Evaluation of gamma-irradiated Pisum sativum germplasm for agronomic traits and tolerance to Didymella pinodes

The development of cassava (Manihot esculenta Crantz) with a high yield under water-deficit conditions is one of the goal of the breeding programs. The objective of this study was to evaluate the performance and to select cassava accessions based on drought tolerance indices and productive potential under water stress. Forty-nine accessions were evaluated for five agronomic traits (plant height—PH, root yield—RoY, shoot yield—ShY, harvest index—HI; and dry matter content of roots—DMC) under full irrigation conditions and drought stress (DS). The accessions were selected based on: (i) high yield under drought conditions (HY-DS) and (ii) high drought tolerance (Dr-To) based on six different indices. Overall, water stress dramatically reduced the traits’ means (RoY—72.98%, ShY—54.95%, DMC—26.15%, HI—31.05%, and PH—32.95%). Low coincidence among the top ten accessions was identified based on HY-DS and Dr-To criteria. Therefore, considering only the most important traits (RoY and ShY), five accessions (BGM0815, BGM0598, 9624-09, BGM0818, and BRS Formosa) presented high HY-DS. In contrast, to Dr-To criterion, eight and nine accessions were selected for high yield of the aerial part (ShY and PH) and roots (RoY and DMC), respectively. The mean productivity, geometric mean productivity, and drought tolerance indices were the most promising to identify genotypes with high agronomic attributes, while drought susceptibility index, susceptibility, and yield stability index were suitable to identify the most drought tolerant accessions. This set of selected accessions can be used in breeding programs aimed at high yield and drought tolerance.

Low-phosphorus (LP) stress is a global problem for maize production and has been exacerbated by breeding activities that have reduced the genetic diversity of maize. Although LP tolerance in maize has been previously evaluated, the evaluations were generally performed with only a small number of accessions or with samples collected from a limited area. In this research, 826 maize accessions (including 580 tropical/subtropical accessions and 246 temperate accessions) were evaluated for LP tolerance under field conditions in 2011 and 2012. Plant height (PH) and leaf number were measured at three growth stages. The normalized difference vegetation index (NDVI) and fresh ear weight (FEW) were also measured. Genetic correlation analysis revealed that FEW and NDVI were strongly correlated with PH, especially at later stages. LP-tolerant and -sensitive accessions were selected based on the relative trait values of all traits using principal component analysis, and all the 14 traits of the tolerant maize accessions showed less reduction than the sensitive accessions under LP conditions. LP tolerance was strongly correlated with agronomic performance under LP stress conditions, and both criteria could be used for genetic analysis and breeding of LP tolerance. Temperate accessions showed slightly better LP tolerance than tropical/subtropical ones, although more tolerant accessions were identified from tropical/subtropical accessions, which could be contributed by their larger sample size. This large-scale evaluation provides useful information, LP-tolerant germplasm resources and evaluation protocol for genetic analysis and developing maize varieties for LP tolerance.

Grass pea (Lathyrus sativus) represents a promising legume crop for resource-limited farmers due to its resilience against various environmental stresses. It is valued for its high protein content and unique nutritional profile, including being the sole known dietary source of L-homoarginine. However, its cultivation remains constrained compared to other pulse crops due to the neurotoxic amino acid β-N-oxalyl-L-α, β-diaminopropionic acid (β-ODAP), which can induce neurolathyrism upon excessive consumption of seeds and green tissues. The objective was to screen these accessions for traits crucial to breeding programs like low ODAP content, high yield potential, and drought tolerance. The present investigation on grasspea carried out at Instructional cum Research Farm, Department of Genetics and Plant Breeding, College of Agriculture, Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G) during rabi season to screen 89 germplasm/accessions along with check Prateek for low ODAP, high yield and drought tolerance. Screening of genotypes revealed that sufficient amount of variability was present for ODAP content, yield and drought tolerance. 20 most drought tolerant, low ODAP and high yielding genotypes were selected which should be used in future breeding programme.

