Agronomic responses of selected improved sorghum [Sorghum bicolor (L.) Moench] varieties to scheduled water stress

Received: 2016-04-05 | Accepted: 2016-05-29 | Available online: 2017-09-30 http://dx.doi.org/10.15414/afz.2017.20.03.45-48 This study was designed to examine the effect of water regime on seed quality of five sorghum genotypes. Two laboratory experiments were conducted in two successive seasons (2014 2015-2015 2016) at the Regional Seed Center Laboratory, Agriculture Research Station (ARC), Elobied. The laboratory treatments were conducted as factorial experiments in a Randomized Complete Block Design (DCBD) with four replications. The estimated quality included seed germination test. The results showed that water regimes had significant effects on germination (%). The highest seedling length was recorded by well-watered plant. The highest seedling growth rate was recorded by plants under well-watered regime. Also the results revealed that genotypes were differing in germination percent, seedling length and seedling growth rate. The results indicated that Taggat genotypes scored the highest values of most seeds quality trials were measured in this study and it might be suitable for high quality and production under rain-fed condition. Keywords: germination, seed vigor, sorghum, Sorghum bicolor (L.) Moench, water regime References ABDALLA, H.M. and GAMAR, Y.A. (2011) Climate change: Selection of sorghum genotype with wide adaptation, AG-17, for rain-fed areas of Sudan. In International Journal of Agri. Science , vol. 1, no. 3, pp. 144–555. ACHAKZAI, A.K.K. (2009) Effect of water stress on imbibitions, germination and seedling growth of maize cultivars. In Sarhad J. Agric. , vol. 25, no. 2, pp. 165-172. ACHAKZAI, A.K.K. and BAZAI, Z.A. (2007) Effect of water stress on seedling growth of maize cultivars: In mannitol plus culture solution. In Int. J. Biol. & Biotech . vol. 4, n. 1, pp. 37–42. AGHAALIKHANI, M., ETEMADI, F. and AJIRLO, A.F. (2012) Physiology basis of yield difference in grain sorghum ( Sorghum bicolor L. Moench) in a semi-arid environment. In Journal of Agricultural and Biological Science , vol. 7, no. 7, pp. 18-24. AHMED, E.E. and ALAMAM, S.H. (2010) Sorghum ( Sorghum bicolor (L.) Moench.). Seed Quality as Affected by Type and Duration of Storage. In Sudan. Agric. Biol. J. N. Am ., vol. 1, no. 1, pp. 1–8. DELOUCHE, J.C. (1969) Planting seed quality. Beitwide cotton production . New Orleans: USDA. FOUGEREUX, J. et al. (1997). Water stress during reproductive stages affects seed quality and yield of pea ( Pisum sativum ). In J. Crop Sci , vol. 37, pp.1247–1252. HAMID, B.H. (2001) Overview of sorghum and millet in Sudan. Khartoum: Ministry of Science and Technology, ARC, Sudan. HARRINGTON, J.F. (1971) The necessity for high quality vegetables. In J. Hortscience , vol. 6, pp. 550–551. KENGA, R. et al. (2006) Genetic and phenotypic association between yield components in hybrid sorghum (S orghum bicolor (L.) Moench) populations . Zaria: Institute of Agricultural Research for Development (IRAD), Ahamadu Bello University, Department of Plant Science/IAR. MOOSAVI, S.G. et al. (2011) Effect of Irrigation Intervals and Planting Patterns on Yield and Qualitative Traits of Forage Sorghum. In Advances in Environmental Biology , vol. 5, no. 10, pp. 3363–3368. SAMARAH, H. and ALQUDAH, A. (2009) Effects of late-terminal drought stress on seed germination and vigor of barley ( Hordeum vulgare L.). In Archives of Agronomy and Soil Science , in press. YOUNESI, O. and MORADI, A. (2009) The effect of water limitation in the field on sorghum seed germination and vigor. In Australian Journal of Basic and Applied Sciences , vol. 3, no. 2, pp. 1156– 1159.

