Wood ash as a soil amendment has gained wide spread acceptance in the recent years as a sustainable alternative to chemical fertilizers, although information regarding the effects of its application on maize growth and yield in the context of climate change and increasing drought severity is lacking till date. In the present study, field and pot trials were carried out at the experimental farm of the University of Padova at Legnaro (NE Italy) in a silty-loam soil in order to investigate the effects of soil amendment with wood ash (0.1% w/w, incorporated into the 0.2-m top soil) on the bioavailability of mineral elements and their uptake by maize. Characteristics analyzed included plant growth, leaf transpiration dynamics, and productivity in two contrasting hybrids, P1921 (drought sensitive) and D24 (drought tolerant). Wood ash contained relevant amounts of Ca, K, Mg, P, and S, and hazardous levels of Zn (732 mg kg−1), Pb (527 mg kg−1), and Cu (129 mg kg−1), although no significant changes in total soil element concentration, pH, and electrical conductivity were detected in open field. Ash application led to a general increasing trend of diethylene triamine penta-acetic acid (DTPA)-extractable of various elements, bringing to higher grain P in D24 hybrid, and Zn and Ni reductions in P1921 hybrid. Here, the results demonstrated that ash amendment enhanced shoot growth and the number of leaves, causing a reduction of harvest index, without affecting grain yield in both hybrids. The most relevant result was a retarded inhibition of leaf transpiration under artificial progressive water stress, particularly in the drought-tolerant D24 hybrid that could be sustained by root growth improvements in the field across the whole 0–1.5 m soil profile in D24, and in the amended top soil in P1921. It is concluded that woody ash can be profitably exploited in maize fertilization for enhancing shoot and root growth and drought tolerance, thanks to morphological and physiological improvements, although major benefits are expected to be achieved in drought tolerant hybrids. Attention should be payed when using ash derived by metal contaminated wood stocks to avoid any health risk in food uses.

The objective of this work was to perform a comparative analysis of the physiological, biochemical and agronomical parameters of recent and heritage durum wheat cultivars (Triticum durum Desf.) under water-deficit conditions. Five cultivars were grown under irrigated (control) and rainfall (stressed) conditions. Different agro-physiological and biochemical parameters were studied: electrolyte leakage, relative water content, chlorophyll fluorescence, proline, soluble sugars, specific peroxidase activity, yield and drought stress indices. It was revealed that a water deficit increased proline content, electrolyte leakage, soluble sugars and specific peroxidase activity and decreased relative water content, fluorescence and grain yield. According to these parameters and drought stress indices, our investigation indicated that old cultivars are the best-adapted to local conditions and showed characteristics of drought tolerance, while recent cultivars showed more drought susceptibility. Therefore, local cultivars of each country should be kept by farmers and plant breeders to preserve their genetic heritage.

Root characteristics and metal uptake in the maize hybrid Naudi were studied in a pot trial, using soil artificially highly polluted with Zn, Cu, Co, Cd, and Pb. The addition of these metals as sulfates decreased the soil pH and increased electrical conductivity. As a result of increased bioavailability in the soil pore water, significantly higher concentrations of metals, particularly Pb, Cu, and Co, were found in the shoot tissues of maize at the 3–4 leaf stage. While the lowest increase was in Cd (0.89 mg kg−1 vs. 0.33 mg kg−1 for controls), Zn reached a critical threshold of 75 mg kg−1 vs. 2.76 mg kg−1. Fresh and dry weights of shoots and roots, as well as root length, were markedly reduced, whereas root diameter, tip density, and the branching index increased considerably. A significant adaptation strategy by maize in the polluted soil was an increased fraction of coarse root length and a decreased fraction of finer roots. We conclude that maize is very sensitive to multiple metal pollution, suggesting its potential use as a test plant to evaluate contaminated soils. As length was the most affected root characteristic, measurement of this parameter could be a way of screening genotypes for tolerance to metal contamination and possibly salinity. There also is future scope for investigating whether K fertilization might mitigate metal phytotoxicity, in view of the negative correlations between the shoot K concentration and concentrations of the supplied metals.

Table SI1. Initial chemical proprieties and concentrations of total, DTPA-extractable and water-extractable elements (mg kg -1 DW) in biochar (mean ± S.E.; n = 3).

No abstract

Les modifications des caractéristiques hydriques -potentiel hydrique foliaire (ψ F ) et teneur relative en eau (TRE) -d'une plante rendent compte de son statut hydrique et aussi de sa capacité à incorporer l'eau, particulièrement en situation de contrainte hydrique. Ces caractéristiques ont été utilisées pour différencier le comportement de six écotypes autochtones de mil (Pennisetum glaucum (L.) R. Br.) soumis à différents régimes hydriques. Les résultats ont montré que le ψ F et la TRE évoluent dans le même sens et diminuent en présence de stress hydrique. Ces caractéristiques hydriques sont également très importantes, puisqu'elles conditionnent le rendement. L'étude a montré également que les six écotypes de mil présentent deux comportements types : le premier groupe est caractérisé par une chute importante du ψ F et de la TRE, traduisant un ajustement osmotique de type adaptatif, tandis le second a montré une faible réduction du potentiel hydrique foliaire, tout en maintenant une TRE sensiblement plus élevée, ce qui pourrait être le résultat d'une réduction importante du potentiel osmotique due à une accumulation active de solutés (ajustement osmotique constitutif). De plus, la variabilité génétique du matériel végétal vis-à-vis du stress hydrique ne semble pas liée à l'origine géographique des écotypes de mil, mais plutôt à leur phénologie et à leur morphologie.

Cette étude a pour objectif de comparer le comportement de six écotypes de mil autochtones collectés à travers le territoire tunisien et soumis à des conditions de stress salin, depuis le stade germination jusqu'à la maturité complète. Elle a montré que le sel exerce un effet peu marqué sur le taux de germination et sur l'émergence du coléoptile. En revanche, cet effet est plus significatif pour la croissance radiculaire, avec des différences entre écotypes. La salinité n'a pas influencé la hauteur des plantes, qui semble être une caractéristique variétale, mais a favorisé l'expansion foliaire. Sur le plan productif, la salinité n'a pas eu d'effet préjudiciable sur la longueur de la chandelle principale, mais a amélioré la composante rendement de cette dernière. Cependant, cet effet varie en intensité selon la charge en sel et l'écotype en question. Ainsi, les écotypes à haute paille sont les seuls à avoir subi une réduction de leur hauteur et une diminution du rendement en grains de leur chandelle principale face à la salinité sévère. En revanche, les écotypes dont la hauteur est moyenne ou faible paraissent très stables sur le plan productif. De tels écotypes peuvent jouer un rôle dans la conservation et la mise en valeur des sols fragiles et aussi servir comme source de gènes désirables pour l'amélioration génétique dans des conditions de salinité.

The objective of this study was to identify morphological and physiological traits for salinity tolerance in Tunisian autochthonous ZZ pearl millet ecotype (Pennisetum glaucum (L.) R. Br) under local conditions. ZZ ecotype was cultivated under different levels of salinity and growth parameters, water relations and mineral content were measured. Results showed that ZZ pearl millet ecotype was unable to store the large amounts of salt in the leaves, while maintaining high leaf water content and without a grave consequent on panicle yield. This ecotype is fitted for a selective sodium sequestration in the vacuole.