Pre-harvest sprouting (PHS) of wheat reduces the quality of wheat grain, and improving PHS tolerance is a priority in certain wheat growing regions where conditions favorable for PHS exist. Two new Viviparous-1 allelic variants related to PHS tolerance were investigated on B genome of bread wheat, and designated as Vp-1Bb and Vp-1Bc, respectively. Sequence analysis showed that Vp-1Bb and Vp-1Bc had an insertion of 193-bp and a deletion of 83-bp fragment, respectively, located in the third intron region of the Vp-1B gene. The insertion and deletion affected the expression level of the Vp1 at mature seed stage, more correctly spliced transcripts were observed from the genotypes with either insertion or deletion than that of the wild type. Based on these insertions and deletions, a co-dominant STS marker of Vp-1B gene was developed and designated as Vp1B3, which in most cases could amplify either 845 or 569-bp fragment from the tolerant cultivars, and 652-bp from the susceptible ones. This Vp1B3 marker was mapped to chromosome 3BL using a set of Chinese Spring nulli-tetrasomic and ditelosomic lines. A total of 89 white-grained Chinese wheat cultivars and advanced lines, were used to validate the relationship between the polymorphic fragments of Vp1B3 and PHS tolerance. Statistical analysis indicated that Vp1B3 was strongly associated with PHS tolerance in this set of Chinese germplasm, suggesting that Vp1B3 could be used as an efficient and reliable co-dominant marker in the evaluation of wheat germplasm for PHS tolerance and marker-assisted breeding for PHS tolerant cultivars.

IntroductionAlkaline stress poses a major challenge to crop productivity, often causing more severe physiological damage than saline stress alone. Maize is particularly sensitive to alkaline conditions, which significantly inhibit germination and early growth. The establishment of accurate evaluation systems for alkali tolerance is therefore crucial for the development of resilient cultivars.MethodsA total of 42 maize germplasm accessions were evaluated under simulated alkaline stress (100 mM) during germination. A comprehensive analytical framework integrating principal component analysis, membership function analysis, stepwise regression, cluster analysis, and discriminant analysis was used to assess alkalinity tolerance. The Lindeman–Merenda–Gold method was further employed to quantify the relative contribution of each morphological trait to the comprehensive alkali tolerance score.ResultsAlkaline stress significantly inhibited early seedling growth, and several germination-related traits showed strong associations with alkali tolerance. Based on the comprehensive D value, the maize accessions were classified into five tolerance groups. Trait contribution analyses consistently indicated the germination index (GI) and the shoot dry weight (SDW) as the strongest determinants of tolerance, with root length (RL) and root fresh weight (RFW) also playing notable roles. These indicators form a reliable basis for the screening of alkali-tolerant maize germplasm, providing a foundation for future refinement of the evaluation system through physiological or molecular approaches.DiscussionThis integrated evaluation system effectively distinguishes maize germplasm by alkali tolerance level and identifies key morphological determinants. The findings provide a scientific basis for germplasm screening and breeding of alkali-tolerant maize materials, contributing to sustainable agricultural production in saline–alkaline environments.

Pre-harvest sprouting (PHS) of wheat greatly reduces the quality and economic value of grain, and PHS tolerance is one of the most important traits in wheat breeding. Two new Vp-1B alleles were identified in wheat genotypes with distinct PHS tolerance and ABA responsiveness and designated as Vp-1Bb and Vp-1Bc. These alleles had an insertion of 193-bp and a deletion of 83-bp in the third intron in the region of B3 domain, respectively. Further analysis indicated that different Vp-1B alleles showed different expression and responsiveness to ABA exposure at transcriptional level, implying that they may regulate PHS tolerance. Based on these alleles, a STS marker Vp1B3 was developed and validated among a set of 89 Chinese wheat accessions. The results indicated that Vp1B3 may be useful as an efficient and reliable co-dominant marker in the evaluation of wheat germplasm for PHS tolerance and marker-assisted breeding for PHS tolerant cultivars. Moreover, analysis of a collection of 490 EU winter wheat varieties revealed not only the prevalence of Vp-1B alleles but also a new allele Vp-1Bd which does not occur in Chinese wheats.

