Early-maturing Cultivars Research Articles

Phenotypic Variability among Parental Lines and Progenies of Bread Wheat

Wheat is the second most important cereal staple food crop consumed nearly 35% of world population and provides 20% food calories. It’s a self-pollinating annual plant in the true grass family Gramineae (Poaceae) and genus Triticum, is the world’s most famous energy rich cereal crop. The wheat is a hexaploid (allohexaploid) species (2n =6x= 42) having AABBDD with A, B and D genome. The present research investigates fifty-six genotypes of bread wheat consisting of 33 F1s obtained by crossing eleven lines with three varieties in a line x tester mating design along with their parents and two well-known checks. The experiment was laid out in a randomized block design with three replications. Results revealed considerable genetic variability among the genotypes. Traits like grain yield per plant and number of tillers per plant exhibited higher values of PCV with moderate GCV. High heritability with moderate values of genetic advance were recorded for grain weight per spike (17.688%) followed by number of grains per spike (17.4 %), biological yield per plant (14.7 %), 1000 grain weight (11.9 %) indicating involvement of additive gene action in the inheritance of these traits and hence selection along with progeny testing can be employed for improvement of these characters. According to correlation studies, there is a substantial positive link between the trait grain yield per plant and the number of tillers per plant, harvest index, and biological yield per plant. Selection for these qualities will therefore eventually contribute to the genotypes' increased total output. Early maturing cultivars should be chosen when breeding for a better yield because it was also shown that the number of days to maturity had a negative correlation with the yield.

Integrating RTM-GWAS and meta‑QTL data revealed genomic regions and candidate genes associated with the first fruit branch node and its height in upland cotton.

Two genomic regions associated with FFBN and HFFBN and a potential regulatory gene (GhE6) of HFFBN were identified through the integration of RTM-GWAS and meta‑QTL analyses. Abstract The first fruit branch node (FFBN) and the height of the first fruit branch node (HFFBN) are two important traits that are related to plant architecture and early maturation in upland cotton. Several studies have been conducted to elucidate the genetic basis of these traits in cotton using biparental and natural populations. In this study, by using 9,244 SNP linkage disequilibrium block (SNPLDB) loci from 315 upland cotton accessions, we carried out restricted two-stage multilocus and multiallele genome-wide association studies (RTM-GWASs) and identified promising haplotypes/alleles of the four stable and true major SNPLDB loci that were significantly associated with FFBN and HFFBN. Additionally, a meta-quantitative trait locus (MQTL) analysis was conducted on 274 original QTLs that were reported in 27 studies, and 40 MQTLs associated with FFBN and HFFBN were identified. Through the integration of the RTM-GWAS and meta‑QTL analyses, two stable and true major SNPLDBs (LDB_5_15144433 and LDB_16_37952328) that were distributed in the two MQTLs were identified. Ultimately, 142 genes in the two genomic regions were annotated, and three candidate genes associated with FFBN and HFFBN were identified in the genomic region (A05:14.64-15.64Mb) via RNA-Seq and qRT‒PCR. The results of virus-induced gene silencing (VIGS) experiments indicated that GhE6 was a key gene related to HFFBN and that GhDRM1 and GhGES were important genes associated with early flowering in upland cotton. These findings will aid in the future identification of molecular markers and genetic resources for developing elite early-maturing cultivars with ideal plant characteristics.

GhGASA14 regulates the flowering time of upland cotton in response to GA3.

The silencing of GhGASA14 and the identification of superior allelic variation in its coding region indicate that GhGASA14 may positively regulate flowering and the response to GA3. Gibberellic acid-stimulated Arabidopsis (GASA), a member of the gibberellin-regulated short amino acid family, has been extensively investigated in several plant species and found to be critical for plant growth and development. However, research on this topic in cotton has been limited. In this study, we identified 38 GhGASAs that were dispersed across 18 chromosomes in upland cotton, and all of these genes had a GASA core domain. Transcriptome expression patterns and qRT-PCR results revealed that GhGASA9 and GhGASA14 exhibited upregulated expression not only in the floral organs but also in the leaves of early-maturing cultivars. The two genes were functionally characterized by virus-induced gene silencing (VIGS), and the budding and flowering times after silencing the target genes were later than those of the control (TRV:00). Compared with that in the water-treated group (MOCK), the flowering period of the different fruiting branches in the GA3-treated group was more concentrated. Interestingly, allelic variation was detected in the coding sequence of GhGASA14 between early-maturing and late-maturing accessions, and the frequency of this favorable allele was greater in high-latitude cotton cultivars than in low-latitude ones. Additionally, a significant linear relationship was observed between the expression level of GhGASA14 and flowering time among the 12 upland cotton accessions. Taken together, these results indicated that GhGASA14 may positively regulate flowering time and respond to GA3. These findings could lead to the use of valuable genetic resources for breeding early-maturing cotton cultivars in the future.

