Large-seeded Cultivars Research Articles

DNA methylation-mediated ROS production contributes to seed abortion in litchi

Although there is increasing evidence suggesting that DNA methylation regulates seed development, the underlying mechanisms remain poorly understood. Therefore, we aimed to shed light on this by conducting whole-genome bisulfite sequencing using seeds from the large-seeded cultivar 'HZ' and the abortive-seeded cultivar 'NMC'. Our analysis revealed that the 'HZ' seeds exhibited a hypermethylation level compared to the 'NMC' seeds. Furthermore, we found that the genes associated with differentially methylated regions (DMRs) and differentially expressed genes (DEGs) were mainly enriched in the reactive oxygen species (ROS) metabolic pathway. To investigate this further, we conducted nitroblue tetrazolium (NBT) and 2,7-Dichlorodihydrofluorescein (DCF) staining, which demonstrated a significantly higher amount of ROS in the 'NMC' seeds compared to the 'HZ' seeds. Moreover, we identified that the gene LcGPX6, involved in ROS scavenging, exhibited hypermethylation levels and parallelly lower expression levels in 'NMC' seeds compared to 'HZ' seeds. Interestingly, the ectopic expression of LcGPX6 in Arabidopsis enhanced ROS scavenging and resulted in lower seed production. Together, we suggest that DNA methylation-mediated ROS production plays a significant role in seed development in litchi, during which hypermethylation levels of LcGPX6 might repress its expression, resulting in the accumulation of excessive ROS and ultimately leading to seed abortion.

Nitrogen application in pod zone improves yield and quality of two peanut cultivars by modulating nitrogen accumulation and metabolism

Cultivated peanut (Arachis hypogaea L.) represents one of the most important oil and cash crops world-widely. Unlike many other legumes, peanuts absorb nitrogen through their underground pods. Despite this unique feature, the relationship between yield and nitrogen uptake within the pod zone remains poorly understood. In our pot experiment, we divided the underground peanut part into two zones—pod and root—and investigated the physiological and agronomic traits of two peanut cultivars, SH11 (large seeds, LS) and HY23 (small seeds, SS), at 10 (S1), 20 (S2), and 30 (S3) days after gynophores penetrated the soil, with nitrogen application in the pod zone. Results indicated that nitrogen application increased pod yield, kernel protein content, and nitrogen accumulation in plants. For both LS and SS peanut cultivars, optimal nitrogen content was 60 kg·hm− 2, leading to maximum yield. LS cultivar exhibited higher yield and nitrogen accumulation increases than SS cultivar. Nitrogen application up-regulated the expression of nitrogen metabolism-related genes in the pod, including nitrate reductase (NR), nitrite reductase (NIR), glutamine synthetase (GS), glutamate synthase (NADH-GOGAT), ATP binding cassette (ABC), and nitrate transporter (NRT2). Additionally, nitrogen application increased enzyme activity in the pod, including NR, GS, and GOGAT, consistent with gene expression levels. These nitrogen metabolism traits exhibited higher up-regulations in the large-seeded cultivar than in the small-seeded one and showed a significant correlation with yield in the large-seeded cultivar at S2 and S3. Our findings offer a scientific basis for the judicious application and efficient utilization of nitrogen fertilization in peanuts, laying the groundwork for further elucidating the molecular mechanisms of peanut nitrogen utilization.

