
Mohsen Mesgaran ◽  
Whitney Brim-DeForest ◽  
Kassim Al-Khatib

Abstract Weedy rice (Oryza sativa f. spontanea Roshev.) has recently become a significant botanical pest in California rice (Oryza sativa L.) production systems. The conspecificity of this pest with cultivated rice, Oryza sativa (L.), negates the use of selective herbicides, rendering the development of non-chemical methods a necessary component of creating management strategies for this weed. Experiments were conducted to determine the emergence and early growth responses of O. sativa spontanea to flooding soil and burial conditions. Treatment combinations of four flooding depths (0, 5, 10, and 15 cm) and four burial depths (1.3, 2.5, 5, and 10 cm) were applied to test the emergence of five O. sativa spontanea accessions as well as ‘M-206’, a commonly used rice cultivar in California, for comparison. Results revealed that burial depth had a significant effect on seedling emergence. There was a 43-91% decrease in emergence between seedlings buried at 1.3 and 2.5 cm depending on the flooding depth and accession, and an absence of emergence from seedlings buried at or below 5 cm. Flooding depth did not affect emergence, but there was a significant interaction between burial and flooding treatments. There was no significant difference between total O. sativa spontanea emergence from the soil and water surfaces regardless of burial or flooding depths, implying that once the various accessions have emerged from the soil they will also emerge from the floodwater. Most accessions had similar total emergence compared to M-206 cultivated rice, but produced more dry weight than M-206 when planted at 1.3 cm in the soil. The results of this experiment can be used to inform stakeholders of the flooding conditions necessary as well as soil burial depths that will promote or inhibit the emergence of California O. sativa spontanea accessions from the weed seedbank.

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 385-388 ◽  
Author(s):  
Bhagirath Singh Chauhan

Weedy rice is a serious problem of cultivated rice in most of the rice-growing areas in Asia, causing increased production costs and yield losses in rice. A study was conducted to determine the response of weedy rice accessions from India (IWR), Malaysia (MWR), Thailand (TWR), and Vietnam (VWR) to seed burial and flooding depths. The greatest emergence for each weedy rice accession (97% for IWR, 82% for MWR, 97% for TWR, and 94% for VWR) was observed in seeds placed on the soil surface. Seedling emergence decreased with increase in burial depth. For the IWR accession, 0.5% of the seedlings emerged from 8-cm depth, whereas for the other three weedy rice accessions, no seedlings emerged from this depth. When seeds were sown on the soil surface, flooding depth ranging from 0 to 8 cm had no or very little effect on seedling emergence of different weedy rice accessions. On the other hand, flooding decreased seedling emergence in all weedy rice accessions when seeds were sown at 1 cm deep into the soil. Compared with seedling emergence, flooding had a more pronounced effect on seedling biomass for all weedy rice accessions. A flooding depth of 2 cm reduced seedling biomass by an amount greater than 85% of each weedy rice accession. The results of this study suggest that emergence and growth of weedy rice could be suppressed by deep tillage that buries seeds below their maximum depth of emergence (i.e., > 8 cm for the accessions studied) and by flooding fields as early as possible. The information gained from this study may help design cultural management strategies for weedy rice in Asia.


Weed Science ◽  
2021 ◽  
pp. 1-37
Author(s):  
Leonard Bonilla Piveta ◽  
José Alberto Noldin ◽  
Nilda Roma-Burgos ◽  
Vívian Ebeling Viana ◽  
Lariza Benedetti ◽  
...  

Abstract Weedy rice (Oryza sativa L.) is one of the most troublesome weeds affecting rice (Oryza sativa L.) production in many countries. Weedy rice control is difficult in rice fields because the weed and crop are phenotypically and morphologically similar. Weedy rice can be a source of genetic diversity to cultivated rice. Thus, this study aimed to characterize the morphological diversity of weedy rice in Southern Brazil. Qualitative and quantitative traits of 249 accessions from eight rice growing mesoregions in Rio Grande do Sul (RS) and Santa Catarina (SC) states were analyzed. For each accession, 24 morphological descriptors (14 qualitative and 10 quantitative) were evaluated. All the 249 accessions from RS and SC are of indica lineage. Considering all the phenotypic traits evaluated, the accessions separated into 14 distinct groups. One of the largest groups consisted of plants that were predominantly tall and with green leaves, intermediate shattering, and variable in flowering time. Distinct subgroups exist within larger clusters, showing discernable phenotypic diversity within the main clusters. The variability in flowering time was high (77 to 110 d after emergence), indicating high potential for flowering synchrony with rice cultivars and, consequently, gene flow. This indicates the need to remove escapes when planting herbicide-resistant rice. Thus, weedy rice populations in Southern Brazil are highly diverse and this diversity could result in variable response to weed management.