Root systems of peanut cultivars respond differently to soil P availability to improve P uptake

AbstractBackgroundPeanut (Arachis hypogaea L.) is regarded as a crop with high nutrient use efficiency, but there may be differences between cultivars. Furthermore, there is little information on the strategy of peanut cultivars to adapt to soil P availability and to what extent they explore non‐labile P pools.AimsOur objective was to evaluate growth, root morphology, enzymatic activity in the rhizosphere, and P uptake of peanut cultivars grown under different soil P status.MethodsThe study was conducted in a greenhouse in 6‐L pots. Soils with low P (without fertilization) and high P content (with fertilization) and seven peanut cultivars of different origins, different maturation groups, and release years were investigated. Peanut shoot yield, phosphorus uptake, root growth, soil P fractions as well as phosphatase activity in the rhizosphere soil were determined.ResultsIn P‐deficient soil, a higher dry matter yield was associated with longer root hairs and root length, which resulted in decreased soil non‐labile P was observed mainly with cultivars developed in Argentina (ARG‐medium‐old and ARG‐medium‐new) and the late maturity Brazilian cultivar (BR I‐late new). These cultivars adapted well to P deficiency and were less dependent on labile P. New Brazilian early and medium maturity cultivars developed less, shorter root hairs, and showed low acid phosphatase activity in the rhizosphere under P deficiency, resulting in lower P uptake and dry matter yield. Under high P availability, new Brazilian cultivars of medium and late maturity showed the highest dry matter yield (9.0 and 9.8 g plant−1, respectively) and longest roots, around 120 m plant−1. High P availability decreased root hairs in all cultivars.ConclusionOverall, the adaptation of peanut cultivars to P‐deficient soils was lower for the new mid‐ and early‐maturing Brazilian cultivars compared with the Argentinian and old or late‐maturing Brazilian cultivars. The main strategies of P‐efficient cultivars under low P availability are to increase root length, root hair length, and root hair density.

Yield gap analysis and the relative importance of factors explaining yield variability in paddy fields

Closing the yield gap of strategic crops can facilitate achieving sustainable solutions to alleviate hunger, ensure food security, and enhance nutrition. This study aimed to quantify factors affecting rice yield gap in northern Iran using experimental and survey data on yields and management practices. The CERES-Rice model, calibrated with data (2011, 2016, 2019) from two regions, was used to estimate potential yield (Yp) of different rice cultivars. Yield gaps were calculated as the difference between economic yield potential and the average yield attained by farmers. The calibration process showed that cultivar coefficients varied across rice varieties. The simulated yields (2012–2021) showed that the mean potential yields were 13362 kg ha−1 and 8818 kg ha−1 for the late and early-maturing cultivars, respectively. High temperature was the most important yield defining factor across the rice growing areas. The yield gap was 3751 kg ha−1 and 2830 kg ha−1 in the late- and early-maturing cultivars, respectively. Nitrogen fertilizer rate, number of fertilizer applications, phosphorus fertilizer rate, transplanting date, potassium fertilizer rate, and seedling age were the top factors influencing the yield gap. Among the management factors, rice fertilizer management explained about 65% of the yield variability. Together, transplanting date and seedling age explained 15.3% of the variability in rice production, while pest, disease, and weed damage accounted for 9.6%. Breaking down the yield gap into affecting factors allows growers to improve the production system by providing the best crop management according to their facilities and capabilities. This approach is essential for optimizing agricultural productivity and achieving sustainable food production goals.