The trait-specific collection of large-seeded sunflower at VIR: ba source for breeding cultivars and hybrids

Background. In recent years, an increase has been observed in the share of sunflower seeds in the confectionery and food industries. There are 30 cultivars and only 3 hybrids for confectionery use among 839 zoned sunflower cultivars and hybrids listed in the State Register for Selection Achievements Admitted for Usage in 2023. Thus, the development of source material for breeding large-seeded cultivars and hybrids remains a relevant task.Materials and methods. The studied material included 90 accessions selected for their large seed size from VIR’s sunflower collection. The following characters were assessed: 1000 seed weight, days from sprouting to maturation, plant height, head diameter, cypsela color and size, and resistance to downy mildew. DNA markers were used to identify accessions with the Rf1 gene and CMS.Results. Accessions k-2818 (Primorsky Territory), k-3633, k-3748, k-3782 (China), and k-3578 (Ukraine) were the best in 1000 seed weight. Russian cvs. ‘Alekseyevsky Krupnoplodny 2’ (k-3552), ‘Gyar-Gyar’ (k-1589), ‘SPK’ (k-3426), and ‘Lakomka’ (k-3526) confirmed their large seed size. The sterile type of cytoplasm was identified in 12 accessions. Fourteen accessions with fertile cytoplasm had diagnostic markers of the nuclear Rf1 gene.Conclusion. The large-seeded cultivars developed at VNIIMK, ‘SPK’, ‘Lakomka’, and k-3782 from China were the best not only in their large seed size but also in downy mildew resistance. As a result of long-term studies, a trait-specific collection was established for the large seed size trait. It included 90 accessions that can be used in the development of confectionery cultivars. Large-seeded sunflower accessions carrying the Rf1 gene were identified. Some of them became the ancestors of donor lines for both pollen fertility restoration genes and large seed size.

Перекрёстная гербицидоустойчивость к трибенурон-метилу и имидазолинонам у подсолнечника

Herbicide cross-resistance studies were conducted in the field in 2021 and 2022. We studied the Surus hybrid and the large-seeded cultivar Consul, homozy-gous for the gene of resistance to tribenuron-methyl Sur, as well as the large-seeded cultivar Aladdin, ho-mozygous for the gene of resistance to imidazoli-nones Imr. The large-seeded cultivar Caravan was the standard for herbicide susceptibility. Herbicides Ex-press (tribenuron-methyl) and Euro-Lightning (imazamox, imazapyr) were used. Plants were treated with herbicide in the phase of three pairs of leaves using a backpack sprayer. The degree of plant damage was assessed on the 10th day after treatment using a 9-point scale of phytotoxicity. The presence of susceptible, but not dead plants with leaf morphoses, in an amount of up to 16% when treated with Euro-Lightning sulfonylurea-resistant hybrid Surus and variety Consul indicates their partial cross-resistance to imidazolinones. The presence of susceptible, but not dead plants with leaf morphoses, in an amount of up to 35%, when the imidazolinone-resistant cultivar Aladdin is treated with Express indicates its partial cross-resistance to tribenuron-methyl. Morphological anomalies in the growth and development of susceptible but not dead plants, which are intermediate points of 4-6 on the phytotoxicity scale, make biologically surviving plants unpromising from a breeding point of view.

Managing dryland wheat to produce high-quality grain

The properties of individual grain weight, protein concentration and protein composition contribute to grain quality of wheat. They are known to be affected by genetics, environment and crop management. This paper reports these properties in two dryland field experiments comparing cultivars with similar yield but with contrasting grain weight and number. A large-seeded cultivar, Baviacora, and a small-seeded cultivar, H45, were managed with different nitrogen (N) fertilizer applications and grown in seasons with different rainfall. The aim is to suggest strategies to produce wheat grain of consistently high quality for specified markets, with either pre-harvest or post-harvest management. Individual grain weight and protein concentration varied throughout the spikes of the cultivars and responded to crop management and environment. Protein concentration within a spike was closely correlated with individual grain weight, increasing by 0.05 ± 0.006% per mg of additional grain weight, independent of cultivar or position of grains on the spike. Grain protein composition was related to protein concentration of individual grains but was not as sensitive to individual grain weight. Larger grains were associated with less glutenin per unit of protein, partly offsetting the increase in protein concentration with grain weight. Unextracted polymeric protein (%UPP) was unrelated to grain weight but was negatively related to grain protein concentration in Baviacora. If found to be general, the within-spike relationships between individual grain weight, and the concentrations of grain protein, glutenin and %UPP offer promise for improving grain segregation and post-harvest processing to produce grain of closely defined quality from an unprocessed harvest sample. • Grain protein amount and composition varied with genotype, environment and management. • Within spikes, protein concentration was positively correlated with grain weight. • Glutenin concentration varied with protein concentration of individual grains.

