Aphids in a changing world: testing the plant stress,plant vigour and pulsed stress hypotheses

• 1 The plant stress, plant vigour and pulsed stress hypotheses describe the relationships between drought stress, plant quality and herbivore performance. We used an aphid‐Brassica system to test these hypotheses under different drought treatments.
• 2 The quantity of water added per plant/week was 75%, 50% and 25% of the control (unstressed) water regime for low, medium and high drought stress, respectively, and 50% applied fortnightly for pulsed drought stress. The performance of a ‘senescence’ (generalist) and a ‘flush’ feeder (specialist) aphid species and host plant quality were assessed.
• 3 Drought treatments had a similar effect on the fecundity and intrinsic rate of increase of both aphid species. Aphid performance on unstressed and highly drought‐stressed plants was significantly lower compared with medium drought stress. On average, 20% greater fecundity and 40% greater intrinsic rates of increase were recorded for both aphid species at medium drought stress compared with unstressed plants.
• 4 Plant biomass and relative water contents were significantly greater for unstressed plants compared with high and pulsed drought treatments. Foliar nitrogen concentration was significantly greater in the high drought stress and pulsed treatments, and the dominant glucosinolate (glucobrassicin) concentration was significantly greater in drought stress treatments.
• 5 The present study supports the plant stress hypothesis, although the plant vigour and pulsed stress hypotheses are not supported by our data. The implications of these findings for plant–herbivore interactions under changing environmental conditions are discussed.

     

The plant vigour hypothesis revisited – how is browsing by ungulates and elephant related to woody species growth rate?

The way herbivores select what to eat is of considerable practical and theoretical interest, and has given rise to different theories and hypotheses. The plant vigour hypothesis predicts that herbivores feed preferentially on vigorous, i.e., large and/or fast-growing plants or plant parts. These predictions have previously primarily been tested on variation within plant species. Here we test whether differences in vigour among plant species in the same environment can explain differences in herbivore attack. We studied variation in browsing pressure by a guild of large herbivores on different woody species in an African savanna ecosystem. Shoot growth rate, annual shoot length, basal shoot diameter and annual shoot volume of 14 woody plant species were measured in the field. Plant species’ shoot vigour represented by the first PCA axis scores generated from the four shoot variables were then related to browsing pressure (% utilisation) on each of the species by native ungulates and elephant. Nutrient and fibre concentrations and tannin activity were also determined for the 14 woody plant species. We found ungulate browsing pressure to show a unimodal relationship with plant species’ shoot vigour. The heaviest browsing pressure was on plant species with shoots of intermediate vigour. We suggest that species with less vigorous shoots had low nutrient and high fibre concentrations and offered small bite sizes, whereas species with vigorous shoots had high nutrient concentrations but larger shoot diameters than the bite diameters of browsing ungulates. Elephant browsing pressure was not related to plant species’ shoot vigour.     

Variation in insect herbivory across a salt marsh tidal gradient influences plant survival and distribution

Herbivore damage and impact on plants often varies spatially across environmental gradients. Although such variation has been hypothesized to influence plant distribution, few quantitative evaluations exist. In this study I evaluated patterns of insect herbivory on an annual forb, Atriplex patula var. hastata, across a salt marsh tidal gradient, and performed experiments to examine potential causes and consequences of variation in herbivory. Damage to plants was generally twice as great at mid-tidal elevations, which are more frequently inundated, than at higher, less stressful, elevations at five of six surveyed sites. Field herbivore assays and herbivore preference experiments eliminated the hypothesis that plant damage was mediated by herbivore response to differences in host plants across the gradient. Alternately, greater herbivore densities in the mid-marsh, where densities of an alternate host plant (Salicornia europaea) were high, were associated with greater levels of herbivory on Atriplex, suggesting spillover effects. The effect of insect herbivores on host plant performance varied between the two sites studied more intensively. Where overall herbivore damage to plants was low, herbivory had no detectable effect on plant survival or seed production, and plant performance did not significantly differ between zones. However, where herbivore damage was high, herbivores dramatically reduced both plant survival (>50%) and fruit production (40-70%), and their effects were stronger in the harsher mid-marsh than the high marsh. Thus herbivores likely play a role in maintaining lower Atriplex densities in mid-marsh. Overall, these results suggest that variation in herbivore pressure can be an important determinant of patterns of plant abundance across environmental gradients.     