Metabolome and Transcriptome Analysis Provide Insights into Flower Bud Color Variation in the Adaptation to UV-B Radiation of Litchi

Flower color variations have increasingly been recognized as playing an important role in the adaptation to UV-B radiation; however, the underlying mechanism is poorly understood in perennial fruit trees. Litchi is an important fruit tree, and extremely early maturing (EEM) and middle-to-late-maturing (MLM) cultivars that originated from regions with high and low UV-B radiation have dark brown and light yellow flower buds, respectively, while their hybrid early-maturing (EM) cultivars have an intermediate brown flower bud. This study comprehensively analyzed the metabolome and transcriptome of flower buds of litchi EEM, EM and MLM cultivars to explore the mechanism underlying flower color variation during the adaptation to UV-B radiation for the first time. Metabolomic analysis identified 72 flavonoids in litchi flower buds, among which a higher accumulation of flavonol glycosides was responsible for darker flower buds of EEM cultivars. And transcriptome analysis revealed key structural genes, including LcCHI, LcFLS and seven UGTs, together with two transcription factors (LcMYB12 and LcMYB111), which could be directly up-regulated by UV-B radiation, playing critical roles in regulating the differential accumulation of flavonol glycosides. These results provide new insights into the molecular mechanism underlying adaptation to UV-B radiation and provide a genetic basis for future breeding of stress-tolerant cultivars of litchi.

Irrigation Response, Water Use, and Lint Yield of Upland Cotton Cultivars

Highlights In-season crop water use and canopy temperatures after first square did not differ among cultivars. Lint yield was significantly affected by cultivar in all study years. Cultivar effects on lint yield were significant only at higher irrigation levels. Crop water productivity increased with increasing irrigation in two of the three study years. Abstract. Upland cotton (Gossypium hirsutum L.) production requires less irrigation compared with other crops and thus provides an opportunity to reduce risk and maintain profitability in areas where water is limited. Water use, canopy temperature, lint yield, and crop water productivity were evaluated for four early to medium maturity upland cotton cultivars under three levels (100%, 66%, and 33%) of alternate furrow subsurface drip irrigation (SDI) in a thermally limited environment. Crop evapotranspiration (ET) across cultivars and years averaged 627, 547, and 467 mm for the 100%, 66%, and 33% irrigation levels, respectively, and did not differ among cultivars (P > 0.05). Changes in stored soil water within each irrigation level were similar among cultivars, with significant differences occurring infrequently. Measured canopy temperatures from first white flower to two weeks after cutout did not significantly differ among cultivars (P > 0.10) within each irrigation level. Crop water use during boll maturation, as inferred from the developed crop coefficient curve, was considerably less than reported by other studies, signifying that irrigation could be terminated earlier without reducing lint yield. The cultivar effect on lint yield was significant in all study years (P < 0.001), but only at the 66% and 100% irrigation levels, with one cultivar exceeding the average yields of all evaluated cultivars by 13% across the three study years. Medium maturity cultivars usually yielded less than early maturity cultivars, especially for a year with less accumulation of thermal energy. Crop selection and late season irrigation water management were both key to improving cotton water productivity. Keywords: Upland cotton, Subsurface drip irrigation, Water productivity, Root water uptake, Canopy temperature.

An LcMYB111-LcHY5 Module Differentially Activates an LcFLS Promoter in Different Litchi Cultivars

Flavonol synthase (FLS) is the crucial enzyme of the flavonol biosynthetic pathways, and its expression is tightly regulated in plants. In our previous study, two alleles of LcFLS, LcFLS-A and LcFLS-B, have been identified in litchi, with extremely early-maturing (EEM) cultivars only harboring LcFLS-A, while middle-to-late-maturing (MLM) cultivars only harbor LcFLS-B. Here, we overexpressed both LcFLS alleles in tobacco, and transgenic tobacco produced lighter-pink flowers and showed increased flavonol levels while it decreased anthocyanin levels compared to WT. Two allelic promoters of LcFLS were identified, with EEM cultivars only harboring proLcFLS-A, while MLM cultivars only harbor proLcFLS-B. One positive and three negative R2R3-MYB transcription regulators of LcFLS expression were identified, among which only positive regulator LcMYB111 showed a consistent expression pattern with LcFLS, which both have higher expression in EEM than that of MLM cultivars. LcMYB111 were further confirmed to specifically activate proLcFLS-A with MYB-binding element (MBE) while being unable to activate proLcFLS-B with mutated MBE (MBEm). LcHY5 were also identified and can interact with LcMYB111 to promote LcFLS expression. Our study elucidates the function of LcFLS and its differential regulation in different litchi cultivars for the first time.