Cotton Emergence and Yield Response to Planter Depth and Downforce Settings in Different Soil Moisture Conditions

US cotton producers are motivated to optimize planter performance to ensure timely and uniform stand establishment early in the season, especially when planting in sub-optimal field conditions. Field studies were conducted in 2017, 2018 and 2019 to evaluate the effect of seeding depth and planter downforce on crop emergence and yield in cotton planted in different soil moisture conditions. Field conditions representative of dry, normal and wet soil moisture conditions were attained by applying 0, 1.27 and 2.54 cm of irrigation within the same field. Two cotton cultivars (representing a small-seeded and a large-seeded cultivar, 9259–10,582 and 11,244–14,330 seeds kg−1, respectively), were planted at seeding depths of 1.3, 2.5 and 3.8 cm with each seeding depth paired with three different planter downforces of 0, 445 and 890 N in each block. Cotton was planted in plots that measured 3.66 m (four-rows) wide by 10.67 m long. Results indicated that crop emergence was affected by the seeding depth across most field conditions and higher crop emergence was observed in the large-seeded cultivar at 1.3 and 3.8 cm seeding depths in dry and wet field conditions, respectively. Lint yield was also higher for the large-seeded cultivar at the 3.8 cm seeding depth across all field conditions in 2017, and in dry field conditions in 2018. Planter downforce effect on crop emergence varied among the cultivars where the large-seeded cultivar exhibited higher crop emergence than the small-seeded cultivar at 445 and 890 N downforce. Planter downforce of 445 N yielded greater than the 0 and 890 N treatment in dry field conditions in 2017. The study results suggest that matching planter depth and downforce settings for prevalent soil moisture conditions at planting along with appropriate cultivar selection can help in achieving optimal emergence and yield in cotton.

Combinative breeding for large seeds in soybean

Technological qualities of the seeds, including their mass, play an important role in the purposeful use of soybean for food production. The purpose of this study is to determine the potential of specific crosses and recombinant lines in the combinative breeding of high yielding large-seeded soybean varieties. During the period of 2018-2019 the F3 and F4 hybride generations of crosses with participation of the ultra-early mature and large-seeded cultivar Romantica were studied. Data were used to evaluate: presence and extent of positive transgressive forms by absolute seed mass in F3 family crosses; genotypic diversity and additive variance at specific crosses; the effectiveness of selection of the trait large seed in F3. According to the results, transgressive selection can be successfully used to reach the goal large seeds in soybean. The efficiency of selection of transgressive forms in F3 generation is high. The genetic potential to combine a high specific mass of seeds with a high yield of seeds per plant has been established for the Romantica cross with the Bulgarian standard variety Srebrina. Recombinant lines suitable for intensive selection for the trait lage seed were obtained from the ‘Romantica’ x ‘Oria’ combination. The ‘Saikai 20’ x ‘Romantica’ cross possess a very high degree of transgressive segregations.

Influence of Seeding Rate, Planter Downforce and Cultivar on Crop Emergence and Yield in Singulated and Hill-Dropped Cotton