Influence of previous frost damage on tree growth and insect herbivory of Eucalyptus globulus globulus

The plant stress hypothesis suggests that some herbivores favour stressed plants, whereas the plant vigour hypothesis proposes that other herbivores prefer vigorous plants. The effects of a prior stress, that of frost damage, were examined on the subsequent growth of Eucalyptus globulus globulus and on the response of insect herbivores. Frost damage affected tree growth by reducing new leaf area and increasing specific leaf area (SLA). However, herbivore abundance was not affected by prior frost damage. Two feeding trials using Anoplognathus chloropyrus and Hyalarcta huebneri and a morphometric study of Ctenarytaina eucalypti were conducted to assess the performance of herbivores on trees that had suffered more or less frost damage. Consumption by A. chloropyrus and H. huebneri was unaffected by foliage origin (damaged versus healthy). Hyalarcta huebneri grew faster when fed leaves from previously damaged trees, and C. eucalypti from previously damaged trees were larger than those from healthy trees. Enhanced insect performance on frost damaged plants may have resulted from the high specific leaf area (most likely thinner) leaves. The herbivore abundance data did not support the hypothesis that previously frost damaged plants are preferred by insects. However, increased growth of H. huebneri and larger body size of C. eucalypti on damaged trees indicates that previously stressed trees may produce leaves of higher nutritional value.     

Drought and Root Herbivory Interact to Alter the Response of Above-Ground Parasitoids to Aphid Infested Plants and Associated Plant Volatile Signals

Multitrophic interactions are likely to be altered by climate change but there is little empirical evidence relating the responses of herbivores and parasitoids to abiotic factors. Here we investigated the effects of drought on an above/below-ground system comprising a generalist and a specialist aphid species (foliar herbivores), their parasitoids, and a dipteran species (root herbivore).We tested the hypotheses that: (1) high levels of drought stress and below-ground herbivory interact to reduce the performance of parasitoids developing in aphids; (2) drought stress and root herbivory change the profile of volatile organic chemicals (VOCs) emitted by the host plant; (3) parasitoids avoid ovipositing in aphids feeding on plants under drought stress and root herbivory. We examined the effect of drought, with and without root herbivory, on the olfactory response of parasitoids (preference), plant volatile emissions, parasitism success (performance), and the effect of drought on root herbivory. Under drought, percentage parasitism of aphids was reduced by about 40–55% compared with well watered plants. There was a significant interaction between drought and root herbivory on the efficacy of the two parasitoid species, drought stress partially reversing the negative effect of root herbivory on percent parasitism. In the absence of drought, root herbivory significantly reduced the performance (e.g. fecundity) of both parasitoid species developing in foliar herbivores. Plant emissions of VOCs were reduced by drought and root herbivores, and in olfactometer experiments parasitoids preferred the odour from well-watered plants compared with other treatments. The present work demonstrates that drought stress can change the outcome of interactions between herbivores feeding above- and below-ground and their parasitoids, mediated by changes in the chemical signals from plants to parasitoids. This provides a new insight into how the structure of terrestrial communities may be affected by drought.     

The effects of drought and herbivory on plant–herbivore interactions across 16 soybean genotypes in a field experiment

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Stress magnitude matters: different intensities of pulsed water stress produce non‐monotonic resistance responses of host plants to insect herbivores

Abstract 1. Water stress may increase or reduce the suitability of plants for herbivores. The recently proposed ‘pulsed stress hypothesis’ suggests consideration of stress phenology (pulsed vs. continuous stress) to explain these conflicting effects of plant water stress on herbivore performance. 2. This hypothesis was tested for the effect of differing stress intensity on performance and preference of insect herbivores belonging to different feeding guilds, namely leaf‐chewing insects (Spodoptera littoralis caterpillars) and phloem‐feeding insects (Aphis pomi aphids), on apple plants (Malus domestica). The plants were non‐stressed or exposed to a low or high intensity of pulsed water stress. 3. Plant responses to the different stress levels were generally monotonic. Growth, stomatal conductance (g_s), leaf water, and old‐leaf nitrogen concentration decreased, whereas young‐leaf nitrogen concentration and leaf mass per area (LMA) increased with increasing stress intensity. The stable isotope composition of foliar carbon (δ¹³C) responded non‐monotonically to the drought treatments. The δ¹³C values were highest in low‐stress plants, intermediate in high‐stress plants, and lowest in non‐stressed plants. 4. The preference and performance responses of the caterpillars were also non‐monotonic. Non‐stressed plants were intermediately, low‐stress plants least, and high‐stress plants most attractive or suitable. Aphid population growth was highest on non‐stressed plants and lowest on low‐stress plants. 5. The results highlight the importance of water stress intensity for the outcome of interactions between herbivores and drought‐affected plants. They show that pulsed water stress may enhance or reduce insect herbivore performance and plant resistance, depending on stress intensity.     