We examined the effect of carbon metabolism inhibition, temperature, and water stress on the relationship between the linear electron transport and photosynthetic CO2 assimilation in sweet sorghum, Sorghum bicolor (L.) Moench. Carbon metabolism was inhibited either by removing CO2 from the air or by feeding glyceraldehyde to the leaves. Irrespective of the method used, the linear electron transport and photosynthesis were coordinately inhibited. However, when photosynthesis was totally inhibited, a residual electron transport between 20 and 35 µmol m-2 s-1 could be measured. The residual electron transport increased with increasing leaf temperature up to 38ºC and was higher in water-stressed leaves than in control leaves. Temperature affected photosynthesis in intact leaves. The optimal temperature for photosynthesis in control leaves was between 30 and 35ºC. The ratio between linear electron transport and photosynthesis showed a temperature dependency similar to that of photosynthesis. As a consequence, the electrons required to fix one mole of CO2 were 5.5 at suboptimal temperatures but were 6.5 at 30ºC. Our results indicate that the relationship between linear electron transport and photosynthesis is not perfectly steady in nature but is subject to transient changes. The observed changes in the linear electron transport were mostly related to changes in the efficiency of light trapping by open photosystem II (PSII) reaction centres, while the fractions of open PSII reaction centres were relatively constant during the experiment. Water stress severely reduced the photosynthetic CO2 assimilation of sweet sorghum leaves. The greater the water stress, the lower the temperature at which optimal photosynthesis was reached. The linear electron transport was coordinately inhibited by water stress but a residual electron transport was again found when photosynthesis was extremely reduced by water stress. Under water-stress conditions the fraction of PSII reaction centres in an open state was very low but constant, and the temperature dependent reduction of linear electron transport was caused by the reduction of the efficiency of energy capture of PSII reaction centres.

Low phosphorus availability and water stress are among the factors that have limited agricultural yield in soils of tropical regions. Based on that, an experiment was carried out to evaluate the effect of water stress and phosphorus levels on the nutrients accumulation in the shoots of sorghum plants (Sorghum bicolor (L.) Moench.), BR-304 mid-cycle cultivar. The experimental design was randomized blocks arranged in a 2x4 factorial scheme, being two water regimes (with and without water stress) and four phosphorus levels (0 mg dm-³, 50 mg dm-³, 100 mg dm-³, and 150 mg dm-3), with 4 replications. Plants were kept in pots (up to 9 kg of soil) and water stress was imposed 45 days after emergence, and persisted until growth stopped and apical leaves curled. Water stress reduced K accumulation and phosphorus fertilization increased the N, P, Ca, S, Mn, and Fe, and reduced the Zn absorption. The supply of P above 125 mg dm-3 reduced macronutrients accumulation in sorghum plants.KEY-WORDS: Sorghum bicolor (L.) Moench.; drought tolerance; mineral nutrition; forage plant.

یکی از مهم‌ترین راهبردهای گیاهان در پاسخ به تنش‌های غیر‌زنده از‌جمله خشکی، تجمع مواد محلول آلی سازگار است. به‌منظور بررسی اثر تنش خشکی بر عملکرد، اجزای عملکرد دانه و برخی صفات بیوشیمیایی در ژنوتیپ‌های سورگوم دانه‌ای، آزمایشی به‌صورت کرت‌های خرد‌شده در قالب طرح بلوک کامل تصادفی با سه تکرار در سال 1393 در مزرعه مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی خراسان جنوبی اجرا شد. تیمارهای تنش خشکی شامل آبیاری متداول (شاهد)، قطع آبیاری در مرحله رشد رویشی (مرحله رؤیت آخرین برگ به‌صورت لوله‌ای) و قطع آبیاری در مرحله رشد زایشی (50 درصد بوته‌ها در مرحله آغاز گلدهی) به‌عنوان عامل اصلی و 10 ژنوتیپ سورگوم دانه‌‌ای شامل: KGS29، MGS2،KGS33 ، سپیده، KGFS27،MGS5 ،KGFS5 ،KGFS17، KGFS13 و KGFS30 به‌عنوان عامل فرعی در نظر گرفته شدند. نتایج نشان داد که تنش خشکی تأثیر منفی معنی‌‌داری بر عملکرد دانه، وزن هزار دانه و تعداد دانه در پانیکول داشته است. ژنوتیپ‌های مورد‌مطالعه نیز از‌ نظر تمام صفات مورد‌ بررسی تفاوت آماری معنی‌دار داشتند که حاکی از وجود تنوع بالا در بین ژنوتیپ‌ها بود. تنش خشکی سبب کاهش محتوای کلروفیل و کاروتنوئیدها و افزایش محتوای کربوهیدرات‌های محلول و پرولین آزاد و نیز درصد قند ساقه (Brix) گردید. از‌ نظر عملکرد دانه ژنوتیپ KGFS13 با میانگین عملکرد 5060 کیلوگرم در هکتار و پس ‌از ‌آن ژنوتیپ KGFS17 قرار گرفت. مقایسه میانگین اثر متقابل ژنوتیپ و تنش خشکی از‌ نظر محتوای پرولین برگ نشان می‌دهد که ژنوتیپ KGSF17 در تیمار تنش خشکی متوسط، بالاترین میزان و ژنوتیپ‌‌های MGS5 و MGS2 در شرایط آبیاری متداول به‌طور مشترک کمترین میزان پرولین را دارا بودند. در‌مجموع نتایج نشان می‌دهد که تجمع پرولین و کربوهیدرات‌های محلول و درصد قند ساقه، در اثر تنش خشکی افزایش و رنگ‌دانه‌های فتوسنتزی کاهش پیدا می‌کند.