Cotton (Gossypium hirsutum L.) growers are motivated to reduce seeding rates due to increased technology fees associated with improved transgenic cotton cultivars. Advances in planting machinery have improved precision of seed metering and seed placement in recent years. A two-year study was conducted to evaluate the effect of seeding rate, planter downforce, and cultivar on crop emergence and lint yield in cotton planted as singulated and hill-drop (two seed hill-1) configuration. Study treatments consisted of two seeding rates (71,660 and 107,490 seed ha-1), two to three planter downforces (0, 445 and 890 N in 2017; 0 and 890 N in 2018) and two cotton cultivars (representing a large-seeded and small-seeded cultivar, 9,259 - 10,582 and 11,244 - 14,330 seed kg-1, respectively) arranged in a strip-split plot design in both seeding configurations. Crop emergence and lint yield in the middle two rows (four-row plots) were measured to evaluate treatment effects among seeding configurations. Results showed that seeding rate and cultivar did not affect (p>0.05) crop emergence and lint yield in both singulated and hill-drop cotton. Crop emergence varied between the two years due to differences in field tillage conditions. Planter downforce affected crop emergence in singulated cotton but not in hill-drop cotton during both years. Field tillage conditions also influenced downforce effect on crop emergence. Selection of an optimal planter downforce had more significant effect (p<0.05) on singulated cotton than hill-dropped cotton. Results showed that large-seeded cultivars can be utilized to attain a high crop emergence early in the season which can help in minimizing production risks associated with poor stand establishment. High seed and technology fees incurred by growers can be effectively reduced by planting lower seeding rates - given an adequate stand establishment is attained using appropriate planter setup including downforce and cultivar selection.

Inheritance of seed size by hybrid populations of pea (F1, F2)

Pea (Pisum sativum L.) is one of the ancient and valuable high-protein leguminous cultures in the world. Breeding of new high-yielding cultivars is the main reserve to increase production of pea seeds. At the present time, intraspecific hybridization has a great importance in selection of new cultivars of pea. However, consistent patterns of inheritance of a number of economically valuable traits by hybrids are still insufficiently investigated. The objective of this research work was to study inheritance of seed size (1000-kernel weight) by pea hybrids of the first and second filial generations (F1, F2). The crossing and back-crossing (reciprocal crossing) were conducted. In our experiments, the first filial generation hybrids (F1) had a lower 1000-kernel weight than the large-seeded parental cultivars. Herewith the large-seeded genotype of the female parental cultivar had more influence on displaying of this trait in hybrids than of the male parental cultivar. In the second filial generation hybrids (F2) showed intermediate inheritance of seed size. The results of our experiments attest high efficiency of seed size selection in segregating generations of hybrids, obtained from crosses between cultivars carrying genes of seed size.

Genome-wide discovery of DNA polymorphisms among chickpea cultivars with contrasting seed size/weight and their functional relevance

Seed size/weight is a major agronomic trait which determine crop productivity in legumes. To understand the genetic basis of seed size determination, we sought to identify DNA polymorphisms between two small (Himchana 1 and Pusa 362) and two large-seeded (JGK 3 and PG 0515) chickpea cultivars via whole genome resequencing. We identified a total of 75535 single nucleotide polymorphisms (SNPs), 6486 insertions and deletions (InDels), 1938 multi-nucleotide polymorphisms (MNPs) and 5025 complex variants between the two small and two large-seeded chickpea cultivars. Our analysis revealed 814, 244 and 72 seed-specific genes harboring DNA polymorphisms in promoter or non-synonymous and large-effect DNA polymorphisms, respectively. Gene ontology analysis revealed enrichment of cell growth and division related terms in these genes. Among them, at least 22 genes associated with quantitative trait loci, and those involved in cell growth and division and encoding transcription factors harbored promoter and/or large-effect/non-synonymous DNA polymorphisms. These also showed higher expression at late-embryogenesis and/or mid-maturation stages of seed development in the large-seeded cultivar, suggesting their role in seed size/weight determination in chickpea. Altogether, this study provided a valuable resource for large-scale genotyping applications and a few putative candidate genes that might play crucial role in governing seed size/weight in chickpea.

Identification and dissection of single seed weight QTLs by analysis of seed yield components in soybean.