Not all droughts are created equal? The effects of stress severity on insect herbivore abundance

Predicting interactions between drought and plant–insect interactions has been a challenge. Currently, we are unable to accurately predict herbivore abundance on stressed plants despite over 500 publications and half a dozen formal hypotheses. With drought predicted to increase in severity with climate change, determining herbivore abundance on stressed plants is critical for continued agricultural and natural system management. During drought, plants increase concentrations of nutrients and also suffer from water loss. Many empirical studies test drought on plants using severe continuous stress, but studies suggest drought may benefit herbivores when it is intermittent (pulsed). In our study, we tested intermittent and severe stress on herbivore and arthropod abundance in a cotton agro-ecosystem. Our goal was to determine how these types of drought influence herbivore abundance on stressed plants and the relationship between herbivore abundance and stress-related nutrients. We found that intermittent and severe water-deficit stress had different effects on insect herbivores, signifying that drought severity influences herbivore abundance. Piercing–sucking herbivores such as thrips, stink bugs, and leafhoppers were more abundant on intermittently stressed plants than on severely stressed plants. Drought did not significantly affect chewing herbivores, and their abundance was inconsistent on stressed and well-watered plants. Furthermore, nutrient concentrations were similar between stressed and unstressed plants, but herbivore abundance was greater on intermittently stressed plants, suggesting that other physiological characteristics of stressed plants and herbivore feeding ecology must be considered. Our study suggests that the drought severity must be considered when predicting herbivore abundance on stressed plants.     

Plant water stress and previous herbivore damage affect insect performance

1. Short‐term changes in plant resistance traits can be affected by abiotic factors or damage by herbivores, although how the combined effects of abiotic factors and previous damage affect subsequent insect larval development is not well understood. 2. Complementary glasshouse and field experiments were conducted to evaluate whether plant water stress and previous herbivore damage influenced monarch (Danaus plexippus) larval development on common milkweed, Asclepias syriaca. 3. In the glasshouse, water stress altered a suite of A. syriaca functional traits but did not affect nutrient content, whereas herbivore damage increased leaf nitrogen (N) and reduced the carbon:nitrogen (C:N) ratio. A bioassay experiment showed that monarch larval survival was lower on well‐watered plants that were previously damaged by monarch larva than on damaged and drought‐stressed plants. Bioassay larvae consumed less leaf tissue of previously damaged plants, whereas monarch larval mass was affected additively by water stress and previous damage, after correcting for the amount of leaf tissue consumed. 4. In a 2‐year field experiment, monarch larval performance was higher on previously damaged A. syriaca plants that received experimentally reduced rainfall, relative to plants receiving ambient rainfall. 5. Collectively, these results from glasshouse and field experiments suggest that insect performance was highest on previously damaged plants under water stress and highlight the additive and interactive roles of abiotic and biotic factors on herbivore performance.     

Plant traits shape soil legacy effects on individual plant–insect interactions

Plant-mediated soil legacy effects can be important determinants of the performance of plants and their aboveground insect herbivores, but, soil legacy effects on plant–insect interactions have been tested for only a limited number of host plant species and soils. Here, we tested the performance of a polyphagous aboveground herbivore, caterpillars of the cabbage moth Mamestra brassicae, on twelve host plant species that were grown on a set of soils conditioned by each of these twelve species. We tested how growth rate (fast- or slow-growing) and functional type (grass or forb) of the plant species that conditioned the soil and of the responding host plant species growing in those soils affect the response of insect herbivores to conditioned soils. Our results show that plants and insect herbivores had lower biomass in soils that were conditioned by fast-growing forbs than in soils conditioned by slow-growing forbs. In soils conditioned by grasses, growth rate of the conditioning plant had the opposite effect, i.e. plants and herbivores had higher biomass in soils conditioned by fast-growing grasses, than in soils conditioned by slow-growing grasses. We show that the response of aboveground insects to soil legacy effects is strongly positively correlated with the response of the host plant species, indicating that plant vigour may explain these relationships. We provide evidence that soil communities can play an important role in shaping plant–insect interactions aboveground. Our results further emphasize the important and interactive role of the conditioning and the response plant in mediating soil–plant–insect interactions.     