Weed Science ◽  
2011 ◽  
Vol 59 (2) ◽  
pp. 182-187 ◽  
Author(s):  
Grace E-K. Bolfrey-Arku ◽  
Bhagirath S. Chauhan ◽  
David E. Johnson

Itchgrass is a weed of many crops throughout the tropics and one of the most important grass weeds of rainfed rice. Experiments were conducted in the laboratory and screenhouse to determine the effects of light, alternating day/night temperatures, high temperature pretreatment, water stress, seed burial depth, and rice residue on seed germination and seedling emergence of itchgrass in the Philippines. Two populations were evaluated and the results were consistent for both populations. Germination in the light/dark regime was greater at alternating day/night temperatures of 25/15 C than at 35/25, 30/20, or 20/10 C. Light was not a requirement for germination, but a light/dark regime increased germination by 96%, across temperature and population. A 5-min high temperature pretreatment for 50% inhibition of maximum itchgrass germination ranged from 145 to 151 C with no germination when seeds were exposed to ≥ 180 C. The osmotic potential required for 50% inhibition of maximum germination was −0.6 MPa for itchgrass, although some seeds germinated at −0.8 MPa. Seedling emergence was greatest for seeds placed on the soil surface, and emergence declined with increasing soil burial depth; no seedlings emerged from seeds buried at 10 cm. The addition of rice residue to soil surface in pots at rates equivalent to 4 to 6 Mg ha−1reduced itchgrass seedling emergence. Since seedling emergence was greatest at shallow depths and germination was stimulated by light, itchgrass may become a problem in systems where soil is cultivated at shallow depths. Knowledge gained in this study could contribute to developing components of integrated weed management strategies for itchgrass.


2014 ◽  
Vol 513-517 ◽  
pp. 4277-4280
Author(s):  
Li Li ◽  
Che Wang ◽  
Qian Liang ◽  
Dian Rong Ma ◽  
Wen Fu Chen

Mesocotyl elongation in rice is essential for seedling emergence. Our previous screening identified weedy rice accessions (Oryza sativa f. spontanea L.) (WR04-6) with unusual long mesocotyl. In this study, using rice cultivar Akihikari (Oryza sativa, subspecies japonica) as control, we observed that weedy rice accessions display more extensive microtubules (MTs) depolymerization in the early stage of mesocotyl elongation. At the end of mesocotyl elongation, the predominant MTs in weedy rice are transversely oriented, while, Akihikari has oblique MTs arrays.


2014 ◽  
Vol 55 ◽  
pp. 42-49 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
Anuruddhika S.K. Abeysekera ◽  
Manoja S. Wickramarathe ◽  
Sakinda D. Kulatunga ◽  
Upali B. Wickrama

Weed Science ◽  
2020 ◽  
Vol 68 (5) ◽  
pp. 485-495
Author(s):  
Elizabeth Karn ◽  
Teresa De Leon ◽  
Luis Espino ◽  
Kassim Al-Khatib ◽  
Whitney Brim-DeForest