Single seed weight (SSW), or seed size, is a seed yield components (SYC) in soybean, and it is suggested that the genetic factors regulating SSW are involved in the control of other SYCs. The quantitative trait loci (QTLs) for SSW and their effects on the other SYCs were investigated using a recombinant inbred line population derived from typical small- and large-seeded cultivars that were cultivated in two different environments. QTL analysis detected four environmentally stable QTLs for SSW, two of which coincided with the defined loci, qSw17-1 and Ln. The effects of the other loci, qSw12-1 and qSw13-1, were confirmed by analyzing residual heterozygous line progenies derived from the recombinant population. These four QTL regions were also involved in the control of an additional SYC, namely the large-seeded allele at each locus that reduced either the number of pods per plant or the number of ovules per pod. These results suggest the presence of at least two different regulatory mechanisms for SSW. Isolation of genes responsible for these QTLs provides an important tool in the understanding and utilization of SSW diversity for soybean breeding.

Characterization of soybean genotypes for Asian soybean rust reaction under screen house condition

Inayati A, Yusnawan E. 2016. Characterization of soybean genotypes for Asian soybean rust reaction under screen house condition. Biodiversitas 17: 609-613. Asian soybean rust (ASR) caused by Phakopsora pachyrhizi is one of the major diseases limiting soybean yield. This disease has widely spread on soybean crops in Indonesia. The use of resistant cultivars is one of the economical approaches to control ASR. The objectives of this study were to assess the resistance of soybean lines derived from crossing two largeseeded cultivars (Baluran and Grobogan) with a broad adaptive cultivar (Kaba) and to identify resistant genotype characteristics under screen house conditions. All genotypes were artificially inoculated with P. pachyrhizi uredospores. Number of pustules per leaf, the development of ASR, and yield components including number of intact pods per plant, number of empty pods, and weight of pods per plant were observed. Thirteen lines of Baluran pedigrees had higher resistant response to ASR compared to Grobogan pedigrees. Fewer numbers of pustules (8 pustules cm-2), lower value of area under the disease progress curve (AUDPC), and redish brown (RB) lesion type were observed in resistant lines. In contrast, susceptible lines had more pustules (> 21 pustules cm-2), higher AUDPC value, and had mixed lesion type (RB and Tan). ASR reduced seed size and yield. The average weight of 100 seeds of resistant lines was 10.2 g while on susceptible lines, the 100-seed weight ranged from 8.7 to 12.6 g. The average yield per plant varied from 2.7 to 6.1 g.Baluran/Grobogan pedigrees were more susceptible to ASR than Baluran/Kaba pedigrees, however, those pedigrees showed better yield per plant and were supposedly more tolerant to ASR.

Controlling indeterminacy in short season lentil by cultivar choice and nitrogen management

Western Canada is a major area of lentil (Lens culinaris Medik.) production and global export, specializing in short season production. In cool or wet years lentil often fails to mature within the 115-d growing season. In the absence of a determinate cultivar, our goal was to test whether current cultivars could mature earlier and without a yield penalty by managing N fertility practices. Eight cultivars of lentil were grown in Saskatchewan during 2006 and 2007 under three N fertility treatments: 50kgNha−1, Rhizobium inoculant, and an uninoculated control. Measurements included days to maturity, yield, aboveground biomass (DW), plant total N content, and N2 fixation. Lentil yielded 1900kgha−1, 2120kgha−1 and 2070kgha−1 in control, fertilized, and inoculated treatments, respectively. The N treatments did not affect days to maturity or harvest index (HI). Yield and N2 fixation were unaffected by the N treatments except in drought, where yield was smallest in the control and N2 fixation was smallest in the fertilized treatment. Cultivars CDC Milestone, CDC Red Rider and CDC Rouleau had comparable yield and matured earlier than large-seeded cultivars, demonstrating that growing a recently released small-seeded cultivar gave earlier maturity than N fertility management. Results did not demonstrate any advantage from applying N fertilizer to hasten maturity, to increase HI or yield compared to the current practice of relying on N2 fixation from proper inoculation. Biological N2 fixation is a sustainable and more economical means of supplying N to the lentil crop without the need to apply N fertilizer, particularly with high yielding early maturing cultivars.