Drought alters interactions between root and foliar herbivores

Drought can alter plant quality and the strength of trophic interactions between herbivore groups, and is likely to increase in occurrence and severity under climate change. We hypothesized that changes in plant chemistry due to root herbivory and drought stress would affect the performance of a generalist and a specialist aphid species feeding on a Brassica plant. High drought stress increased the negative effect of root herbivory on the performance of both aphid species (30 % decrease in fecundity and 15 % reduction in intrinsic rate of increase). Aphid performance was greatest at moderate drought stress, though the two species differed in which treatment combination maximized performance. Nitrogen concentration was greatest in high and moderately drought-stressed plants without root herbivores and moderately drought-stressed plants under low root herbivore density, and correlated positively with aphid fecundity for both species. Glucosinolate concentrations increased 62 % under combined drought stress and root herbivory, and were positively correlated with extended aphid development time. Root herbivory did not influence relative water content and foliar biomass under normal water regimes but they decreased 24 and 63 %, respectively, under high drought stress. This study shows that drought can alter the strength of interactions between foliar and root herbivores, and that plant chemistry is key in mediating such interactions. The two aphid species responded in a broadly similar way to root herbivore and drought-stress treatments, which suggests that generalized predictions of the effects of abiotic factors on interactions between above- and below-ground species may be possible.     

Hydrogel substrate amendment alleviates drought effects on young citrus plants

Water deficits affect citrus physiology, yield, fruit size and quality. Citrus can respond to drought stress conditions through endogenous hormonal regulation of water status and leaf abscission. In this work, we assayed the efficiency of an amendment to soilless media in delaying the drought stress effect in young citrus seedlings and trees. Substrate amendment promoted plant survival of citrus seedlings subjected to several cycles of drought stress and rehydration. In budded trees, the amendment increased substrate water content, leaf water potential, leaf number, root biomass, CO₂ assimilation and stomatal conductance over that of control plants growing in non-amended substrates. We conclude that the substrate amendment reduced the damaging effects of drought stress in citrus plants. The longer survival of seedlings in the amended treatment together with the reduction in leaf abscission and the improvement of physiological parameters, can account for a higher vigour of citrus grown under water stress conditions.     

Selection of large host plants for oviposition by a monophagous leaf beetle: nutritional quality or enemy‐free space?

Abstract.  1. Oviposition site selection is crucial for the reproductive success of herbivorous insects. According to the preference–performance hypothesis, females should oviposit on host plants that enhance the performance of their offspring. More specifically, the plant vigour hypothesis predicts that females should prefer large and vigorously growing host plants for oviposition and that larvae should perform best on these plants.
2. The present study examined whether females of the monophagous leaf beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae) prefer to oviposit on large host plant individuals of the meadow clary and whether large host plants are of higher nutritional quality than small host plants. Subsequently, it was tested whether the female preference correlates with offspring performance and survival.
3. In the field, females preferred large host plant individuals for oviposition and host plant quality, i.e. leaf nitrogen content, was significantly higher in leaves of large than of small host plants.
4. In the laboratory, larval development time was shorter on leaves of large host plant individuals than on small host plant individuals, but this could not be shown in the field.
5. However, a predator-exclusion experiment in the field resulted in a higher survival of larvae on large host plants than on small host plants when all predators had free access to the plants. On caged host plants there was no difference in survival of larvae between plant size categories.
6. It is concluded that females of C. canaliculata select oviposition sites that enhance both performance and survival of their offspring, which meets the predictions of the plant vigour hypothesis.     

Nutrient stress: an explanation for plant anti-herbivore responses to defoliation

Summary A hypothesis is put forward that the long-lasting inducible responses of trees to herbivores, particularly lepidopteran defoliators, may not be active defensive responses, but a by-product of mechanisms which rearrange the plant carbon/nutrient balance in response to nutrient stress caused by defoliation. When defoliation removes the foliage nutrients of trees growing in nutrient-poor soils, it increases nutrient stress wich in turn results in a high production of carbon-based allelochemicals. The excess of carbon that cannot be diverted to growth due to nutrient stress is diverted to the production of plant secondary metabolites. The level of carbon-based secondary substances decays gradually depending on the rate at which nutrient stress is relaxed after defoliation. In nutrient-poor soils and in plant species with slow compensatory nutrient uptake rates the responses induced by defoliation can have relaxation times of several years. The changes in leaf nitrogen and phenolic content of mountain birch support this nutrient stress hypothesis. Defoliation reduces leaf nitrogen content while phenolic content increases. These responses of mountain birch to defoliation are relaxed within 3–4 years.     

