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Soil physical and chemical properties play a central role in plant growth, influencing the availability of air, nutrients, and water. The aim of this two-year study was to evaluate the effect of soil texture and chemical properties (pH, electrical conductivity, organic carbon, organic matter, total, and active lime) on saffron (Crocus sativus L.) growth, yield, and quality. Corms were planted in pots filled with seven different soil textures obtained mixing an increasing quantity (33% and 66%) of sand to a clay soil (S1) and to a clay loam soil (S2) compared to a full (100%) sandy soil as a control (S7). A randomized complete block design comprising of seven pots with different types of soil (S1, S2, S3, S4, S5, S6, and S7) replicated three times was used. The results showed that the highest flower number (320.3 n m−2), stigma yield (2.0 g m−2), daughter corm production (7.9 kg m−2), and horizontal diameter (3.1 cm) were derived from S3 and S4 soils. These were characterized by a loam and sandy-loam texture, not very calcareous, with a sub-alkaline and neutral pH, low electrical conductivity, a content of organic matter between 5.46 and 8.67 g kg−1, and a content of active lime between 21.25 and 26.25 g kg−1. According to International Organization for Standardization (ISO) references, although all spice samples belonged to the first qualitative category, S1, S3, and S2 soils recorded the highest value for coloring power (290.5, 289.1, and 287.6 A1%1cm 440 nm, respectively). The highest values of bittering (109.2 A1%1cm 257 nm) and aromatic (26.6 A1%1cm 330 nm) power were reached by S3 soil. Positive correlations were found both between color with clay and organic matter, and aroma with total calcium carbonate. In conclusion, the assessment of soil conditions is particularly important to obtain the best saffron performance in terms of stigma and daughter corms yield as well as spice qualitative traits.

Saffron ( Crocus sativus L.) is among the world’s most expensive spices, prized for its red stigmas used as a flavoring and a natural dye. Saudi Arabia is a significant importer of saffron, but the high cost of importing quality corms makes it economically unfeasible relative to the potential income from saffron production. Additionally, the high temperatures and harsh conditions of open fields pose significant challenges for saffron cultivation in the region. We investigated saffron cultivation under controlled greenhouse conditions with cooling to address these issues. Our study examined three plant densities—200, 100, and 67 corms m - ²—and two planting depths—8 cm and 13 cm—to assess their effects on plant growth, flower yield, stigma production, and new corm development. We found that higher plant density (200 corms m - ²) increased flower, and stigma yields per unit area but decreased flower number, stigma production, and plant weight per individual plant. Deeper planting (13 cm) reduced new corm production, particularly at the highest density. The largest corms and the highest percentage of big corms were observed at the lowest density (67 corms m - ²), with planting depth having minimal impact on corm production. Given the high cost of quality corms, balancing flower production per corm with reproductive capacity is crucial. Therefore, based on our findings, we recommend a moderate planting density of 100 corms m - ² and a shallow planting depth of 8 cm. These conditions provide a more balanced approach, optimizing both flower yield and corm production. Implementing these recommendations could enhance the efficiency and sustainability of saffron cultivation in greenhouses with cooling, making it a viable option for regions with challenging growing conditions.

The effect of the corm size of saffron (Crocus sativus L.) and the planting density was determined on a field study for six years. The objective of the present study was to determine the impact of the corm size and planting density on flower and stigma yields. Two corm sizes were used: corms with a diameter up to 2.5 cm and corms with a diameter greater than 2.5 cm, and five planting density: 22, 27, 33, 44 and 67 corms/m2 with planting distances 30, 25, 20, 15 and 10 cm on the plant row, respectively. The results showed that the year (growing season) and the interaction of year (growing season) with corm size affected all the characteristics that were studied. Over the six-year study period, there was a gradual increase in flowering from the first to the third year, followed by a decline in the fifth and sixth years. The yield of larger corms (greater than 2.5 cm) was higher during the first three years, while smaller corms (less than 2.5 cm) produced higher yields in the fourth through sixth years. On the contrary, the planting density, did not significantly affect the characteristics studied over the six years of cultivation and therefore did not affect the stigma yield of saffron. Therefore, corm size together with the environment are important factors that can affect the productivity and the longevity of the crop and should be considered when planting a new saffron cultivation.