Phenological assessment of early-maturing soybean accessions (Glycine max (L.) Merr.) under the conditions of Moscow Province

Background. The range of early-maturing cultivars suitable for the Non-Black-Earth Zone of the Russian Federation (RF) is extremely limited. The main method of finding sources of earliness for crop production and breeding is the evaluation of the gene pool under the required conditions.Materials and methods. The objects of the study were 81 soybean accessions from the VIR collection, precharacterized as early-ripening under the conditions of Northwest Russia. The studies were carried out in 2018–2020 as field trials under the conditions of Moscow Province.Results. Soybean accessions were characterized by the duration of the emergence-to-flowering (37–53 days), flowering-to-ripening (50–85 days) and emergence-to-ripening (81–130 days) periods. The extreme ripening dates for the accessions were observed from August 20 to October 5, while the maximum duration from emergence to ripening was from 93 to 139 days. The highest sum of active temperatures above 10°C for a growing season ranged from 1642 to 2189°C. Most of the studied accessions were characterized by a short emergence-to-flowering period. Therefore, the differences among accessions in the duration of the growing season were mainly due to the different lengths of their flowering-to-ripening period.Conclusion. Soybean seeds should ripen no later than the first 10 days of September for a stable harvest under the weather conditions of the Russian Non-Black-Earth Zone. There were 32 accessions from breeding centers of the RF, Belarus, Poland, Germany, Sweden, and the U.S. that met these requirements during the three years of observations. The selected accessions demonstrated a short emergence-to-flowering period of 37–48 days, and the length of their flowering-to-ripening period of 50–66 days, on average for three years. They can be used as sources of earliness in soybean breeding.

Soybean varietal response to irrigation and fertilization in the Lower Volga region

The research was conducted to study the responsiveness of soybean cultivars with different maturation periods to irrigation water and fertilizer and to select cultivars that provide high yields while saving water and agrochemical resources. The method of laying the field experiment was applied (B.A. Dospekhov, 1979). We used different cultivars of RRIIA breeding and doses of fertilizers designed to obtain a yield of 2.5 to 4.5 t/ha of grain. The plot area was 35 m2. The factorial experiment was conducted with four replications. An irrigation regime of 80 % FMC was achieved by watering 0.4 m layer of soil until budding phase and during ripening period - full ripeness. During the generative periods of development of agrophytocenosis (budding - filling of seeds in beans), the moisture inflow into the soil was increased to a depth of 0.6 m. The share of irrigation water increased significantly in years with hydrothermal coefficient GTC02 (2020) - up to 76.5 % - compared to more favorable years with GTC05 (2019). Early maturing cultivars were characterized by the lowest consumption of irrigation water per season: VNIIOZ 86 (31384014 m3/ha) and Volgogradka 2 (36534381 m3/ha), compared to mid-season cultivars VNIIOZ 31 and Volgogradka 3 (40785027 m3/ha). Cv. Volgogradka 2 had the greatest responsiveness to irrigation water - 3.57 t/ha and the lowest water consumption coefficient - 1136 m3/t of grain compared to other cultivars with indicators of 2.813.74 t/ha; 12351297 m3/t, respectively. For the first time, under irrigation in the Lower Volga region, the technology for obtaining high levels of grain yield of 2.974.27 t/ha was improved through the use of genotype of cultivar of regional breeding (Volgogradka 2, Volgogradka 3) and improved mineral nutrition of plants based on a programmed yield (2.54.5 t/ha).

Evaluating methane emissions from rice paddies: A study on the cultivar and transplanting date

Climate change, driven by increased greenhouse gas emissions, is a pressing environmental issue worldwide. Flooded rice paddy soils are a predominant source of methane (CH4) emissions, accounting for approximately 11 % of global emissions. Factors such as rice (Oryza sativa L.) cultivar, transplanting date, water management, and soil characteristics significantly influence these emissions. This study aimed to evaluate the CH4 emissions from rice paddies in relation to the cultivar and transplanting date. The experiment included two rice cultivars (an early-maturing cultivar, Unkwang, and a medium–late-maturing cultivar, Samkwang) and four transplanting dates (Times 1–4). In the present study, CH4 emissions were higher with earlier transplanting dates and decreased significantly with delayed transplanting. Weather conditions, such as cumulative mean air temperature, cumulative soil temperature, and total sunshine hours, were positively correlated with total CH4 emissions. The recommended regional transplanting date (Time 3) resulted in the highest rice grain yields for both cultivars. However, the earlier transplanting dates (Time 1 and Time 2) were more effective in improving plant growth characteristics such as rice straw weight, root biomass weight, and chlorophyll content. A significant positive correlation was observed between the root biomass weight of the rice and CH4 emissions in both cultivars, implying that an increase in root biomass weight led to an increase in CH4 emissions. Consequently, adhering to the advised regional transplanting dates is the most sensible approach for transplanting rice seedlings. This ensured lower CH4 emissions without compromising rice productivity or quality for both cultivars. Further research should focus on identifying the most appropriate rice-transplanting dates and management practices to effectively reduce CH4 emissions without compromising rice production.

