Changes of Stem Characteristics, Senescence Indexes and Yield and Quality of Wintering Rye under Different Populations

In response to the production crisis caused by a winter feed shortage due to the rapid development of the animal husbandry industry, winter rye 001 was selected to study differences in stalk and senescence characteristics in yield formation in cold regions. Five density treatments were established in a randomized design as 225 × 104 plant·hm−2 (D1), 275 × 104 plant·hm−2 (D2), 325 × 104 plant·hm−2 (D3), 375 × 104 plant·hm−2 (D4), and 425 × 104 plant·hm−2 (D5). Stem characteristics, SOD activity, POD activity, MDA content, and differences in yield and feeding quality under different population densities were analyzed. The plant height, center of gravity, and stem basal internode length showed an increasing trend with an increase in planting density. The stem wall thickness, diameter, strength, and lodging resistance indices decreased. At 275 × 104 plants·hm−2, the rye crude protein content was the highest while neutral washing fiber and acid washing fiber were the lowest, and feed quality was the best. With an increase in density, spike number, grain number per spike, and thousand-grain weight first increased and then decreased. We concluded that the yield and feeding quality were best when the basic seedling was at 275 × 104 plants hm−2.

Morphological, Anatomical, and Chemical Characteristics Associated With Lodging Resistance in Avena Sativa

In subtropical environments, lodging occurs at all stages of an oat plant development, particularly after panicle's appearance, causing severe yield reduction. This study's objective was to identify the morphological, chemical, and anatomical characteristics of the culm that are associated with lodging resistance in oats and that can be used to identify and select resistant genotype. A set of different genotypes with diverse response to lodging were grown in nine environments, combining sowing densities, years, and growing seasons within the same year. Were carried out morphological, anatomical, and chemical evaluations for primary culms. Shorter culm length and larger culm thickness in the first expanded basal internode are morphological characteristics associated with lodging resistance in Avena sativa. No differences in lignin and cellulose contents were observed, however, there were differences in the distribution pattern and in the intensity of staining of lignin and cellulose. Resistant genotypes showed higher number of layers of cells in the subdermal parenchyma. The most practical and easily selectable feature for lodging resistance in a breeding program remains plant height together with culm thickness in the first basal internode.

Basal Rachis Internode Injection (BRII): A novel inoculation method to evaluate wheat resistance to Fusarium head blight

Fusarium head blight (FHB) is one of the most destructive fungal diseases of wheat. Difficulties in reliably phenotyping of this disease, however, greatly hindered the understanding of the mechanism of wheat-pathogen interaction and genetic improvement of FHB resistance. Here we report a novel inoculation method called “Basal Rachis Internode Injection” (BRII), which is implemented by injecting inoculum into the basal internode of a rachis instead of a floret as done in single floret inoculation (SFI). One of the prominent advantages of BRII over SFI and other traditional methods lies in its independence of moisture-maintaining system that is required for all existing methods, thus being insensitive to environmental humidity and cost-effective. Another unique feature for BRII is that this method produces nearly clear-cut reaction types, by which FHB resistance could be treated as a qualitative trait because generally no FHB symptom appeared on the spikelets of resistant genotypes. In addition, BRII outperformed SFI by higher infection rate and better goodness-of-fit with known FHB resistance and QTL components in a panel of 15 genotypes, as well as two populations of recombinant inbred lines (RILs) segregating in Fhb1. To be noteworthy, BRII and SFI methods are not mutually replaceable but rather complimentary to each other since each method has its own advantage in differentiating FHB resistance among genotypes. Combining these two methods would significantly improve the reliability and consistency of FHB phenotyping in wheat.

Genetic evaluation of tidal swamp rice from South Kalimantan, Indonesia based on the agro-morphological markers

Mursyidin DH, Khairullah I. 2020. Genetic evaluation of tidal swamp rice from South Kalimantan, Indonesia based on the agro-morphological markers. Biodiversitas 21: 4795-4803. A total of 71 cultivars of the tidal swamp rice (Oryza sativa L.), originated mainly from South Kalimantan, Indonesia, were evaluated agro-morphologically by using 26 qualitative and 13 quantitative traits. Based on these traits, this germplasm is generally low in diversity. However, three agro-morphological traits, namely the tillering abilities, seedling height, and diameter of the basal internode, shows the relatively highest diversity, shown by the Lakatan Putih, Pandak Putih, and Bayar Papuyu, respectively. The UPGMA and PCA revealed that this germplasm divided into six main clusters, where the sixth cluster is the largest with a total membership of 60 cultivars. The cluster analysis also revealed that Lakatan Siam is far separate from other cultivars. Thus, this finding might be useful in the future rice breeding programs, particularly in developing new rice cultivar for the tidal swamp areas.

Nitrogen Split Application Can Improve the Stalk Lodging Resistance of Maize Planted at High Density

The decrease of maize stalk quality is an important reason for stalk lodging during the grain filling stage. In the present study, a maize cultivar was planted at densities of 7.5, 9.0, 10.5, 12.0, and 13.5 × 104 plants ha−1 and subjected to nitrogen application rates of 0, 270, 360, and 450 kg ha−1 (denoted as N0, N270, N360, and N450). The stalk breaking force, mechanical strength, carbohydrate content, and nitrogen content of basal internodes were determined to study the effects of nitrogen application rate on the stalk lodging resistance of maize under different planting densities with integrated watering and fertilization using drip irrigation. At densities of 7.5 to 10.5 × 104 plants ha−1, the stalk breaking force, rind penetration strength (RPS), and crushing strength (CS) of the basal internode decreased first and then increased with increasing nitrogen application rate, with the lowest values obtained for the N270 treatment. Meanwhile, at planting densities of 12.0 × 104 plants ha−1 and above, the stalk breaking force, RPS, and CS increased with increasing nitrogen application rate. The basal internode dry weight per unit length (DWUL) and total N content increased with increasing nitrogen application rate. The breaking force was significantly positively correlated with the DWUL and mechanical strength of the basal internode. The RPS showed a positive linear correlation with the contents of cellulose, lignin, and total N of the third internode. Under the split application of water and fertilizer, the maize stalk total dry matter and contents of cellulose, lignin, and total nitrogen increased with increasing nitrogen fertilization rate during the grain filling stage at high planting density, so the stalk lodging resistance improved.