Endogenous hormones in seed, leaf, and pod wall and their relationship to seed filling in soybeans

In order to investigate the possible relationship between endogenous hormones and seed filling in soybeans, concentrations of abscisic acid (ABA), gibberellins (GA3), indole-3-acetic acid (IAA), and cytokinins (ZR) in seed, leaf, and pod wall were determined during seed filling of 3 soybean cultivars differing in seed size and quality. All cultivars were grown at 3 densities. The large-seeded cultivar had a strong and greater ability to accumulate photosynthate during seed filling. The genetic trait of seed size was fully expressed at low density. The large-seeded cultivar had a much higher ABA concentration in seed than the moderate and small-seeded cultivars before physiological maturity. ABA concentration in the large-seeded cultivar seed was 40% greater than that of the small-seeded cultivar at 30 days after flowering. Higher densities increased ABA concentrations in seeds. Two peaks of seed GA3 concentration were observed during seed filling. GA3 concentrations at all densities were similar. The peaks of IAA concentration in the 3 cultivars uniformly occurred at 50 days after flowering. The large-seeded cultivar had greater peak concentrations of GA3 and IAA in seed than the other cultivars, while the peak concentration of ZR was highest in the small-seeded cultivar. The concentrations of ABA in leaf increased with time while that of GA3 decreased. The large-seeded cultivar had higher ABA and IAA concentration in leaf while the small-seeded cultivar consistently had higher GA3 concentration in leaf. ZR was present in a smaller amount in the leaf, and was not detected in the pod wall. The large-seeded cultivar maintained higher IAA concentration in pod wall. ABA concentration in seed was positively correlated with seed-filling rate (P < 0.01, r = 0.85**, 0.92**, and 0.83** for large-, moderate- and small-seeded cultivars respectively).The concentration of GA3 in seed was significantly correlated with the seed-filling rate in large- and moderate-seeded cultivars (P < 0.01, r = 0.87**; P < 0.05, r = 0.63*), and no correlation was found for the small-seeded cultivar. There was no correlation between the concentrations of seed IAA, ZR, and seed-filling rate. There was a parallel relationship between seed growth and leaf/pod wall ABA concentration. Thus, ABA might offer a driving force for photosynthate phloem unloading in the seed coat. Lower concentration of ABA and GA3 in the leaf than in seed suggests that most of the two hormones is transported to seed. The mechanism of IAA in seed growth and GA3 concentration and its dynamic in seed quality need further investigation.

Relationship between bruchid resistance and seed mass in mungbean based on QTL analysis

Bruchids (Coleoptera: Bruchidae) can cause serious damage to mungbean and several other leguminous crops and there is a strong association between small seed size and bruchid resistance. In investigating the feasibility of breeding large-seeded cultivars with high levels of bruchid resistance, we studied the relationship between these two traits by QTL analysis. A major locus conferring resistance to Callosobruchus chinensis was identified from a wild mungbean genotype, 'ACC41' (belonging to Vigna radiata var. sublobata), collected in Australia. The proportion of the C. chinensis resistance response that could be attributed to this single QTL varied among four different resistance assays. The highest value reached was 98.5%, suggesting that bruchid resistance in this genotype is likely conditioned by this single locus. The QTL was robust and its detection was not affected by the use of different sources of the insect, different lengths and conditions of seed storage, or different bruchid resistance assay methods. This bruchid resistance QTL was coincident with one of the loci conferring seed mass detected from the three seed sources produced in Australia. However, such a co-location was not detected for the seed source produced in China. Covariance analysis revealed a complex relationship between seed mass and bruchid resistance. Nevertheless, the effect of the bruchid resistance QTL remained highly significant for all four assays after the effect of seed mass was accounted for. These results, together with the relationship between the bruchid resistance QTL identified in this study and a second one detected previously in a wild mungbean genotype from Madagascar, are discussed.