The effects of four plant growth regulators on Crocus sativus L. (saffron) yield and performance were studied in two consecutive years under field conditions. Saffron corms were immersed in solutions of gibberellic acid (GA3), salicylic acid (SA), paclobutrazol (PBZ), chlormequat chloride (CCC), distilled water (hydroprime), and dry corms as the control. Results showed that among the different treatments, plants primed with GA3 500 μM had the highest flower fresh weight and stigma dry weight. In contrast, primed corms with 1000 μM CCC and 100 μM PBZ had the lowest flower dry weight. Furthermore, the plants primed with SA 1400 had the highest leaf numbers, leaf dry weight, and leaf area index (LAI). Plants treated with GA3 induced narrow but the longest leaves, while those treated with SA showed the widest ones. It was also demonstrated that the application of CCC and PBZ can produce shorter leaves. Furthermore, the greatest numbers of daughter corms were obtained in 1400 μM SA. Both PBZ and CCC were reported to have no impacts on the corm numbers but produced larger and heavier daughter corms. The results revealed that the priming of saffron corms with GA3 and then SA improved saffron growth and yield.

The characterization of C. sativus ecotypes is of great interest for preserving them from a possible genetic erosion due to the decrease of European cultivation surface. In this study, we evaluated four ecotypes from Italy (Sardinia and Abruzzo), Spain (Castilla-La Mancha), and Greece (Kozani) in order to detect the existence of variability and promote the biodiversity of this crop. Thirty-one traits related to saffron flowering, flower morphology, production of spice and daughter corms, vegetative development (leaf and corm traits), and spice quality, were evaluated. In addition, a genetic analysis through three PCR-based approaches, SSRs, RAPD, and SRAP was assessed. Results highlighted a phenotypic variation among ecotypes during two consecutive years. All the studied parameters were influenced by the ecotype except for the stamen length, color coordinates of tepals, leaf length, and leaf number per plant. Sardinia had a longer flowering interval, earlier flowering, and higher spice yield and quality than the other corm origins. The maximum values of morphological traits, such as stigma length, dry weight of stigmas, tepals, flowers and leaves, leaf area, and daughter corm weight were observed in the Abruzzo ecotype. Principal component analysis (PCA) showed a clear separation among ecotypes, in which Sardinia and Spain showed more similarities than Abruzzo and Kozani. Significant negative correlation was found between days to flower with stigma yield and quality. However, we could not find molecular markers discriminating among corm origins. In conclusion, this study suggests the importance of C. sativus ecotypes as precious source of biodiversity and bioactive compounds, and of their enhancement as fundamental prerequisite for a sustainable development strategy and as an agricultural diversification opportunity for growers.

The stigma exsertion rate (SER) is a key trait for the outcrossing ability of hybrid rice, which directly affects the yield of hybrid seeds in hybrid seed production. In previous studies, we have located 18 QTLs for SER using single-segment substitution lines in rice. In this study, we found that 4 of 18 QTLs for SER controlled stigma size (SS). On chromosome 1, a QTL qSL-1 controlling stigma length (SL) was located at the same interval of qSER-1b . On chromosome 2, two QTLs for SS, qSS-2a and qSS-2b , linked closely within a 1288.0 kb region, were at the same positions of qSER-2a and qSER-2b , respectively. A QTL qSL-12 controlling SL on chromosome 12 was at the same location of qSER-12 . Additive effects of four QTLs for SS ranged from 0.12 mm to 0.38 mm, showing significant effects on SS. In pyramiding lines of QTLs for SS, SS enlarged with the increase of QTLs. The effect of QTLs on SER was consistent with their effect on SS, and SL had a greater positive effect on SER than the stigma width. Our findings demonstrate that SS is one of the important factors affecting SER in rice.

Seed yield is one of the main limitations in hybrid rice production. The improvement of stigma exsertion rate (SER) of male sterility lines is essential for the higher seed yield in hybrid rice. Wild rice species are valuable germplasms with exserted stigma. It is worthy of mining-related genes for SER in wild rice species, as well as probing the way to use the beneficial genes in rice breeding. In the present study, we identified a total number of 36 stable QTLs for the SER distributing on 11 chromosomes by using a set of single-segment substitution lines (SSSLs) of 3 AA-genome wild rice species, O. barthii , O. meridionalis , and O. rufipogon . The mean genetic effects of these QTLs were ranged from 14.50 to 41.25% during 2016–2017. Twelve QTLs among them were novel by comparing the chromosome intervals with the reported QTLs. Besides, 7 homozygous 2-QTL pyramiding lines (PLs) were developed in BAR-SSSLs and MER-SSSLs to detect QTL interactions on the same background of HJX74. The epistatic effects in 3 out of 7 QTL pairs were positive, including qSERb3-1/qSERb6-1 , qSERb3-1/qSERb8-1 , and qSERb3-1/qSERb12-1 , which mean epistatic effect was 13.56%, 4.76%, and 7.29% in 2018–2019, respectively. The PL of B6/B19 ( qSERb3-1 / qSERb12-1 ) had the highest mean SER of 80.59% and the largest pyramiding effect of 55.51%. The results in the present study demonstrated that SSSLs were the elite materials for SER QTL detection from wild rice species, and elite PLs could be developed among SSSLs for SER improvement in hybrid rice breeding.