Mitigation of Elevated CO2 Concentration on Warming-Induced Changes in Wheat Is Limited under Extreme Temperature during the Grain Filling Period

Elevated CO2 concentration (eCO2) generally increases plant growth by improving photosynthesis, but it is unclear whether eCO2 can alleviate the negative effects of elevated temperatures, especially in high-temperature years. Manipulative experiments with elevated [CO2] and temperature were conducted in North China to understand the effect of elevated CO2 concentration and temperature on wheat. The photosynthesis, An–PAR and A–Ci curve parameters, growth period, biomass, yield component, and yield of wheat were investigated under different [CO2] (around 400 and 600 ppm) and temperatures (ambient temperature and ambient temperature +2 °C) for 3 years by using controlled chambers. Results showed that elevated temperature significantly shortened the growth period and decreased the yield and biomass of wheat. Elevated [CO2] significantly increased the maximum net photosynthetic rate (Anmax) but reduced the maximum carboxylation rate (Vcmax) and the maximum electron transport rate (Jmax). The extremely high temperature during the grain filling period in 2019 exerted a serious negative impact on wheat production. Elevated [CO2] stimulated photosynthesis, increased kernel number per spike, and extended the duration of the grain filling period, which consequently increased biomass and grain yield under elevated temperatures in normal years (2018 and 2020). Although the combination of CO2 and temperature reduced photosynthesis and biomass, it also alleviated the negative impact of elevated temperatures on grain yield to some extent under extremely high temperature during the grain filling period in 2019. The mitigative effect of eCO2 under extreme high temperature is limited, and planting early-maturing cultivars or increasing the genotypes of kernel number per spike help to escape the extreme high temperature of the critical growth period.

An optimal combination of sowing date and cultivar could mitigate the impact of simultaneous heat and drought on rainfed wheat in arid regions

Drought and heat stress are the most important limiting factors for crop production. Simultaneous impacts of drought and heat stress during crop’s sensitive growth phases could be more harmful than their individual impacts. Accordingly, we investigated several management practices including 4 sowing dates, 3 cultivars in combination with 4 initial soil water contents to investigate the simultaneous impact of drought and heat stress on rainfed wheat grain yield in different climates (57 locations) across Iran from 1980 to 2016. A modified version of the wheat module of the Agricultural Production Systems sIMulator (APSIM) modelling framework was adopted. Historical temporal trends showed that grain yield has increased by + 10 kg ha-1 y-1 in cold regions and decreased by 14.5 kg ha-1 y-1 in mild and hot regions since 1980 for Azar-2 (as common cultivar). Long-term simulations indicated that grain yields of 3.3 t ha-1 could be obtained in rainfed agro-ecosystems under only-drought growth conditions. By adding the impact of heat stress, however, average grain yield further declined to 2.9 t ha-1 indicating a reduction of 0.4 t ha-1 owing to heat stress per se for the common cultivar. The results also showed that the long-term impact of drought and heat stress could be diminished with an optimal combination of sowing date, cultivar, and initial soil water depending upon climate classes. A combination of an early-maturity cultivar (“Azar-2”) with early sowing date (07-Oct) was recognized as the best management practice for cold and mild regions while the interaction of a mid-maturity cultivar (MMC), and an intermediate sowing date (20-Oct) was the best management practice for hot climates.