Induced defences in the neotropical tree Bauhinia brevipes (Vog.) to herbivory: effects of damage-induced changes on leaf quality and insect attack

Induced defences to herbivory are physical, nutritional, and allelochemical traits that change in plants following damage or stress, and that reduce the performance and/or preference of herbivores. The aim of this study was to verify the occurrence and effect of induced responses in Bauhinia brevipes (Vog.) (Leguminosae) which defend it against herbivores, through the manipulation of its leaves, and their effects on herbivore foraging behaviour. We selected 15 plants in the field, and three shoots per plant were subjected to one of three treatments: (1) damaged shoots (simulation of the main types of foliar herbivory and insect exclusion); (2) damaged control shoots (insect exclusion); and (3) control shoots (not manipulated). Water and nitrogen content, tannin concentration, levels of herbivory, and shoot growth rates were compared among treatments. Leaf quality varied among treatments. Damaged leaves showed higher tannin concentration, and lower water and nitrogen content compared to undamaged leaves. On the other hand, they experienced higher rates of herbivory than leaves on control shoots. Moreover, shoots that were experimentally induced showed a higher increase in final shoot length. These results suggest that simulated herbivory on B. brevipes reduced the nutritional quality of its leaves and increased the amount of secondary compounds, therefore altering insect herbivore attack and increasing shoot performance.     

Combined effects of drought stress and psyllid herbivory on the invasive weed Scotch broom,Cytisus scoparius

Increases in the frequency and duration of droughts under global climate change could have implications for plant–insect interactions, and could either increase or decrease the effects of weed biological control agents. In this study, we used greenhouse and field experiments to examine the impacts of drought stress on the abundance and impacts of the adventive psyllid Arytainilla spartiophila Forster (Hemiptera: Psyllidae, Arytaininae) on its target weed Scotch broom, Cytisus scoparius (L.) Link (Fabaceae), in California, USA. The psyllid impacted plant growth in both field and greenhouse experiments, whereas drought stress affected plant growth in the greenhouse only, suggesting that other factors besides water availability may be more limiting for plants in the field. Effects on psyllid survival were consistent with the plant vigor hypothesis, which predicts that herbivores will perform better on vigorously growing plants; psyllid numbers were lower on drought-stressed plants in the greenhouse and were correlated with plant growth in both the greenhouse and the field. In the greenhouse, the combined effects of the psyllid and drought stress were additive, indicating that the effects of the psyllid were consistent across unstressed and drought-stressed plants. Although the psyllid is unlikely to control Scotch broom on its own, results suggest that it may work in conjunction with drought stress to suppress Scotch broom.     

Plant stress and larval performance of a dipterous gall former

According to the plant vigour hypothesis, galling insects should respond positively and perform better on vigorous plants or plant parts, the opposite of the predictions of the plant stress hypothesis. I carried out field experiments to analyse the effects of sustained abiotic stress on the interactions between the common reed (Phragmites australis) and a gall-forming fly (Lipara lucens). The reed shoot diameter (a measure of plant vigour) is strongly affected by environmental conditions, where dry and/or nutrient-poor habitats produce thinner (stressed) shoots. L. lucens gall density is negatively correlated with shoot diameter. In a survival experiment with a wide range of shoot diameters, larval mortality was also highly correlated with shoot quality. Gall formation was higher on thinner, stressed shoots. An analysis of the gall tissues revealed that galls induced by L. lucens contain a high amount of a nutrient-rich feeding tissue. The impact of L. lucens is higher on thinner shoots. The results of this study showed that L. lucens performs better on stressed hosts, which contradicts the plant vigour hypothesis for galling insects. The low nutrient availability in the stressed shoots can be compensated by the production of galls with a nutrient-rich feeding tissue.     