Through potted plant experiments,drought tolerance of 14 cassava cultivars at seedling stage under water stress was measured.Comprehensive principal components analysis,cluster analysis and correlation analysis showed that the drought tolerance coefficient(DTC) of peroxidase(POD) activity,soluble protein content(Pr) content,malondialdehyde(MDA) content,free proline(Pro) content,plant height and stem diameter were 0.14–4.00,0.12–3.28,0.55–1.76,0.33–1.70,0.68–1.09 and 0.62–1.05,respectively.POD activity showed the largest correlation coefficient with F value(the comprehensive analysis),followed by Pr content,plant height,stem diameter,Pro content and MDA content.POD activity and Pr content were very significantly positive correlated to F value,and there was very significantly positive correlation between POD activity and Pr content.After comprehensive comparison,POD activity and Pr content were recommended as the main indexes for evaluation of drought tolerance of cassava seedlings.

Evaluation of rice germplasm for drought tolerance under rainfed lowland condition in Cambodia

Hevea brasiliensis is a commercially cultivated species for its natural rubber (NR) latex in South East Asian countries. To meet the ever-increasing demand, NR cultivation has been extended to non-traditional regions due to the limited scope of further expansion in traditional rubber-growing areas in India. These areas are often confronted with various abiotic stresses, especially high and low temperatures, which cause reduction in plant growth, thereby increasing its uneconomical immaturity period. Eighteen wild Hevea accessions along with two modern clones RRII 203 and PB 235 and two check clones RRIM 600 and Haiken 1 were evaluated in the early mature growth phase. The site was at Nagrakata, West Bengal, the sub-Himalayan cold-prone region of India. In Hevea, crop production is governed by two major factors, growth-vigor and production capacity. Growth-vigor is of special importance because the production of rubber is a process linked with the early growth of the plant, which results in early tappability and early economic gains. The genotypes exhibited highly significant clonal differences (P = 0.05) for all the growth traits. Tappability percentage in the seventh year, ranged from 0.33 % (AC 3074, AC 3075, AC 3293) to 89.67 % (RO 2727). The most vigorously growing accession (RO 2727) reached tappabile girth early in the seventh year when the girth of plant ranged from 22.38 cm (AC 3293) to 53.12 cm (RO 2727). The general mean was 43.32 cm, and the similar growth trend was exhibited by these accessions in the tenth year also. Annual girth increment (cm a−1) over 3 years ranged from 1.81 cm (AC 3075) to 6.80 cm (RO 2727). The mean winter girth increment (cm a−1) over 4 years ranged from 0.13 cm (AC 3075) to 0.96 cm (RO 2727) as compared to the check clone RRIM 600 (1.11 cm) and Haiken 1 (1.10 cm). Wide differences between the phenotypic coefficient of variation (50.29) and genotypic coefficient of variation (24.82) were observed for winter girth increment. Girth in the tenth year recorded the highest heritability (87 %). Girth was significantly correlated with the other growth traits. The top 30 % of the potential accessions showing high growth vigour and early tappability under cold stress were identified. These ecotypes/selections have high potential value for the development of cold-tolerant clones for these regions and also in broadening the genetic base of the present-day cultivated rubber.