Grown in water-limited environments, sorghum (Sorghum bicolor (L.) Moench) is often exposed to water deficits of varying extent and timing. One of the impacts of water stress on sorghum production is lodging; however, there has been no published study quantifying the temporal and spatial frequency and severity of lodging in grain sorghum in Australia. In this study, we investigated the frequency and severity of lodging, using a dataset of 83 advanced yield-testing trials of the sorghum pre-breeding program grown in the seven major sorghum-production environments in Australia over 14 summer growing seasons. Lodging occurred in most production regions but with varying frequency and severity. Lodging was significantly greater in regions that were more prone to water stress (e.g. Central Highlands in Queensland) and significantly lower in regions that were less likely to suffer from water stress (e.g. Liverpool Plains in northern New South Wale) compared with the overall average across regions. The severity of lodging also varied across regions, with the most severe lodging (>20%) occurring in Central Highlands and Western Downs in Queensland. In addition, seasonal patterns of lodging frequency and severity were also observed. Over the 14 growing seasons, the frequency of lodging varied from 0% to 100%, with the most severe lodging (>20%) observed in 2005, 2016 and 2017. The Southern Oscillation Index explained 29% of the seasonal variation in lodging frequency. The findings of this study clearly support a link between lodging incidence and water stress across regions and seasons. Our data also showed that although there was a substantial turnover of commercial hybrids during the period of this study, the level of resistance to lodging appeared not to have improved. It is possible that this is due to plant breeders trading off improvements in lodging resistance to increase grain yield.

A study was conducted in Sudan (Africa) during the summer and winter seasons (2013 – 2014) at two locations: Shambat (normal soils) and Soba (salt affected soils). Nine maize (ZeamaysL.) and sorghum (Sorghum bicolor(L.) Moench) cultivars were studied under two watering regimes arranged in split plot experiment in randomized complete block design. The eight test-environments created by the combination of locations, seasons and watering regimes were used to investigate the effect of salt, water and heat stresses on forage yield and some related traits. The results showed that separate and combined stress factors significantly reduced forage yield. The greatest reduction in dry matter yield caused by one factor was shown by salt stress (29.6%) and the least reduction was caused by heat stress (3.9%). Water stress coupled with either heat or salt stress caused the greater reduction in yield (37.0%-43.3%) than the combination of the other factors. Full stress caused 53.8% yield reduction. Days to tasseling was significantly reduced by heat stress whereas water and salt stress showed no significant effect on tasseling duration. Full stress caused the greatest effect on days to tasseling. Plant height and stem diameter were significantly reduced by salt and water stress. Two hybrids kept top rank in yield through most abiotic stress levels showing resilience to unfavorable environments. All maize genotypes significantly outyielded the sorghum check under no heat stress (winter sowing) regardless the effect of salt and water stresses while the opposite is true under the heat stress (summer sowing). It was concluded that salt and water stress are the major abiotic stresses limiting forage maize production. Maize tolerate better reduction in temperature than dose sorghum while the latter tolerate better salt and water stresses than dose maize. Forage maize could be competitively grown during summer if water and salt stresses are avoided

The contribution of osmotic adjustment to grain yield in Sorghum bicolor (L.) subjected to water stress between anthesis and maturity was studied using six entries. Three of the entries (Goldrush, E57, and DK470) were selected for high osmotic adjustment and the other three (Texas 610SR, Texas 671, and SC 219-9-19-1) for low osmotic adjustment, and divided into early, intermediate and late maturity groups. Entries were either well watered, or subjected to a 50-day period of water shortage after anthesis following being well-watered prior to anthesis. Entries selected for high osmotic adjustment had mean values of osmotic adjustment at the end of the post-anthesis stress more than double those selected for low osmotic adjustment. The corresponding mean grain yield of entries with high osmotic adjustment were 24% higher than that of entries with low osmotic adjustment. The higher yield was due to both more and larger grains, and it was associated with higher harvest index and distribution index. At best, the difference in dry matter at maturity could explain only a few per cent of the difference in grain yield between entries with low and high osmotic adjustment. Water stress prior to anthesis (previous paper) reduced yield more than a post-anthesis stress of the same intensity. However, osmotic adjustment was equally effective in minimizing the reduction in grain yields in both stages. The use of osmotic adjustment as a selection trait in programs to improve the yield of grain sorghum is briefly discussed.