AbstractWeedy rice (Oryza sativa f. spontanea Rosh.) is an emerging weed of California rice (Oryza sativa L.) that has potential to cause large yield losses. Early detection of weedy rice in the field is ideal to effectively control and prevent the spread of this weed. However, it is difficult to differentiate weedy rice from cultivated rice during early growth stages due to the close genetic and phenotypic relatedness of cultivated rice and weedy rice. The objective of this study is to examine phenotypic variation in weedy rice biotypes from California and to identify traits that could be used to visually identify weedy rice infestations at early growth stages for effective management. Greenhouse experiments were conducted in 2017 and 2018 using five phenotypically distinct biotypes of weedy rice found in California, along with diverse cultivated, weedy, and wild rice types in a randomized complete block design. We measured variation for 13 phenotypic traits associated with weedy rice and conducted principal component analysis and factor analysis to identify important weedy traits. Most weedy rice individuals within a biotype clustered together by phenotypic similarity. Pericarp color, hull color, chlorophyll content, grain length, plant height, leaf pubescence, collar color, and leaf sheath color account for most of the observed variation. California weedy rice biotypes are phenotypically distinct from wild rice and from weedy rice from the southern United States in their combinations of seed phenotypes and vegetative characteristics. In comparison with the locally grown temperate japonica cultivars, California weedy rice tends to be taller, with lower chlorophyll content and a red pericarp. Weedy rice biotypes vary in seed shattering and seed dormancy. For weedy rice management, plant height and chlorophyll content are distinct traits that could be used to differentiate weedy rice from the majority of cultivated rice varieties in California during vegetative stages of rice growth.


Weed Science ◽  
2019 ◽  
Vol 67 (2) ◽  
pp. 261-266 ◽  
Author(s):  
Iraj Nosratti ◽  
Sajad Almaleki ◽  
Bhagirath S. Chauhan

AbstractSoldier thistle [Picnomon acarna(L.) Cass.] is widely distributed throughout rainfed fields across western Iran, where it decreases crop yields and interferes with harvest operations. This study was conducted to determine the influence of different factors on seed germination and seedling emergence ofP. acarna. Freshly harvested seeds were dormant and required an after-ripening period for breaking dormancy. Seed germination was greatly promoted by light. Germination occurred over a wide spectrum of constant and fluctuating temperature regimes, ranging from 5 to 35 C, with highest germination at constant (74%) and fluctuating (94%) temperatures of 20 and 20/10 C. Seed germination ofP. acarnawas tolerant to osmotic potential, while salt stress significantly inhibited its germination percentage. pH was not an inhibiting factor for germination ofP. acarnaseeds. Seedling emergence decreased exponentially with an increase in seed burial depth in the soil; at soil burial depths of 4 cm or greater, no seedlings were able to reach the soil surface. The results suggest that significant seed germination ofP. acarnain rainfed fields is possible, and the weed has great potential to spread throughout rainfed systems in western Iran. Based on these results, effective control ofP. acarnacan be achieved by applying interrow cultivation in row crops and deep tillage at seedbed preparation.


Planta ◽  
2009 ◽  
Vol 231 (3) ◽  
pp. 559-570 ◽  
Author(s):  
Yong Wang ◽  
Zheng Zheng Zhong ◽  
Zhi Gang Zhao ◽  
Ling Jiang ◽  
Xiao Feng Bian ◽  
...  

2020 ◽  
Author(s):  
Can Zhao ◽  
Wenrong Xu ◽  
Zheng Zhang ◽  
Lingchao Meng ◽  
Weimin Dai ◽  
...  

Abstract Background: Shorter grain-filling period and rapid endosperm development contributes to early maturity in weedy rice (Oryza sativa L. f. spontanea). However, the differences in programmed cell death (PCD) process and anti-oxidative enzymes system in the caryopsis between weedy and cultivated rice are largely unexplored. Main Text: we selected four biotypes of weedy rice and associated cultivated rice (ACR, Oryza sativa) from different latitudes to conduct a common garden experiment. The difference of PCD process between weedy rice and ACR was compared by chemical staining, and the cell viability and nuclear morphometry of endosperm cells were observed by optical microscopy, and anti-oxidative enzymes activity were also measured during grain filling. We found that the PCD progress in weedy rice was more rapid and earlier than that in ACR. The percentage of degraded nuclei of weedy rice were 10%-83% higher than that of ACR. Endosperm cells in weedy rice lost cell viability 2-8 days earlier than that in ACR. The anti-oxidant enzymes activity of weedy rice were lower than that of ACR during grain filling. The ability of weedy rice to scavenge reactive oxygen species is weaker than that of ACR, which may contribute to the rapid PCD process in the endosperm cells of weedy rice. Conclusion: The rapid PCD process and weaker ability to scavenge reactive oxygen species in endosperm cells lead to the shorter grain-filling period of weedy rice.


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