Effect of terminal bud clipping on growth and yield of soybean cultivars in the Pacific Northwest

AbstractSoybean [Glycine max (L.) Merr.] is one of the four major staple crops and the world's most important vegetable protein source. Very little information is available on the performance, yield, and cultivars of soybean when choosing a cultivar to grow in Pacific Northwest (PNW). Of the oilseed crops, soybean appears to have the best potential to be grown at a profit (high yields) in PNW when considering the high input costs for irrigated crops. The present study was conducted to determine if terminal bud clipping would increase yields of soybean cultivars under irrigated conditions in 2‐year field experiments. Five soybean cultivars were planted in four‐row plots with rows 0.13 m apart. Plots were replicated four times with two treatments (early clipping and late clipping) and control in a randomized complete block design. Data regarding yield and growth traits were recorded using standard procedure. Soybean yield was significantly influenced by the year of production and terminal bud clipping, whereas cultivars showed no effect. Early and late clipping resulted in a 15% and 18% increase in yields in 2018, whereas late clipping resulted in a 16% yield increase in 2019 compared to control. Terminal bud clipping resulted in shorter plants and reduced lowest pod height, lodging, and maturity compared with the control. Lodging and maturity decreased with late‐maturing cultivars. Finally, results suggest that terminal bud clipping increases soybean yields. Early maturing cultivars (maturity group 0.4) are unsuitable for PNW due to the lowest pod height.

Relationship between Satsuma mandarin yield and meteorological factors in Shizuoka and distribution of alternative flowering indices in Mikkabi production area, Japan.

Biennial bearing, the biggest factor destabilizing citrus fruit production, is primarily attributed to unfavorable weather changes. However, the relationship between the yield of Satsuma mandarin for more than 50 years and the weather remains poorly understood. Therefore, the present study investigated the effect of meteorological factors, such as average temperature, precipitation, and sunshine duration, on the yield of Satsuma mandarin in Shizuoka Prefecture, Japan. We analyzed fruit production statistics and meteorological observation data from 1961 to 2018. Furthermore, we investigated the alternative indices of flowering and sprouting in each of the 20 districts of Mikkabi Town, Hamamatsu City, Shizuoka Prefecture. We detected a positive correlation between the average temperatures in March and February and yields in Shizuoka and Hamamatsu Cities. All alternative indices, except flowering in the early-maturing cultivar, were significantly lower in the southern than in the northern districts (P < 0.01 or 0.05). Particularly, the alternative index of flowering in the late-maturing cultivar was significantly different between the northern and southern districts (P < 0.01). Furthermore, we found a negative correlation between the mean annual temperature or average temperature from January to April and alternative indices of flowering and sprouting. The findings of our field survey in Mikkabi production area suggest that mean annual temperature may affect the biennial bearing of Satsuma mandarin. © 2023 Society of Chemical Industry.

Early–maturing cultivar of winter wheat is more adaptable to elevated [CO2] and rising temperature in the eastern Loess Plateau

Understanding the impacts of rising temperature and elevated [CO2] on different crop cultivars is critical to devising agronomic strategies and cultivar selection in the context of climate change adaptation. The growth period, biomass, and yield of two wheat cultivars (early– vs. late–maturing) were simulated by the Agricultural Production Systems sIMulator (APSIM) validated with pot experiments under the scenarios of elevated [CO2] and 2 °C warming based on the baseline climate for 1961–2016 at Taigu in North China. We also investigated the effects of extreme high temperature on the yield and yield components of these wheat cultivars. We found that APSIM well simulated the changes in the growth period, leaf area index (LAI), biomass, and yield induced by 2 °C warming and elevated [CO2]. Long–term simulations showed that 2 °C warming decreased the growing period between sowing and jointing for both cultivars. 2 °C warming and elevated [CO2] affected the wheat yield mainly by altering the grain numbers. Extreme high temperature decreased the grain numbers and yield of the late–maturing cultivar but not the early–maturing one. The findings suggest that early–maturing cultivar would be better adapted to elevated [CO2] and rising temperature than the late–maturing one in the eastern Loess Plateau.

Flowering responses of serradella (Ornithopus spp.) and subterranean clover (Trifolium subterraneum L.) to vernalisation and photoperiod and their role in maturity type determination and flowering date stability

