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Growth, Critical N Concentration and Crop N Demand in Butterhead and Crisphead Lettuce Grown under Mediterranean Conditions
Full text linkAbstract: Excessive nitrogen (N) fertilizers are applied in lettuce causing both environmental issues
and N crop luxury consumption. In order to improve the N use efficiency (NUE) by defining optimal
crop growth and N requirements of butterhead and crisphead lettuce, two field experiments were
conducted using 0, 50, and 100 kg ha−1 of N fertilizer to study (i) the growth and productivity, (ii)
the NUE, (iii) the critical N dilution curve, and (iv) the N demand. Nitrogen supply enhanced dry
weight (DW) accumulation in the butterhead (from 295 to 410 g m−2), but not in the crisphead type
(251 g m−2). The NUE indices underlined the poor ability of the crisphead type in absorbing soil N
and also in the utilization of the absorbed N for producing DW. The critical N dilution curves %Nc
= 3.96 DW^−0.205 and %Nc = 3.65 DW^−0.115 were determined for crisphead and butterhead lettuce,
respectively. Based on these type-specific %Nc curves, the estimated N demand was 125 kg ha−1 in
the butterhead and 80 kg ha−1 in the crisphead lettuce for producing 4.3 and 2.5 Mg ha−1 of DW,
respectively, under Mediterranean climate. Neither N fertilization nor genotype affected crop
productivity
Caratterizzazione di capolini di carciofo cv. Madrigal per la trasformazione industriale
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Effect of seed age, stratification, and soaking on germination of wild asparagus (Asparagus acutifolius L.)
No full textWild asparagus (Asparagus acutifolius L.) is a widespread species found in all the Mediterranean areas. The
spears are highly valued by consumers and owing to its frugality, this species is a feasible new crop with
high income potential, especially for Mediterranean marginal areas. Currently, the cultivation of this
species is limited because of its low and erratic seed germination that makes difficult the production of
seedlings for plant propagation. In this research, non-after-ripened (1 month-old) and after-ripened
seeds (dry stored at room temperature for 13 months) were exposed for 30 days in the dark to three moist
stratification treatments: cold (5 8C), warm (23 8C) or no stratification; subsequently they were soaked
for 12 h in warm water (35 8C) or not soaked. The effect of these pre-germination treatments on three
germination parameters (germination percentage, time to 50% of final germination – T50 – and
germination pattern) was studied, as well as some possible seed dormancy forms involved therein. The 1-
year dry storage period proved to be effective in after-ripened seeds by enhancing seed sensitivity to the
subsequent pre-germination treatments. After-ripened seeds exhibited higher and more rapid
germination compared to non-after-ripened seeds. Soaking, cold or warm moist stratification had
similar single effect on non-after-ripened seeds (27% germination). With after-ripened seeds, only
soaking or warm stratification were effective (47% germination) when singularly applied, while cold
stratification did not improve germination. By combining stratification and soaking treatments, a higher
germination for both non-after-ripened and after-ripened seed-lots was achieved. The highest
germination was obtained when after-ripened seeds were stratified and soaked (76%), without any
significant difference between cold or warm stratification. Single or combined application of moist
stratification (regardless of the temperature used) and soaking resulted always in a faster germination
compared to that of no-treated seeds and especially with after-ripened seeds (T50 = 6 days). A non-deep
type 1 physiological dormancy can be hypothesized for the seeds of this species. Low stratification
temperature induce secondary dormancy in after-ripened seeds that can be removed by soaking them at
35 8C for 12 h
Mineral nutrition aspects in artichoke growing
No full textThis paper reviews NPK and minor elements nutrition for artichoke crop. Artichoke is characterized by a long crop cycle lasting from 7 to 10 months. Its dry mass (DM) production is highly influenced by the environment, being in the Mediterranean two times higher in the southermost region of Italy and Spain compared to the south of France, and by the cultivar, ranging from about 11-12 t-ha(-1) for the traditionally propagated cultivars to more than 31 t-ha(-1) for the 'seed'propagated ones. The uptake pattern of mineral elements follows that of DM accumulation and therefore it is influenced by climate, cultivar, type of soil, and crop management. Data from literature reports uptake ranging (in kg-ha-1) from 112 to 279 for N, from 340 to 450 for K2O, from 35 to 125 for P2O5, from 150 to 300 for Ca, from 24 to 40 for Mg. Artichoke has also the capacity to accumulate large quantity of Na in the older leaves of plant, while for NPK the leaf concentration decreases markedly with the age of the plant. Fertilization plays a basic role on artichoke productivity, however, literature data concerning the effect of NPK fertilization on yield and quality of artichoke shows variability depending on soil fertility, cultivar, cultural practices and climatic conditions. The application of around 200 kg-ha-1 N is normally suggested for improving yield, while N fertilization has been reported to be inversely correlated with caffeoylquinic acids and flavonoids content in plant tissue. Phosphorus and K fertilization have been related to the improvement of earliness, but a balanced NPK fertilization has often been indicated as main factor influencing yield and earliness. Lack in soil P availability or a high K/P ratio has been related to the occurrence of "black tip" disorder. High soil salinity or high temperatures conditions are responsible for symptoms (brown discoloration of inner bracts and head atrophy) that could be related to impaired Ca transport in the low-transpiring inflorescences
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