The contribution of osmotic adjustment to grain yield in Sorghum bicolor (L.) subjected to water stress before anthesis was studied using six entries. Three of the entries (Goldrush, E57, and DK470) were selected for high osmotic adjustment and the other three (Texas 6 1 OSR, Texas 67 1, and SC 219-9-1 9-1) for low osmotic adjustment, and divided into early, intermediate and late maturity groups. Entries were either well watered, or subjected to a 41-day period of water shortage prior to anthesis and well watered for the remainder of their growth. Entries selected for higher osmotic adjustment developed higher levels of osmotic adjustment during the pre-anthesis stress period than those selected for low osmotic adjustment in intermediate and late maturity groups, but not in the early group. However, the level of osmotic adjustment was not related to the maturity group, when water stress was imposed at the same developmental stage. Entries with high osmotic adjustment produced higher grain yields than those with low osmotic adjustment. The response varied from 15% for the mean of all maturity groups to 34% for the mean of intermediate and late groups, where there were significant differences in osmotic adjustment. The higher mean grain yield was due mainly to a larger grain number (19%). Even though entries with high osmotic adjustment bad a greater root length, soil water extraction and dry matter production during the pre-anthesis stress period, there was no significant difference in dry matter yield at physiological maturity between low and high osmotic adjustment groups. Consequently, the higher mean grain yield was related solely to a higher harvest index (27%), which was associated with a higher distribution index (25%) and a higher grain number (19%). A detailed analysis is given of the mechanisms by which osmotic adjustment contributed to grain yield in plants subjected to a pre-anthesis stress.

Background and AimsPhytolith studies are still facing numerous challenges regarding the available notions of Si absorption from soil and its deposition in aerial organs. This study shows how plant water availability affects the biosilica content and silicon isotopic composition of phytoliths in sorghum (Sorghum bicolor).MethodsPhytoliths were extracted from different plant parts of crops grown experimentally in lysimeters under water stress (WS) and well-watered (WW) conditions and analysed for silicon isotopic composition using femtosecond laser ablation multi-collector inductively coupled plasma-mass spectrometry (fsLA-MC-ICP-MS). This method provided precise isotope ratios of individual phytolith morphotypes.ResultsResults indicate that while Si isotopic composition largely reflects watering conditions, single morphotypes present major differences with Bulliform phytoliths demonstrating superior predictive capability for water availability. The distinct Si isotopic signatures observed in Bulliform, Elongate, and Stoma suggest that variations in Si fractionation among morphotypes could be linked to differences in Si absorption and deposition processes, likely mediated by water stress.ConclusionsOur findings align with prior research suggesting that water stress affects Si uptake, potentially altering the Si-water movement relationship. The significant variability in the isotopic data measured indicates the potential involvement of additional environmental, and consequently physiological factors influencing silicon isotope composition in phytoliths, especially Bulliform, which we suggest should be the focus of future research. Our model offers a solid foundation for research in several fields, from agronomic studies aimed at using Si to improve drought-resistance, to palaeoenvironmental and archaeological studies aimed at reconstructing past climate change and human–environment interactions.

In semiarid regions of the Mediterranean basin, water and salinity stresses restrict crop establishment. The effects of salt and water stress on seed germination and early embryo growth (radicle and shoot growth) were investigated in laboratory in two cultivars of sweet sorghum [Sorghum bicolor (L.) Moench] – cv. ‘90‐5‐2′ and cv. ‘Keller’ – to verify how these stresses may limit crop growth during the very early stages of growing season. Six water potentials (ψ) of the imbibition solution (from 0 to −1.0 MPa) in NaCl or polyethylene glycol (PEG) for salt and water stress tests, respectively, were studied. Daily germination was recorded, and radicle and shoot lengths and dry weights (DWs) were measured 2 days after initial germination. Seed germination was reduced (8–30% lower than control) by water stress at ψ <−0.6 MPa and was delayed (approx. +10 h) already at −0.4 MPa. Salt stress only prolonged germination time. Shoot and root growth was adversely affected by water stress (PEG), whereas the effect of salt stress was less relevant. Cv. ‘90‐5‐2’ was less sensitive than cv. ‘Keller’ to both stresses. These cultivars exhibited a greater sensitivity to abiotic stresses in terms of root and shoot growth; therefore, other parameters beside germination, such as early embryo growth rate, may help in evaluating sorghum lines for adaptation to semi‐arid areas.