High seed cost due to poor seed yield severely limits the adoption of hybrid rice by farmers. Increasing the out-crossing rate is one of the key strategies to increase hybrid seed production. Out-crossing rate is highly influenced by the size of female floral traits, which capture pollen grains from male donor plants. In the current study, we identified 14 QTLs derived from the perennial wild rice Oryza longistaminata by composite interval mapping for five key floral traits: stigma length (five), style length (three), stigma breadth (two), stigma area (one), and pistil length (three). QTL analysis and correlation studies revealed that these stigma traits were positively correlated and pleiotropic to the stigma length trait. We selected the major-effect QTL qSTGL8.0 conferring long stigma phenotype for further fine mapping and marker-assisted selection. The qSTGL8.0 (~ 3.9 Mb) was fine mapped using newly developed internal markers and was narrowed down to ~ 2.9 Mb size (RM7356–RM256 markers). Further, the flanking markers were validated in a segregating population and in progenies from different genetic backgrounds. The markers PA08-03 and PA08-18 showed the highest co-segregation with the stigma traits. The qSTGL8.0 was introgressed into two cytoplasmic male sterile (CMS) lines, IR58025A and IR68897A, by foreground, background, and trait selection approaches. The qSTGL8.0 introgression lines in CMS backgrounds showed a significantly higher seed setting rate (2.5–3.0-fold) than the original CMS lines in test crosses with their corresponding maintainer lines. The newly identified QTLs especially qSTGL8.0, will be quite useful for increasing out-crossing rate and this will contribute to increase seed production and decrease seed cost.

Wheat yield mainly depends on thousand-grain weight, spike number per unit, and grain number per spike. Since fertility is directly related to seed setting rate and grain number, the discovery of novel genes and alleles affecting male or female sterility is essential for advancing the genetic understanding of wheat fertility. Here we identified a wheat mutant on anther–stigma development ( asd) , exhibiting both male and female sterility with thin shriveled non-dehiscent anthers that failed to release pollen, as well as visorless stigmas. Cytological examination of asd showed a lack of cutin polymer on anther surfaces and extensive microspore mother cell degeneration leading to pollen deficiency. Using MutMap + and exome capture sequencing, we mapped one target gene on chromosome 2D, narrowing it a 1.62-Mb interval, and identifying TraesCS2D03G0987000 ( TaTPR1 ), which encodes a conserved TOPLESS-related protein, as the candidate gene. TaTPR1 harbored a single base mutation (G > A) at the junction of the 6th intron and 7th exon, which disrupted splicing resulting in three transcripts. TaTPR1 expression levels were elevated in mutant anthers and ovaries, with subcellular localization confirming its presence in the nucleus and cytoplasm. Various allelic mutations within TaTPR1 exerted distinct impacts on pollen fertility and stigma development and led to reduced self-setting rates, which verified TaTPR1 to be the target gene. This study identified a crucial novel gene affecting both male and female sterility in wheat, which offers new insights into fertility mechanisms.

Under natural conditions, most Hibiscus syriacus L. individuals form very few mature seeds or the mature seeds that do form are of poor quality. As a result, seed yield is poor and seeds have low natural germinability. These phenomena strongly hinder utilization of the excellent germplasm resources of H. syriacus . The study has shown that pollen activity and stigma receptivity were high on the day of anthesis, and the pistils and stamens were fertile. Pollen release and stigma receptivity were synchronous. But in styles following self and cross-pollination, pollen tube abnormalities (distortion and twisting of the pollen tubes) and callose deposition were observed. Cross-pollinated pollen tubes elongated faster and fewer pollen tube abnormalities were observed compared with self-pollinated pollen tubes. And during embryo development, abnormalities during the heart-shaped embryo stage led to embryo abortion. Imbalance in antioxidant enzyme activities and low contents of auxin and cytokinin during early stages of embryo development may affect embryo development. Therefore, a low frequency of outcrossing and mid-development embryo abortion may be important developmental causes of H. syriacus seed abortion. Nutrient deficiencies, imbalance in antioxidant enzyme activities, and a high content of abscisic acid at advanced stages of seed development may be physiological causes of seed abortion.