Reaction of some rapeseed (Brassica napus L.) genotypes to different drought stress levels during germination and seedling growth stages☆

Drought is a major abiotic stress that affects seed germination and plant growth in arid and semi-arid regions. Rapeseed is an oilseed crop adapted to Mediterranean area; however, it is reported that it is sensitive to water stress occurring during seed germination. In this study, we investigated how seed germination and early seedling growth of six rapeseed genotypes were influenced by different water stress levels. In addition to the control (absence of drought stress), three drought levels were simulated using three osmotic potentials of polyethylene glycol (PEG-6000), −9, −10 and −11 bars. A completely randomized design with three replications was used for this experiment. Germination percentage (GP), shoot length (SL), root length (RL), shoot elongation rate (SER) and root elongation rate (RER) were determined to evaluate the genotypes response to PEG-induced drought stress. Results showed drought stress, genotype and interaction stress × genotype had a significant effect on the studied parameters. GP decreased with the increase in stress level. The genotype ‛Nap9’ was the most interesting, having the highest GP values, namely 63.33, 62.67 and 28% under the stress levels −9, −10 and −11 bars, respectively. The genotype ‛H2M-5’, which ranked second with respect to this parameter, was statistically comparable to ‛Nap9’. Also, SL, RL, SER and RER decreased with the increase in drought stress level. However, the studied genotypes reacted differently to various water stress levels. Once again, the genotype ‛H2M-5’ exhibited the highest average RL and RER under all drought levels. Particularly, for severe drought conditions (−11 bars), ‛H2M-5’ had an average RL of 1.54 cm and RER of 0.36 cm/d. Field evaluation under controlled conditions is needed to confirm findings of the present experiment. The mutant ‛H2M-5’ could be a valuable and promising germplasm for developing a performant and adapted variety to be designed for harsh environments particularly characterized by early drought coinciding with germination and seedling growth stages

Reaction of some rapeseed (

Drought is a major abiotic stress that affects seed germination and plant growth in arid and semi-arid regions. Rapeseed is an oilseed crop adapted to Mediterranean area; however, it is reported that it is sensitive to water stress occurring during seed germination. In this study, we investigated how seed germination and early seedling growth of six rapeseed genotypes were influenced by different water stress levels. In addition to the control (absence of drought stress), three drought levels were simulated using three osmotic potentials of polyethylene glycol (PEG-6000), −9, −10 and −11 bars. A completely randomized design with three replications was used for this experiment. Germination percentage (GP), shoot length (SL), root length (RL), shoot elongation rate (SER) and root elongation rate (RER) were determined to evaluate the genotypes response to PEG-induced drought stress. Results showed drought stress, genotype and interaction stress × genotype had a significant effect on the studied parameters. GP decreased with the increase in stress level. The genotype ‛Nap9’ was the most interesting, having the highest GP values, namely 63.33, 62.67 and 28% under the stress levels −9, −10 and −11 bars, respectively. The genotype ‛H2M-5’, which ranked second with respect to this parameter, was statistically comparable to ‛Nap9’. Also, SL, RL, SER and RER decreased with the increase in drought stress level. However, the studied genotypes reacted differently to various water stress levels. Once again, the genotype ‛H2M-5’ exhibited the highest average RL and RER under all drought levels. Particularly, for severe drought conditions (−11 bars), ‛H2M-5’ had an average RL of 1.54 cm and RER of 0.36 cm/d. Field evaluation under controlled conditions is needed to confirm findings of the present experiment. The mutant ‛H2M-5’ could be a valuable and promising germplasm for developing a performant and adapted variety to be designed for harsh environments particularly characterized by early drought coinciding with germination and seedling growth stages

Comparative field studies of biochemical and agro-physiological parameters in semi-arid zone with rainfall Moroccan climate of durum wheat

Durum wheat production is highly unpredictable throughout the year because of uncertain rainfall and frequent dry spells and it is absolutely necessary to characterize the impact of drought on grain yield. The objective in this research is to carry out a comparative analysis of biochemical and physiological responses and production parameters of durum wheat (Triticum durum) in semi-arid zone with rainfall in Morocco's climates. Thirteen durum wheat genotypes selected at INRA-Morocco and three control varieties were evaluated under Moroccan rainfed conditions for two growing seasons (2019/20 and 2020/21). The INRA-Morocco-Douyet Fez experimental field site was where the trials were conducted (34°2 N, 5°W, 416 m). Different parameters were studied. Five physiological, four agronomical and one biochemical trait are measured in this study: leaf area, leaf temperature, relative water content, chlorophyll content, proline, yield and yield components. Decreased rainfall significantly increased proline content, leaf temperature and decreased leaf area, grain yield, chlorophyll and relative water content (P < 0.01). Based on these results, field-induced rainfall variations resulted in inconsistencies in the response of the assessed traits to drought-related interactions between both growing seasons (2020–2021) in order to identify stable, high-yielding genotypes in the presence and absence of rainfall, which requires a strong association of drought-related traits

Water stress effect on durum wheat (Triticum durum Desf.) advanced lines at flowering stage under controlled conditions

Drought stress is a key factor affecting Morocco's agricultural productivity. In order to adapt to climate change, it is crucial to select new genotypes which may be slightly but not significantly less efficient. Durum wheat (Triticum durum Desf.) is one of the most important and cereal crops that are impacted by drought. The objective of this research was to assess the performance of 16 durum wheat genotypes to drought stress. From the beginning of flowering stage until the beginning of seed maturity, three levels of water treatment were applied, corresponding to 100%, 66% and 33% of field capacity. Three agro-morphological, five physiological and three biochemical traits were investigated in those genotypes grown under controlled greenhouse conditions over two years (2020 and 2021), by following completely randomized design (CRD) with three replications. The results showed that stomatal conductance, relative water content, leaf area, leaf temperature, SPAD values, proline, soluble sugars, glycine betaine and yield traits were significantly (p 12 g; p 50%; p 50 SPAD; p 0.6 mol m-2s-1; p < 0.001). Therefore, these lines could be selected as relevant and valuable germplasms to be used in durum wheat breeding programs aiming to develop drought-tolerant and high-yielding varieties. High relative water content and stomatal conductance along with low leaf temperature can be taken as selection indices in this breeding program

Variation in rapeseed genotype’s reaction to drought during flowering and identification of tolerant-genotypes selection index

Rapeseed (Brassica napus L.) crop is particularly susceptible to drought at the flowering stage. This study was conducted to (i) assess four genotypes under contrasting water conditions for their reaction to drought and (ii) determine the traits associated with tolerance and yield stability. The experiment was carried out in pots during two cropping years under greenhouse-controlled conditions. From the flowering stage to early seed maturity, the four genotypes were evaluated under two levels of water stress T2 (66% of T1) and T3 (33% of T1), in addition to full irrigation as the control water regime (T1). Results indicated significant effects of genotype, water regime and their interaction on all measured parameters. The genotype ‘Nap9’ was the best regarding seed yield and oil content under the two levels of water stress and for both years. It also exhibited higher root length and higher leaf relative water content than the other genotypes. Therefore, it may be recommended as a valuable germplasm in rapeseed breeding programs for drought tolerance. High branching combined with high leaf relative water content could be a relevant and valuable selection index for this breeding program