Drought-induced acclimatization of a fast-growing plant decreases insect performance in leaf-chewing and sap-sucking guilds

An initial destabilization of functions triggered by drought stress in plants is followed by acclimatization and acquisition of tolerance; however, knowledge remains limited on drought-mediated changes in plant quality for herbivores. We tested whether a water-stressed fast-growing plant negatively affects host-specialist insects in both sap-sucking and leaf-chewing feeding guilds. Collards (Brassica oleracea var. acephala) were grown in well-watered, slightly water-stressed and severely water-stressed conditions. Decreasing soil moisture adversely affected plant development, assessed as a reduction in leaf number and size, stomatal size and relative water content. Severely stressed plants had less fiber and glucosinolates; however, they showed more total nitrogen and lipids. Larval survival, pupal weight, reproductive rate (Ro) and rate of population growth (r) were lower when the leaf-chewing Plutella xylostella was reared with severely stressed collards. In multiple-choice tests, moths laid fewer eggs on leaf discs of collard that were exposed to drought. The fecundity of the sap-sucking Brevicoryne brassicae was higher and the development of alates was lower when insects were fed on plants kept in well-watered regime as compared to slight-stress and severe-stress. Despite higher nitrogen content and fewer glucosinolates, a higher level of leaf surface wax in severely stressed collards possibly decreased food quality for both herbivores. Thus, host-specific herbivores of different guilds showed similar responses to drought-stressed, fast-growing plants. Water-stressed crops could discourage the attack of specialist insects, but the intensity of the stress that is required to achieve this effect will greatly reduce crop production, in terms of plant growth or foliage increment.     

Seed biopriming with drought tolerant isolates of Trichoderma harzianum promote growth and drought tolerance in Triticum aestivum

Green house study was aimed to investigate the effect of seed biopriming with drought tolerant isolates of Trichoderma harzianum, viz. Th 56, 69, 75, 82 and 89 on growth of wheat under drought stress and to explore the mechanism underlying plant water stress resilience in response to Trichoderma inoculation. Measurements of relative water content, osmotic potential, osmotic adjustment, leaf gas exchange, chlorophyll fluorescence and membrane stability index were performed. In addition, analysis of the phenolics, proline, lipid peroxidation and measurements of phenylalanine ammonia‐lyase activity were carried out. Seed biopriming enhanced drought tolerance of wheat as drought induced changes like stomatal conductance, net photosynthesis and chlorophyll fluorescence were delayed. Drought stress from 4 to 13 days of withholding water induced an increase in the concentration of stress induced metabolites in leaves, while Trichoderma colonisation caused decrease in proline, malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), and an increase in total phenolics. A common factor that negatively affects plants under drought stress conditions is accumulation of toxic reactive oxygen species (ROS), and we tested the hypothesis that seed biopriming reduced damages resulting from accumulation of ROS in stressed plants. The enhanced redox state of colonised plants could be explained by higher l ‐phenylalanine ammonia‐lyase (PAL) activity in leaves after 13 days of drought stress in Trichoderma treated plants. Similar activity was induced in untreated plants in response to drought stress but to a lower extent in comparison to treated plants. Our results support the hypothesis that seed biopriming in wheat with drought tolerant T. harzianum strains increased root vigour besides performing the process of osmoregulation. It ameliorates drought stress by inducing physiological protection in plants against oxidative damage, due to enhanced capacity to scavenge ROS and increased level of PAL, a mechanism that is expected to augment tolerance to abiotic stresses.     

Seed vigour contributes to yield improvement in dry direct‐seeded rainfed lowland rice

Dry direct‐seeded rice (DSR) cultivation is widely spreading in tropical Asia, but drought and nutrient deficiency stresses often cause crop failure in rainfed lowlands. The objective of this study was to dissect the physio‐morphological characteristics associated with crop establishment and early vigour of DSR under drought and P deficiency conditions in the Philippines. It was found that new drought‐resistant cultivars bred for DSR (Rc348 and Rc192) had faster germination and sprout growth than popular irrigated rice cultivars (Rc222 and Rc10) under soil water deficit due to rapid moisture acquisition by the germinating seeds from drying soils. There was a significant correlation between seed moisture content and the reduction in seed dry weight, and between reduction in seed dry weight and shoot elongation under both control and drought stress treatments at the germination stage. At the seedling stage, the root growth of Rc348 under drought tended to be more vigorous with its higher root‐to‐shoot ratio compared to Rc222 and Rc10. The seedling vigour of Rc348 under P deficiency was also greater than that of Rc222 due to its greater root growth and P uptake. The yields of Rc348 and Rc192 grown under rainfed condition at the target drought‐prone site where a dry spell of 13 days occurred during crop establishment were higher (4.0–4.1 t ha^?1) than the yield of Rc10 (3.0 t ha^?1). These results suggest that quick germination and seedling vigour with quick root anchorage and great nutrient uptake capacity, even with limitations of soil moisture and nutrients, would be important traits for DSR in rainfed lowlands.