Three varieties (Segaolane, Mahube and Phofu) of sorghum (Sorghum bicolor L. Moench) that were selected in Botswana, were water-stressed at the vegetative, booting and flowering stages in a pot experiment under glasshouse conditions. Stomatal conductance was reduced by water stress but at the vegetative stage all varieties were able to recover to their pre-stress conductance levels. Total leaf area, effective (green) leaf area, specific leaf weight and specific leaf area all decreased with stress while root/shoot ratio increased. Grain yields were significantly (p < 0.05) lowered by stress, especially when this was applied at the booting stage. Although varietal differences in yield were not significant, based on overall performance the older Segaolane appears superior to the more recently developed varieties Phofu and Mahube, in conditions of hydrological unpredictability and intermittent water stress.

Accurate and reliable gene expression data from qPCR depends on stable reference gene expression for potential gene functional analyses. In this study, 15 reference genes were selected and analyzed in various sample sets including abiotic stress treatments (salt, cold, water stress, heat, and abscisic acid) and tissues (leaves, roots, seedlings, panicle, and mature seeds). Statistical tools, including geNorm, NormFinder and RefFinder, were utilized to assess the suitability of reference genes based on their stability rankings for various sample groups. For abiotic stress, PP2A and CYP were identified as the most stable genes. In contrast, EIF4α was the most stable in the tissue sample set, followed by PP2A; PP2A was the most stable in all the sample set, followed by EIF4α. GAPDH, and UBC1 were the least stably expressed in the tissue and all the sample sets. These results also indicated that the use of two candidate reference genes would be sufficient for the optimization of normalization studies. To further verify the suitability of these genes for use as reference genes, SbHSF5 and SbHSF13 gene expression levels were normalized using the most and least stable sorghum reference genes in root and water stressed-leaf tissues of five sorghum varieties. This is the first systematic study of the selection of the most stable reference genes for qPCR-related assays in Sorghum bicolor that will potentially benefit future gene expression studies in sorghum and other closely related species.

Mauritania is a Sahelian country highly exposed to climate change. Its territory is subject to successive variations in agricultural production caused by several factors, including low and irregular rainfall; deteriorating climatic conditions, and widespread desertification. In addition to these phenomena, which limit agricultural production in Mauritania, yields could fall further as a result of global warming and climate change, which aggravate inappropriate agricultural practices such as over-exploitation of the land, insufficient irrigation, and the advance of the desert. Drought is one of the major constraints that considerably affects the growth and development of plants and limits crop productivity by inducing osmotic stress. It is in this context that this study is being carried out on a set of local accessions of Mauritanian sorghum (Sorghum bicolor) to explore the phenotypic variability of this heritage and to characterize agro-morphologically this resource under water stress. Morphological, agronomic, and phenological parameters were studied during the project. Analysis of variance showed a highly significant effect of varieties on all morphological parameters. The Rhaye (Sidi nielbe) and Nienikou accessions are the earliest, with a heading period of 45 days, while the Nébané and Bechne Aarre varieties are the latest, with a heading period of around 80 days. The Nieniko, Leghvere, Rhaye (Sidi nielbe), and coumbe Nday ecotypes are the best in terms of yield parameters. The Taghalit lhamra, Taghalit lbeyda, Ghilé, Ras louche, and Beyke ecotypes performed similarly under rainfed and irrigated conditions in terms of vegetative growth.

Sorghum [Sorghum bicolor (L.)] is one of the most drought tolerant cereal and many studies have been done to understand the mechanisms involved in this process. In this work, we evaluated in the greenhouse the effects of different levels of water stress on the ecophysiological characteristics and accumulation of soluble sugars in two contrasting sorghum [Sorghum bicolor (L.) Moench] inbred lines for drought tolerance: 9910032 (tolerant) and 9618158 (sensitive). Water stress was imposed in both genotypes at pre-flowering growth stage for two different time exposure: mild (6 days of drought); severe (12 days). Recovery treatments for each drought treatment were also done at six days after the stress. Sensitive and tolerant genotypes showed lower stomatal conductance and leaf water potential for all types of stress when compared to irrigated treatments. An increase in total soluble sugar content was observed in leafs of the two sorghum genotypes however higher in the tolerant line. Overall, the genotype 9910032 presented higher photosynthetic rate and grain yield in relation to the sensitive genotype 9615818, in the same water condition. These results indicated that sugar content is modified under water deficit conditions indicating that if might be involved in plant protection.

Corn (Zea mays L.) and sorghum (Sorghum bicolor (L.) Moench) yield and nutritional quality affected by drought stress