Context Serradellas (Ornithopus spp.) are promising alternative annual legumes to subterranean clover (Trifolium subterraneum L.), for permanent, temperate pastures. However, many cultivars exhibit unstable flowering dates across years. This is a risk for seed production and persistence. Aim This study assessed how vernalisation and photoperiod cues determine maturity type and flowering date stability among serradella cultivars. Methods First flower appearance was recorded for early and late maturing cultivars of yellow serradella (Ornithopus compressus L.), French serradella (Ornithopus sativus Brot.) and subterranean clover after exposure to six vernalisation treatments (0, 1, 3, 5, 7 or 9 weeks at 5°C) with subsequent growth under four photoperiods (8, 12, 16 or 20 h). Key results ‘Intrinsic earliness’ differed by only zero to three nodes for cultivars within species, indicating that maturity type was determined primarily by a cultivar’s responses to vernalisation and photoperiod. An interaction between these responses was observed, with a precipitous decline in the requirement for vernalisation when photoperiods exceeded 12 h. Many cultivars also displayed a persistent component to their vernalisation response, whereby long photoperiods (20 h) did not completely negate the response to vernalisation. Conclusions Later maturity was associated particularly with need for long exposure to the vernalisation treatment to minimise the duration from sowing to first flower appearance. Stable flowering is more likely when a cultivar has components of its vernalisation requirement that are not satisfied before autumn ends to prevent premature flowering, and a photoperiod response in spring that overrides any unmet vernalisation requirement. Implications Persistence by serradella cultivars requires selection for suitable responsiveness to vernalisation and photoperiod.

Plant genetics: Mechanisms of wild soybean adaptation

A new study shows that natural variation in the flowering repressor E1-like-a (Tof4/E1La) promoted wild soybean adaptation to high latitudes. This lost early-flowering allele can be reintroduced into cultivated soybean for developing early-maturing cultivars.

Nitrogen fertilization can mitigate cotton yield loss by temporary shading at early flowering

Cotton (Gossypium hirsutum L.) yield is decreased under low radiation, but there are few reports on possible interactions of N fertilizer application and light limitation on cotton production. The objective of this work was to evaluate growth, yield components, and boll distribution in cotton as affected by N rates under light restriction. Three experiments were conducted for two years in Central (Primavera do Leste and Chapadão do Sul) and Southeastern (Itapeva) Brazil. Cotton plants were shaded at early flowering to a 42 % reduction in global radiation for 16–25 days. Four N rates were used in Primavera do Leste and Itapeva; and three N rates and two genotypes, an early- (FM 906GLT) and a late-maturing (FM 983GLT) cultivar, were used in Chapadão do Sul. Shading decreased lint yield by 10 % in Primavera do Leste and by 12 % in Chapadão due to 24 % and 32 % reduction in boll number at the lower third of the plant, respectively. In Itapeva, the number of bolls at the lower fruiting branches was decreased 19% by shading, but a 10% lint yield reduction was observed only with 35 kg ha−1 of N. As to the main effects, lint yield and number of bolls increased with N rates up to 155, 142 and 105 kg ha−1, depending on the site. Lint yield of shaded plants was more responsive to higher N rates, which also increased plant height, number of bolls and the main stem node number of the last fruiting branch. Cotton cultivars had similar lint yields despite differences in boll distribution. At lower fruiting branches, the early-maturing cultivar showed an average boll number 59 % higher, but the late one produced 81 % and 63 % more bolls on the upper branches at 105 and 185 kg ha−1 of N, respectively. We concluded that N-deficiency inhibited the recovery of cotton from losses caused by shading, whereas a high-N availability minimizes damages after shading during blooming.

A daylength-neutral winged bean (Psophocarpus tetragonolobus) for Southern Australian latitudes

Abstract. Eagleton GE. 2022. A daylength-neutral winged bean (Psophocarpus tetragonolobus) for Southern Australian latitudes. Asian J Agric 6: 68-78. In the summer of 2019, on the central coast of NSW, Australia (at Latitude 34°S), an early-maturing genotype of the tropical legume crop, winged bean (Psophocarpus tetragonolobus (L.) DC.), was detected among a range of late-maturing accessions. The performance of this accession, MY0-01 from Bago in Myanmar, was evaluated in staked plots alongside one other accession from Myanmar and two from the island of New Guinea planted on three successive occasions between October and late November 2020 in a split-plot experiment. Across the three planting dates, the mean number of days from planting to the first open flower for MYO-01 ranged from 68 to 82 + s.e. 3.2 compared with a range of 119 to 167 for the other three accessions. The mean accumulated seed yield of MYO-01 obtained from the October planting equated to 3.1 t ha-1, but by the third planting in late November, the yield was only half as much. Among the four accessions, MYO-01 was second in the amount of lower stem branching and tuber yield, with the smallest pods and hardest seeds. Hard seededness creates difficulties for germination and plant establishment and is a limitation in MYO-01, as are its small pods, which lowers its potential for vegetable production. Investigating genetic control of photoperiod insensitivity in MYO-01 and combining the ability for pod and seed characteristics is relevant to sub-tropical latitudes and for developing stable early maturity cultivars for the tropics.