Search

A 2-yr field study was conducted to evaluate the effects of calcium cyanamide as an alternative nitrogen (N) fertilizer source on N use efficiency (NUE), yield, and quality of two types of lettuce (Lactuca sativa L.), romaine (var. longifolia, cv. Manavert) and red oak-leaf (var. crispa, cv. Aruba), grown on clay soil under a Mediterranean environment. Pretransplanting application of 120 kg ha-1 of N as calcium cyanamide (120CC) was compared with a traditional split application of 120 kg ha-1 of soluble N (120SN) consisting of 50% ammonium sulfate applied before transplanting and 50% as ammonium nitrate applied after transplanting. An unfertilized control (0-N) was included to calculate NUE indices. At harvest leaf area index, dry weight, fresh yield, dry matter concentration, and NUE indices were not affected by the N source. Leaf nitrate (NO3-) content was on average 55 and 41% higher in Aruba than in Manavert in the first (Exp-1) and second (Exp-2) season, respectively. Plants fertilized with 120CC had lower leaf NO3- content (41 and 18% in Aruba and 70 and 21% in Manavert in Exp-1 and Exp-2, respectively) compared with those fertilized with 120SN. These results suggest calcium cyanamide may be used as an effective tool to reduce leaf NO3- accumulation and to produce high-quality lettuce in compliance with European Regulation No. 1258/2011 while assuring competitive yields.

Protecting the environment by improving the crop-system nitrogen (N) use efficiency (NUE) while maximising yield and quality is a primary challenge for modern agriculture, and understanding the processes that govern N fluxes in the plant-soil system is essential to improve NUE. An on-farm study was conducted over two fall-winter seasons to evaluate the NUE, agronomical and physiological response of romaine (var. longifolia , cv Manavert) and red oak-leaf (var. crispa , cv Aruba) lettuce ( Lactuca sativa L.) to different N-rates (0, 60, 120, 180 kg ha–1 of N). Nitrogen rate influenced all tested parameters, including plant fresh and dry weight, N accumulation, leaf NO 3 – and dry matter content, NUE indices, N nutrition index (NNI), soil residual N and the estimated N losses at the end of the crop season. Fresh yield, dry weight and N-accumulation response to N rate were influenced by lettuce genotype. Manavert had higher N recovery, NUE, and lower leaf NO 3 – concentration than Aruba. Analysing the NNI overtime, 120 kg ha –1 of N assured an optimal N status in both Manavert and Aruba, while N deficiency and excess were observed at lower and higher N-rates, respectively. An empirical relationship was observed between NNI and leaf NO 3 – concentration, suggesting that leaf NO 3 – concentration may be used to predict NNI and thus the crop N status. The relationship between NNI and leaf NO 3 – concentration may be used to define optimal leaf NO 3 – concentration ranges for the rapid and site-specific assessment of the crop N status, and the dynamic adjustment of N-fertilisation, contributing to improve crop NUE, minimise N-losses, and optimise yield and quality of lettuce crops.

“Early” potato is a typical crop grown in most of the Mediterranean countries, and it is one of the most important horticultural crops exported towards the Northern European markets. In order to improve market value of early potatoes, growers are more and more involved in choosing new potato varieties and constantly looking for methods to improve the commercial quality of tubers. One of the most increasingly used agro-techniques is chemical haulm desiccation, which aims to simplify harvesting and can help to manipulate tuber size distribution and tuber skin-set. Its effect on yield and quality aspects of early potato remains to be better evaluated. This paper resumes results of trials and analysis conducted during 2007 concerning the effect of the application of a chemical desiccant (gluphosinate ammonium) on some relevant nutritional parameters of three early potato varieties (Spunta, Ditta, and Krone) grown in Southern Italy. Tubers from the trials were analyzed for tuber size distribution, flesh and skin colour, dry matter, nitrate, soluble carbohydrates, total and resistant starch, vitamin C, phenol content, and total antioxidant activity. Results indicate that chemical desiccation does not affect the levels of vitamin C and those of other molecules with antioxidant properties as well as those of total soluble carbohydrates. On the other hand, it induces a significant decrease in starch storage and an increase in the percentage of resistant starch (a component of dietary fibre).

BACKGROUND: Glufosinate-ammonium (GA) is used for chemical vine killing of potato crop before harvest. Over two years we tested the effect of GA, applied at 0.48 kg ha−1 of active ingredient, on desiccation of haulms, yield and some qualitative traits of tubers of three cultivars of early potatoes, a typical crop of southern Italy and large areas of the Mediterranean countries. RESULTS: Seven days after treatment desiccation reached 90% of leaves for all cultivars. At harvest, the highest desiccation percentage of haulms was 85% in Spunta. The desiccant did not affect yield in either year during which the analysis was carried out, but it increased the percentage of tubers in the range of 35–70 mm in diameter. In the first year, the treatment decreased dry matter and vitamin C content and increased free sugar concentration in tubers. In the second year, no negative effects on the nutritional traits were observed. Strong differences were found on yield and quality between the two years as a result of the different climatic conditions. CONCLUSION: In the two experiments GA had no influence on yield, but increased the percentage of potato tubers in the 35–70 mm range. From a qualitative standpoint in 2004 the chemical vine-killing treatment had some negative effects (decreased dry matter and vitamin C content, increased free sugar concentrations), whereas no such negative effects were observed in 2005. Copyright © 2009 Society of Chemical Industry