Effects of uniconazole or ethephon foliar application on culm mechanical strength and lignin metabolism, and their relationship with lodging resistance in winter wheat

Lodging in plants is an important constraint that leads to yield losses and cause problems with mechanical harvesting. This research was aimed at determining the effects of foliar application of uniconazole or ethephon on lignin metabolism, characteristics of second basal internode and their relationship with lodging resistance in winter wheat (Triticum aestivum L.). In separate experiments, uniconazole was sprayed on the foliage at concentrations of 0, 15, 30 and 45 mg L–1, and ethephon at concentrations of 0, 50, 75 and 100 mg L–1 at the four-leaf stage. Foliar application of uniconazole or ethephon significantly reduced the lodging rate by increasing the lignin content and optimising basal-internode characteristics. Lignin content was significantly positively correlated with breaking strength, and negatively correlated with lodging rate, whereby the higher lignin content in the second basal internode significantly improved the lodging resistance and reduced the lodging rate in the wheat crop. Foliar application of uniconazole or ethephon also increased the breaking strength, internode diameter, wall thickness and internode plumpness of the second basal internode; maximum values were obtained with uniconazole at 30 mg L–1 and with ethephon at 75 mg L–1. Grain yield, lignin content and lignin-related enzyme activities of phenylalanine ammonia-lyase, tyrosine ammonia-lyase, cinnamyl alcohol dehydrogenase and peroxidase were all significantly improved with the foliar application of uniconazole or ethephon. These results suggest that lignin content in the second basal internode in wheat was closely related with lodging resistance. Foliar application of uniconazole or ethephon at the four-leaf stage reduced the lodging rate, and the concentration showing the greatest effects was 30 mg L–1 for uniconazole or 75 mg L–1 for ethephon.

Stem lodging parameters of the basal three internodes associated with plant population densities and developmental stages in foxtail millet (Setaria italica) cultivars differing in resistance to lodging

Foxtail millet (Setaria italica (L.) Beauv.) is a soft-stemmed summer cereal crop that is grown at a high crop density; however, stem lodging is recognised as a serious yield-limiting factor. The stem-breaking strength of the third to fifth basal internodes has previously been identified as the most important factor in determining the lodging resistance of foxtail millet. We measured variation in stem-breaking strength, length and weight of these internodes at different developmental stages and in response to different crop densities by using foxtail millet cultivars that differed in lodging resistance. The stem-breaking strength of the third internode was greater than of the fourth and fifth internodes, which had comparable stem-breaking strengths; this result was independent of genotype and developmental stage. The stem-breaking strengths of the three internodes were significantly correlated with each other and linearly related across different developmental stages and crop densities. The stem-breaking strength of the three internodes at hard dough stage (Zadoks growth stage Z87, at 30 days after flowering) was less than at other developmental stages in the lodging-resistant genotypes. Stem-breaking strength for the three internodes was correlated with fresh weight (FW) and dry weight (DW) per cm. The variation of FW and DW per cm of the internodes in response to crop density was attributed to the change of FW and DW of the corresponding internodes, rather than to variation in their length. Results from this study showed that the fourth or fifth basal internode was more prone to lodging than the third basal internode because of their lesser stem-breaking strength. Crop density linearly influenced the stem-breaking strength of the three basal internodes. Reducing crop density enhanced stem-breaking strength of third to fifth internodes, which may reduce the risk of stem lodging in this crop. Based on the findings, the stem-breaking strength of the fourth or fifth basal internode measured at the late grain-filling stage from Z77 (late milk) to Z87 (hard dough) differentiated stem-breaking strength, the most important stem lodging associated parameter, in the foxtail millet genotypes.

Ethephon improved stalk strength associated with summer maize adaptations to environments differing in nitrogen availability in the North China Plain

SUMMARYNitrogen (N) supply is essential for achieving high grain yield in maize production, but excessive N application can lead to lodging risks and potential yield loss. The main objective of the present study was to investigate the effect of ethephon application under different N fertilizer rates in reducing maize lodging. Field experiments were conducted to determine the interactive effects of ethephon (0 and 180 g/ha) and N rate (0, 75, 150 and 225 kg N/ha) on the morphological and chemical characteristics of basal internode and yield across two summer maize-growing seasons (2011/12) in Wuqiao of the North China Plain. Findings showed that ethephon significantly increased the maximum diameter of the 7th to 14th internodes, and decreased the internode lengths, which led to a decrease in plant and ear heights under different N rates. Significant ethephon × N interaction effects were observed on the diameter and length of internode, dry weight per unit internode length and breaking resistance. Ethephon significantly increased N, cellulose and hemicellulose contents of the basal internode, but cellulose and hemicellulose contents decreased as the rate of N application increased. Internode diameter, dry weight per unit internode length, and N content of the basal internode were significantly positively correlated with breaking resistance. Ethephon significantly increased grain yield and harvest index in 2011, but not in 2012. Grain yield and above-ground biomass were increased with increasing N application in both growing seasons, showing linear and quadratic responses. These results suggested that ethephon could increase stalk strength by improving the morphological and chemical characteristics of the basal internode, and maintain high yield and biomass under high N rates.