Soil salinity represents a major constraint limiting crop production in arid and semi-arid countries. The effect of salinity induced by sodium chloride (NaCl) at five levels (0, 50, 100, 150 and 200 mM) was investigated on four germination traits and thirteen seedling growth characteristics in twenty cowpea [Vigna unguiculata (L.) Walp.] genotypes (ET11, KEB-CP004, KEB-CP006, KEB-CP009, KEB-CP 010, KEB-CP020, KEB-CP033, KEB-CP038, KEB-CP039, KEB-CP045, KEB-CP051, KEB-CP054, KEB-CP057, KEB-CP060, KEB-CP067, KEB-CP068, KEB-CP118, MTA22, NO74 and NO1036). The germination tests were carried out on Petri dishes in the laboratory while seedling growth experiments continued in plastic pots in the greenhouse, both setting up using a randomised complete block design with three replications. Genotypic responses were significant for all germination traits (p < 0.001). Germination percentage, germination rate index, and coefficient of velocity of germination were all decreased by salt stress. However, the mean germination time increased with increasing saline conditions. Significant differences were found between genotypes for most growth attributes. Growth rate (centimeter increased in height per week) decreased significantly with increasing salinity, starting at 100 mM NaCl (24.20% reduction, 2.66 cm / week) with maximum reduction (38.58%) corresponding to 2.16 cm/week observed at 200 mM NaCl, compared to control (3.51 cm/week growth rate). Also, significant decline in shoot weights, number of functional leaves and dry matter production were observed under salinity. Salinity also reduced water content in shoot and root and did not affect root weights. Under salinity, significant correlations were found between all germination variables (p < 0.001). Growth rate was significantly associated with ten out of the twelve other seedling growth traits. Also, the dry matter production under salinity was significantly associated with all other seedling growth characteristics with the exception of root water content. Given the effect of salt stress, cowpea genotypes, namely NO1036, KEB-CP004, KEB-CP038 and KEB-CP051, were the most tolerant while KEB-CP068 and ET11 were the most sensitive ones. The results confirm substantial genetic variation in salt stress tolerance among the studied genotypes. The most tolerant genotypes should be further explored in genetic improvement programs and should be promoted for culture in regions affected by salinity.

For Ethiopia’s wheat production, drought is a major natural disaster. Exploration of drought-resistant varieties from a bulk of wheat germplasm conserved in the gene bank is of paramount importance for breeding climate change-resilient modern cultivars. The present study was aimed at identifying the best performing drought-resistant genotypes under non-stress and polyethylene glycol simulated (PEG) stress conditions in a growth chamber. Forty diverse Ethiopian bread and durum wheat cultivars along with three Chinese bread wheat cultivars possessing strong drought resistance and susceptibility were evaluated. After acclimation with the natural environment, the seedlings were imposed to severe drought stress (20% PEG6000), and 15 seedling traits including photosynthetic and free proline were investigated. Our findings indicated that drought stress caused a profound decline in plant water consumption (83.0%), shoot fresh weight (64.9%), stomatal conductance (61.6%), root dry weight (55.2%), and other investigated traits except root to shoot length ratio and proline content which showed a significant increase under drought stress. A significant and positive correlation was found between photosynthetic pigments in both growth conditions. Proline exhibited a negative correlation with most of the investigated traits except root to shoot length ratio and all photosynthetic pigments which showed a positive and non-significant association. Our result also showed a wide range of genetic variation (CV) ranging from 3.23% to 47.3%; the highest in shoot dry weight (SDW) (47.3%) followed by proline content (44.63%) and root dry weight (36.03%). Based on multivariate principal component biplot analysis and average sum of ranks (ASR), G12, G16 and G25 were identified as the best drought tolerant and G6, G42, G4, G11, and G9 as bottom five sensitive. The potential of these genotypes offers further investigation at a molecular and cellular level to identify the novel gene associated with the stress response.

Common bermudagrass (Cynodon dactylon L. Pers.) is a widely grown warm‐season turfgrass species characterized by a dense, deep‐rooted canopy and high levels of traffic tolerance. However, most cultivars have poor shade tolerance, which limits the use of these grasses in partly‐shaded areas. The identification of new sources of genetic resistance to shade will expand the germplasm pool available to breeders for developing improved bermudagrass cultivars. In this study, 24 common bermudagrass accessions recently introduced from South Africa were evaluated for their ability to persist under shade. Entries were established in a randomized complete block design with three replications at the Lake Wheeler Turfgrass Field Lab (Raleigh, NC) in the spring of 2019. Following full green‐up in summer 2020, entries were evaluated for performance under full sun, and then a 63% shade cloth was installed over the plots. Traits evaluated under shade included: turfgrass quality, turfgrass density, genetic color, ground coverage, turfgrass regrowth and the normalized difference vegetation index (NDVI). A turfgrass performance index (TPI) was calculated to identify the top performers across all traits. Under full sun, seven accessions had comparable performance with ‘Celebration’ and ‘TifTuf’ across traits. Under shade, ‘Stil03’, ‘Q 47620’, ‘TifGrand’, ‘WIN10F’, Celebration, and TifTuf exhibited the highest TPI. Accessions with superior shade tolerance identified in this study represent novel germplasm that can be used in future breeding efforts to improve shade tolerance in bermudagrass.