Pod and seed numbers as a function of photothermal quotient during the seed set period of field pea ( Pisum sativum) crops

The effects of radiation and temperature during the seed set period (SSP) on pod number per square metre (PN m −2) and seed number per square metre (SN m −2) and those of temperature during grain filling on unit seed weight (USW, milligram per seed) of field pea ( Pisum sativum L.) were examined in experiments involving irrigated crops of three or more cultivars of contrasting maturity sown on two or more dates per year from 1996 to 1998 at Buenos Aires, Argentina. The duration of the seed-setting phase was estimated from records of the progress of flowering on the main stem and an estimate (obtained using an optimisation procedure) of the thermal time from flowering at which the uppermost reproductive node reached the final stage of seed abortion (FSSA). The FSSA at a particular node was assumed to be achieved 200 °C day ( T b=4 °C) after flowering at the same node. The grain-filling phase was assumed to run from the achievement of FSSA at the first reproductive node through to 200 °C day ( T b=0 °C) after the date of achievement of the FSSA by the second flowering node. The treatments (cultivar, sowing date, year) produced important ranges of above-ground biomass (AGB) at maturity (271–782 g m −2), seed yield (SY, 119–331 g m −2), SN (1062–3698 seeds m −2) and USW (67–150 mg seed −1). Seed yield was strongly correlated with SN, and there was full compensation between SN and USW in large-seeded cultivars in the high SN range, but not at lower values of SN or in small-seeded cultivars. Both PN ( r=0.83) and SN ( r=0.87, P<0.0005) were strongly correlated with the mean daily value of the photothermal quotient (PQ=incident radiation/(mean temperature − base temperature)) for the seed-setting phase. Large- and small-seeded cultivars had PN/PQ and SN/PQ relationships with slopes which did not differ among categories but with significantly different intercepts. When the effects of low temperatures during flowering and early grain growth were allowed for, outliers on the PN/PQ and SN/PQ relationships for unstressed crops fell within the confidence limits of the respective linear regressions. Unit seed weight showed a negative response to mean temperature during the grain-filling phase in large- and small-seeded cultivars. We conclude that the relationships established in these experiments, taken together with previous work by other authors, constitute a robust basis for modelling the yield of unstressed field pea crops.

CARNAVAL - Common bean cultivar

Carnaval is an early (65 to 85 days) large-seeded determinate growth habit common bean cultivar released for sowing in Minas Gerais State. It belongs to the Cranberry class, with broad adaptation and resistance to lodging, and shows high yield potential. It is resistant to fusarium wilt; moderately resistant to anthracnose, rust, and common bacterial blight; and it is moderately suscetible to angular leaf spot, alternaria leaf spot, and powdery mildew.

Evaluación agronómica y parámetros genéticos en soya para consumo humano directo en Puerto Rico

En las regiones tropicales del hemisferio occidental, el alto contenido de proteína de la soya [Glycine max (L.) Merrill] puede mejorar la dieta de la población. Para este propósito, sería necesario desarrollar cultivares adaptados a la región y con semillas de tamaño adecuado para consumo humano. Los objetivos del estudio fueron estimar la heredabilidad de algunas características agronómicas, las correlaciones genéticas y fenotípicas entre ellas y la comparación de las características agronómicas y reproductivas de las líneas, sembradas en distintas fechas en Puerto Rico. En diciembre de 1992 se evaluaron 89 plantas individuales F4:5 del cruzamiento de IAC-8 [Grupo de Madurez (GM) IX, no adaptado para consumo humano, con semilla de tamaño mediano] x Kanto-101 (GM III, adaptado para consumo humano, con semilla de tamaño grande), los padres y líneas controles. Las líneasF4:6 se evaluaron en ensayos replicados en junio y agosto de 1993. Las características consideradas fueron fecha de la floración completa (R2), fecha del llenado de las vainas (R6), fecha de la madurez completa (R8), altura de las plantas, ancho de las vainas y peso de 100 semillas. Las heredabilidades expresadas a base del promedio de las líneas fueron de intermedias (0.56) a altas (0.96). Las correlaciones fenotípicas y genotípicas variaron de cero a altas (0.96). Las correlaciones de rango fueron intermedias, positivas y significativas, variando desde 0.41 a 0.79. Para todas las características, los genotipos que fueron seleccionados en el 10% superior durante las siembras de junio y agosto, a base del promedio de las líneas, también fueron seleccionados en diciembre, a base de las medidas en plantas individuales. En el trópico, la selección de genotipos de soya con tamaño de semilla adecuado para consumo humano directo se puede realizar en distintas épocas de siembra durante el mismo año, en plantas individuales en las etapas iniciales del programa y en ensayos replicados posteriormente.

