 Premise of the study: Few previous studies have considered how plant age affects photosynthetic physiology in herbaceous perennials or how photosynthetic capacity in annual cereals compares to perennial relatives. Newly developed perennial cereals offer novel systems for addressing these questions. Our study makes a novel contribution by considering how life history differences affect photosynthetic physiology.  Methods: In two linked fi eld studies, we evaluated effects of life history and plant age on photosynthetic rates ( A ), and related biochemical, morphological, and water-relations traits, comparing 1- and 2-yr-old cohorts of perennial wheat, intermediate wheatgrass, and perennial rye to close annual relatives (wheat and rye).  Key results: Photosynthetic rates ( A ) were 10–50% higher in perennial cereals compared to annuals. In wheatgrass, elevated A was associated with higher carboxylation ( V C ), triose phosphate utilization (TPU) and electron transport rates ( J ), and higher leaf soluble protein and chlorophyll. Younger wheatgrass plants maintained higher A , TPU , J , and V C than older plants did. Perennial wheat and rye differed from annual relatives in some but not all of these parameters. Differences in stomatal limitation were not involved, while differences in stomatal conductance ( g s ) became evident under drier conditions.  Conclusions: This study demonstrates that some perennial cereal species can maintain higher midseason A than their annual crop relatives. These changes are not fully explainable by increased access to soil water and may refl ect trade-offs between allocation to reproduction and to resource acquisition. We also found evidence for age-related changes in photosynthetic physiology in a herbaceous perennial plant.

Life history and resource acquisition: Photosynthetic traits in selected accessions of three perennial cereal species compared with annual wheat and rye

Dendrocalamus minor var. amoenus was analyzed for physiological and proteomic responses under drought stress. The adverse effects of drought on D. minor var. amoenus were primarily affected by gas exchange attributes such as photosynthesis (Pn), stomatal conductance (Gs), and transpiration rate (Tr) decreased as drought intensity increased. Among chlorophyll fluorescence parameters, actual photochemical efficiency of PSII (ΦPSII), electron transport rate (ETR), and non-photochemical quenching (qN) also decreased under increasing drought stress throughout the natural dehydration process (15-30 days). Moreover, superoxide dismutase (SOD) and catalase (CAT) levels increased significantly when subjected to short drought event and then decreased rapidly under severe drought stress. Using twodimensional gel electrophoresis (2-DE), we detected more than 500 protein spots; 41 significant differentially expressed protein spots were uncovered under drought stress. Following matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) identification and BLAST of these 41 proteins spots to an NCBI or Uniprot database, 33 differential protein spots were identified. In addition to determining a suitable protocol for protein extraction from D. minor var. amoenus (or other bamboo species), this study provides important information on signal transduction pathway changes under drought stress for exploring drought resistance candidate genes in bamboo species.

Physiological and proteomic responses of dendrocalamus minor var. amoenus (ghost bamboo) under drought stress

Perennial crops are emerging as an effective strategy for adapting to climate change, but also for mitigating net greenhouse gas emissions from agriculture. This study aims to investigate the agronomic and physiological performance of selected perennial wheat genotypes derived from crosses between Triticum aestivum L. and Thinopyrum spp to evaluate if they could give a contribute both to face climate changes and to restore soil health. Four perennial wheat genotypes were grown in Central Italy and compared in terms of agronomic traits, root development (biomass and length) and ecophysiological parameters with an annual common wheat cultivar. Plants were, on average, taller in perennial wheat genotypes than in annual wheat as well as the number of tillers per plant (+ 49%), root length (+ 43%) and root biomass (+ 31%) in both years, whereas, perennial wheat kernels were smaller (− 15%). Post harvest regrowth occurred in different amounts in all perennial wheat genotypes. In terms of the ecophysiological response, perennial wheat lines revealed higher soil respiration and lower stomatal conductance than annual wheat. On the contrary, transpiration rate, water use efficiency and photosynthesis were higher in annual genotype than in perennial ones. The environmental benefits of adopting perennial grains are discussed together with suggestions on optimal field management and future breeding strategies.

Agronomic and ecophysiological evaluation of an early establishment of perennial wheat lines in Central Italy

This study compared the leaf blade characteristics, pigment composition, photosystem II (PSII) photochemistry, and photosynthetic rates (P) of a multi-stemmed annual (Zea mays ssp. parviglumis Iltis & Doebley) and a perennial (Z. diploperennis Iltis, Doebley & Guzman) teosinte species growing in a glasshouse under analogous nutritional and environmental conditions. Similar chlorophyll contents and ratios implied comparable efficiencies of photon energy capture and electron flow through PSII in both species. Maximum photochemical efficiency (Fv/Fm) was about 0.75 at predawn and declined linearly to a minimum at midday of about 0.65, implying down-regulation of photosynthesis. By contrast, maximum P (Pmax) was 11.5% higher in the annual compared to the perennial teosinte, signifying that wild maize germplasm could potentially be used for improving the photosynthetic efficiency of cultivated maize. Future studies, however, should assess a larger number of teosinte species for their differences in leaf area per plant, growth habit, grain yield, and leaf photosynthesis.

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M. A. Sobrado

Papers

Leaf gas exchange and fluorescence of two teosinte species: Zea mays ssp. parviglumis and Z. diploperennis.