Plant growth promoting endophytic bacteria Burkholderia phytofirmans PsJN was used to investigate the potential to ameliorate the effects of drought stress on growth, physiology and yield of wheat (Triticum aestivum L.) under natural field conditions. Inoculated and uninoculated (control) seeds of wheat cultivar Sahar 2006 was sown in the field. The plants were exposed to drought stress at different stages of growth (tillering stage and flowering stage) by skipping the respective irrigation. The results showed that drought stress adversely affected the physiological, biochemical and growth parameters of wheat seedlings. It decreased the CO2 assimilation, stomatal conductance, relative water content, transpiration rate and chlorophyll contents in wheat. Inoculation of wheat with PsJN significantly diluted the adverse effects of drought on relative water contents and CO2 assimilation rate thus improving the photosynthetic rate, water use efficiency and chlorophyll content over the uninoculated control. Grain yield was also decreased when plants were exposed to drought stress at the tillering and flowering stage, but inoculation resulted in better grain yield (up to 21 and 18 % higher, respectively) than the respective uninoculated control. Similarly, inoculation improved the ionic balance, antioxidant levels, and also increased the nitrogen, phosphorus, potassium and protein concentration in the grains of wheat. The results suggested that B. phytofirmans strain PsJN could be effectively used to improve the growth, physiology and quality of wheat under drought conditions. 相似文献
A drought event can cause yield loss or entire crops to fail. In order to study the effects of continuous drought on physiological characteristics, yield, and water use efficiency (WUE) of winter wheat (Triticum aestivum L.), the variety “Zhoumai 22” was grown in controlled water conditions of the pot-planted winter wheat under a mobile rainout shelter. Foot planting and safe wintering were used to evaluate, winter wheat under different drought conditions, including light, moderate and severe drought at the jointing, heading, and filling stages. The soil water content was controlled at 60–70%, 50–60%, or 40–50% of field capacity. Experimental trials included 3 pre-anthesis drought hardening, 3 three-stage continuous drought, and 1 test control conditions. Under drought stress conditions, winter wheat leaf water potential, soil plant analysis development (SPAD), photosynthesis parameters, and yield declined due to pre-anthesis drought hardening. And the degree of decline: continuous drought > pre-anthesis drought hardening. Changes in the post-anthesis photosynthetic capacity of winter wheat were mainly related to the pre-anthesis drought level, rather than post-anthesis rehydration. The threshold of non-stomata limiting factors caused by photosynthesis at the filling stage is 40–50%FC, while comprehensive yield and WUE affected, the yield in severe drought treatments was the most significant, B3C3 and B3C3G3 decreased by 55.68% and 55.88%, respectively. Pre-anthesis drought was the main reason for the decreased crop yield. Thus, severe drought should be avoided during planting, while pre-anthesis light drought is a suitable choice for water-saving and crop production, as proper pre-anthesis drought hardening (60–70% FC) is feasible and effective. 相似文献
Longer and more intense heat and drought stresses will occur in terrestrial ecosystems in the future. Although the effects of individual heat or drought stress on wheat plants have been largely explored, the regulatory effect of nitrogen (N) on winter wheat under heat, drought, and combined stresses and whether N alleviates damage to wheat plants caused by these stresses remain unclear. Therefore, the objective of the present study was to investigate the growth, photosynthesis, antioxidant enzyme and N metabolism-related enzyme activity, cell membrane system, osmoregulatory substance, and yield responses to heat, drought, and combined stresses in wheat plants and to clarify the regulatory effects of N on the growth, physiological and biochemical characteristics, and yield of wheat plants under stress conditions. The results showed that wheat plant exposure to individual heat or drought stress reduced photosynthesis and N metabolism-related enzyme activities and increased antioxidant enzyme activities, electrolyte leakage (EL), and the contents of MDA (malondialdehyde) and O2? (superoxide anion). The above parameters showed typical superposition effects under combined stress. Under individual heat or drought stress, wheat plants treated with a medium (N2) or high (N3) N supply maintained higher photosynthesis and N metabolism-related enzyme activities than did those treated with a low N supply (N1). Enhanced heat and drought tolerance in wheat plants under an appropriate N supply may be attributed to improved antioxidant capacity, as exemplified by increased activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione reductase (GR) and ascorbate peroxidase (APX), and to enhanced osmoregulation capacity, as signified by increased contents of soluble sugar (SS), soluble protein (SP), and proline (Pro). Variable importance in projection (VIP) analysis indicated that efficient SOD, POD, CAT, and GR activities and an increased Pro content had superior potential to alleviate heat, drought, and combined stress stresses in wheat plants, and the improvements in growth and grain yield in wheat plants further confirmed the oxidative stress alleviation and stress tolerance enhancement. However, positive effects of N on wheat growth and grain yield under combined stress were usually observed under a low N supply. These results may facilitate future research on the effects of N fertilizer on the stress resistance of winter wheat.