Optimum plant density of desi chickpea (Cicer arietinum L.) increases with increasing yield potential in south-western Australia

The response of chickpea (cv. Tyson) seed yield to sowing rate (30–180 kg/ha) was examined in 18 field experiments across 3 years in south-western Australia. The economic optimum plant density was estimated at each site by fitting an asymptotic model to the data and calculating the point where the cost of extra seed equalled the return from additional seed yield, allowing a 10% opportunity cost for the extra investment. When averaged across all sites and seasons, plant densities varied from 14 plants/m2 when sown at 30 kg/ha to 84 plants/m2 when sown at 180 kg/ha. Therefore, only about 54% of seeds sown established into viable plants, even though the germination test of the seed was about 80%. The poor establishment rate is thought to be mainly due to physical damage to the seed during transport and sowing, as well as unfavourable seed-bed moisture and temperature conditions. At most experimental sites the seed yield of desi chickpea responded positively to an increase in sowing rate up to about 120 kg/ha. Increased yields at high sowing rate can be directly attributed to large plant populations. Although in many cases the number of pods per plant, seed size, and harvest index were reduced at high plant populations, increased plant density compensated for these effects and seed yield tended to increase. There was a good relationship between economic optimum plant density and yield potential derived in this study (r2 = 0.497, P&lt; 0.001) and this improves the ability of desi chickpea producers to select the most profitable sowing rate, depending upon their yield potential. These results suggest that the optimum plant density is 50 plants/m2 for most chickpea crops in south-western Australia yielding about 1.0 t/ha, whereas in high-yielding situations (&gt;1.5 t/ha), plant densities &gt;70 plants/m2 produce the most profit. Although not observed in these experiments, high plant densities can exacerbate fungal diseases, and hence, reduced plant densities are desirable in disease-prone situations. Differences in sowing rate responses may be expected between Tyson and new large-seeded cultivars such as Heera and Sona, which have longer branches and more open canopy, or kabuli types, and this deserves further investigation.

Seed size and seed growth rate in relation to cotyledon cell volume and number in common bean

Seed yield is negatively associated with cultivar seed size in common bean ( Phaseolus vulgaris L.). Large-seeded cultivars are predominantly from the Andean center of origin while small-seeded cultivars are from the Mesoamerican center. The objective of this study was to determine the relationship of cotyledon cell number and individual cell volume to seed size and seed growth rate (SGR) in common bean, and to examine the basis for a previously reported decline in seed size and SGR for large-seeded Andean lines when grown in warm environments. Crop growth analyses were conducted with 16 lines of common bean in Palmira (965 m elevation, warm) and Popayan (1850 m elevation, cool), Colombia, and mature seed size, cotyledon cell number and volume per cell were determined. SGR (dry matter basis) increased with both increasing cell number per seed and increasing cell volume. Growth rate per cell was linearly related to cell volume at both sites. The association of large cell size with Andean background was the dominant factor responsible for large seed size and rapid SGR of Andean genotypes. The smaller seed size and SGR of Andean lines at the warmer site appeared to be a result of smaller cell number without compensating increases in cell volume or cell growth rate.