Agronomic evaluation of F1 hybrid soybean [Glycine max (L) Merr.] will be useful for germplasm evaluation, recurrent selection, and estimating heterosis. We anticipated that vegetative heterosis, commonly observed in soybean, could increase early lodging and pod abortion, reducing grain yield. Under these circumstances, observed hybrid grain yield would not reflect the true potential of the hybrid as expressed in later generations. The Dt2 (semideterminate stem type) and S (short internode stem type) alleles have been shown to reduce excessive vegetative growth and lodging in narrow‐row production of inbred soybean. Our objectives were (i) to determine the per se effects and effects on heterosis, for agronomic traits, of the semideterminate (Dt2_) and short (S_) stem types in hybrid soybean, (ii) to assess their potential in facilitating germplasm evaluation and recurrent selection, and (iii) to determine if either stem type would be agronomically desirable in commercial hybrid soybean production. Near‐isogenic inbred lines and hybrid (F1) lines were evaluated replicated three‐row plots. The Dt2 and S alleles affected agronomic traits of hybrids and inbreds similarly. The Dt2 and S alleles hastened maturity, decreased plant height and lodging, and increased harvest index per se values. The Dt2 allele decreased seed weight and protein content. Both the per se and heterosis data suggest that the Dt2 and S alleles would not be consistently beneficial to germplasm evaluation or recurrent selection. The per se data suggest that the S allele might be useful for both inbred and commercial hybrid soybean.

Vegetable pea (Pisum sativum L. var. hortense) belongs to family Leguminoceae sub family Fabaceae. Pea is an important legume vegetable, extensively cultivated in the temperate regions and restricted to cooler altitudes in the tropics and winter season in the sub-tropics. It is a self-pollinated crop having diploid chromosome number, 2n=14. It is highly nutritious and capable of fixing atmospheric nitrogen. Being most important to growers and consumer, there is an urgent need to increase its productivity to fulfill the increasing demands throughout the year. The information usually needed for developing high yield varieties in a particular species pertains to the extent of genetic variability for desirable traits in the available germplasm. Evaluation of germplasm is the basic tool for identification of improved genotypes

Pea is an important grain legume and vegetable in the South of Europe where it is grown on small farms and gardens using traditional varieties and methods during the winter. Variability in old, unimproved varieties needs to be determined in order to create useful genetic variation for broadening the narrow genetic base of commercial cultivars and for making efficient use of available resources. One hundred and four unimproved pea varieties and ten elite cultivars were evaluated in 1991 and 1992 at two locations for seed and vegetable quality, canopy and agronomic traits. Significant genotype by environment (G × E) interactions were found for protein concentration, fresh seed size and weight, canopy traits, pod length and weight, days to flowering, and days to fresh seed and pod maturity. There were significant differences between unimproved pea varieties for all traits studied except for seed soluble sugars and seed tenderness. Most of the significant differences for seed and vegetable quality traits were observed in the unimproved germplasm from the South of Europe when compared with differences within the elite germplasm. Data from the evaluation of available pea germplasm provide information needed by breeders to develop varieties efficiently for the different needs of growers, processors and feed manufacturers. The relevance of these results in devising breeding strategies is discussed. Key words: Pisum sativum, seed and vegetable quality, field performance, genotype by environment interaction