Drought is one of the major abiotic stresses restricting the yield of wheat (Triticum aestivum L.). Breeding wheat varieties with drought tolerance is an effective and durable way to fight against drought. Here we reported introduction of AtHDG11 into wheat via Agrobacterium-mediated transformation and analyzed the morphological and physiological characteristics of T2 generation transgenic lines under drought stress. With drought treatment for 30 days, transgenic plants showed significantly improved drought tolerance. Compared with controls, the transgenic lines displayed lower stomatal density, lower water loss rate, more proline accumulation and increased activities of catalase and superoxide dismutase. Without irrigation after booting stage, the photosynthetic parameters, such as net photosynthesis rate, water use efficiency and efficiency of excitation energy, were increased in transgenic lines, while transpiration rate was decreased. Moreover, the kernel yield of transgenic lines was also improved under drought condition. Taken together, our data demonstrate that AtHDG11 has great potential in genetic improvement of drought tolerance of wheat. 相似文献
Osmotic adjustment (OA) and cellular compatible solute accumulation are widely recognized to have a role in plant adaptation to dehydration mainly through turgor maintenance and the protection of specific cellular functions by defined solutes. At the same time, there has been an ongoing trickle of skepticism in the literature about the role of OA in supporting crop yield under drought stress. Contrarian reviews argued that OA did not sustain turgor or that it served mainly for plant survival rather than productivity. This critical review examined 26 published studies where OA was compared with yield under drought stress in variable genotypes of 12 crops, namely, barley, wheat, maize, sorghum, chickpea, pea, pigeon pea, soybean, canola, mustard, castor bean and sunflower. Over all crops a positive and significant association between OA and yield under drought stress were found in 24 out of 26 cases. Considering that it is generally difficult to find a singular plant trait responsible for yield advantage of numerous crops under different drought stress conditions, this evidence is no less than remarkable as proof that OA sustains crop yield under drought stress. 相似文献
The effects of soil water regime and wheat cultivar, differing in drought tolerance with respect to root respiration and grain
yield, were investigated in a greenhouse experiment. Two spring wheat (Triticum aestivum) cultivars, a drought sensitive (Longchun 8139-2) and drought tolerant (Dingxi 24) were grown in PVC tubes (120 cm in length and 10 cm in diameter) under an automatic rain-shelter. Plants were subjected
to three soil moisture regimes: (1) well-watered control (85% field water capacity, FWC); (2) moderate drought stress (50%
FWC) and (3) severe drought stress (30% FWC). The aim was to study the influence of root respiration on grain yield under
soil drying conditions. In the experiment, severe drought stress significantly (p < 0.05) reduced shoot and root biomass, photosynthesis and root respiration rate for both cultivars, but the extent of the
decreases was greater for Dingxi 24 compared to that for Longchun 8139-2. Compared with Dingxi 24, 0.04 and 0.07 mg glucose m−2 s−1 of additional energy, equivalent to 0.78 and 1.43 J m−2 s−1, was used for water absorption by Longchun 8139-2 under moderate and severe drought stress, respectively. Although the grain yield of both cultivars decreased with declining
soil moisture, loss was greater in Longchun 8139-2 than in Dingxi 24, especially under severe drought stress. The drought tolerance cultivar (Dingxi 24), had a higher biomass and metabolic activity under severe drought stress compared to the sensitive cultivar (Longchun 8139-2), which resulted in further limitation of grain yield. Results show that root respiration, carbohydrates allocation (root:shoot
ratio) and grain yield were closely related to soil water status and wheat cultivar. Reductions in root respiration and root
biomass under severe soil drying can improve drought tolerant wheat growth and physiological activity during soil drying and
improve grain yield, and hence should be advantageous over a drought sensitive cultivar in arid regions. 相似文献
A drought event can cause entire crops to fail or yield loss. In order to
study the effects of continuous drought on photosynthetic characteristics, yield,
and water use efficiency (WUE) of winter wheat (Triticum aestivum L.), the winter wheat variety “Aikang 58” was selected as test material with controlling the
water of the pot-planted winter wheat under a mobile rainout shelter. Based on
foot planting and safe wintering, winter wheat was evaluated under different
drought conditions, including light, moderate and severe drought at the jointing
(B), heading (C), and filling (G) stages. The soil water content was controlled
in a range of 60% to 70%, 50% to 60%, and 40% to 50% of the field capacity,
respectively. In the experiment, there were 9 single-stage droughts, 3 three-stage
droughts, and 1 test control (totaling 13 trials). The results are as follows: Under a
single-stage drought, the change of net photosynthetic rate (Pn) and stomatal conductance (Gs) have similar trends, and they both decrease significantly with the
severity of the drought. Under three-stage continuous droughts, the change curve
of Gs shows a constant downward trend; the change curve of Pn showed a “valley
shape,” and the minimum value of Pn appeared at the heading stage. All droughts
will reduce the yield of winter wheat. Under the three-stage continuous drought
conditions, except for light drought, moderate drought and severe drought will
cause significant yield reduction, mainly due to lack of water at the jointing
and heading stages. Continuous drought will reduce the WUE, and the difference
will reach a significant level under moderate and severe drought. The present
results suggested that when water resources are scarce, it is a better irrigation
model to save water and achieve high grain yield by applying appropriate water
stress (60%–70% FC) during the critical growth period of winter wheat. 相似文献