J.V. Maroto

Effects of grafting and cytokinin-induced fruit setting on colour and sugar-content traits in glasshouse-grown triploid watermelon.

Summary The effect on fruit quality of grafting and fruit set treatments, was determined in the triploid watermelon (Citrullus lanatus (Thun.) Matsum. and Nakai) cultivar ‘Reina de Corazones’ grown in a heated greenhouse. Grafting the scion onto ‘Shintoza’ (Cucurbita maxima × Cucurbita moschata) rootstock and setting fruit through application of the synthetic cytokinin CPPU [1-(2-chloro-4-pyridyl)-3-phenylurea] retarded the accumulation of sugar and development of the flesh colour of the fruit, compared to fruit from non-grafted, pollinated plants. The effects of grafting and of CPPU application on sugar accumulation were additive. At commercial maturity, the fruit of grafted and/or CPPU-treated plants had lower total soluble solids and sugar concentrations, and lower sucrose to hexose ratios, than fruit from control plants. Fruit from CPPU-treated plants also had a weaker red colour than fruit set by pollination. Despite this loss of quality, fruit from grafted plants, set with CPPU and grown in a heated greenhouse, had a total soluble solids concentration similar to fruit from pollinated, non-grafted plants, grown outdoors.

Growth and nutrient absorption in chufa (Cyperus esculentus L. var. sativus Boeck.) in soilless culture

Summary The efficiency of fertilisation in agriculture is often low and, provided one knows the nutrient uptake rate, the efficiency can be improved by synchronising nutrient supply with nutrient demand. Growth, the time-course of nutrient accumulation and its partitioning between different organs in chufa (Cyperus esculentus L. var. sativus Boeck.), an under-exploited cultivated plant, were examined. The study was conducted in soilless, open-field conditions, at a planting density equivalent to 55,500 plants ha−1 in three consecutive seasons. Plants were sampled, fractionated into leaves, roots, and tubers, then dried and weighed. Their macronutrient contents were analysed each fortnight. On average, the yield was 5.0 kg fresh weight of tuber m−2. Growth of whole plants, until 90 d after planting, obeyed an exponential function of time. The relative growth rate (RGR) for this period was therefore determined. The highest N and K concentrations were recorded in leaves, and the highest P, Ca, and Mg concentrations were found in roots. The highest accumulations of N and P were found in tubers, and of K and Ca in leaves. Nitrogen had the highest nutrient accumulation (58.3 g m−2) as well as the highest specific uptake rate.

Saving Water in Chufa Cultivation by Using Flat Raised Beds and Drip Irrigation

AbstractChufa, also known as tigernut, is a typical crop in Valencia, Spain, where it is cultivated in ridges with furrow irrigation. This paper examines the effects of the planting strategy (PS) and irrigation system (IS) on yield and irrigation water use efficiency (IWUE) on the basis of the results from a two-year study. The authors analyzed three PS, ridges with a plant row (R) and flat raised beds containing two (B2) or three (B3) plant rows and compared two IS, furrow (FI) and drip irrigation (DI). Irrigation was based on the volumetric soil water content (VSWC), continuously monitored with capacitance sensors. Each irrigation event started when the VSWC in R dropped to 60 or 80% of the field capacity in FI or DI, respectively. Beds and ridges were irrigated simultaneously and for the same duration. There were differences among IS and PS, with DI and B2 obtaining the highest yield. On average, DI produced higher IWUE values than FI; the highest IWUE was obtained in R for DI, and the lowest IWUE was ...

Influence of cation proportions of the nutrient solution on tipburn incidence in strawberry plants.

ABSTRACT To determine their influence on leaf tipburn incidence and yields six nutrient solutions with different proportions of potassium (K), calcium (Ca), and magnesium (Mg) were tested in ‘Camarosa’ strawberry plants. Response models were made to predict tipburn incidence, yields and fruit weight. A high Ca proportion in the nutrient solution was determinant for high yields in the first season, while a high Mg content was fundamental for high marketable yields during the two last seasons. In 2001 and 2002, the average fruit weight was higher with high Mg levels, and in 2000 the lowest fruit weights coincided with low levels of Ca in the nutrient solution. The models for tipburn incidence in 2000 and 2002 indicated that solutions with intermediate to high levels of Mg and intermediate to low levels of Ca resulted in a more frequent incidence of tipburn. Conversely, in 2001, the highest tipburn incidence appeared with high K contents.

Analysis of germination of caper seeds as influenced by the position of fruit on the mother plant, fruit maturation stage and fruit weight

Summary This two-year study (1999-2000) analysed the effects of three factors on the germination of caper seeds: the fruit position on the mother plant, the fruit maturation stage and the unit fruit weight. Plants of cultivar Común were grown in Valencia, Spain. Ripe fruits were collected in September and early October. Mature dark brown seeds were selected. Germination tests were performed in closed Petri dishes in a growth chamber. Germination data were fitted to the logistic function and variables such as the maximum germination percentage; the time to reach 50% of final germination and the mean relative cumulative rate were calculated. The results indicate that the use of the logistic function is adequate to analyse the germination of caper seeds. The final germination percentage was affected by fruit position and unit fruit weight, but not by the fruit maturation stage. The best results, over 90%, were obtained with fruits of large or medium size and with fruits set in the central or apical region of the branches. The time to reach 50% of final percentage and the mean relative cumulative rate were not affected by the factors studied. There were marked differences between the average values of these variables corresponding to the two years studied.

Influence of watering on the yield and cracking of cherry, fresh-market and processing tomatoes.

Summary This two-year study (1994–95) analyses the effects of different irrigation treatments (using a drip irrigation system and furrow irrigation) and the subsequent varying degrees of soil water tension on both the productive response of tomato and the appearance of fruit cracking. Three cultivars were tested in these experiments: Evita 52®, a cherry tomato, Aguilas®, a fresh-market tomato and Guay®, a processing tomato. The fresh-market cultivar and that of the cherry type were grown in greenhouses using a drip irrigation system. The processing cultivar was grown under a floating cover with furrow irrigation. The irrigation treatments for both years were based on crop evapotranspiration (ETc) and their values were 0.5, 1.0 and 1.5 ETc for the first year, and 0.4, 0.8 and 1.2 ETc for the second year for the cultivars tested in greenhouses with the drip irrigation system. The cultivar grown outdoors received furrow irrigation with the values 0.5 and 1.0 ETc for the first year and 0.4 and 0.8 ETc for the second year. Soil water was measured with tensiometers during the entire treatment period. Higher rates of irrigation increased yields in two of the three cultivars. Longitudinal cracking was the type most frequently observed in these experiments. In both years of the furrow irrigation experiments, the incidence of cracking was high when large fluctuations of the soil matric potential were induced after having maintained high negative values of this parameter during several previous days. In the experiments using drip irrigation, cracking was limited, but increased when high fluctuations in the soil matric potential were induced after having maintained high negative values of matric potential for several previous days, as was the case with furrow irrigation. Differences in cultivar susceptibility to fruit cracking were detected in the experiments. More cracking occurred during periods of higher temperatures.

Enhancing root systems of waiting-bed strawberry plants grown on substrates

Summary To find techniques to improve root system development of waiting-bed strawberry plants ‘Camarosa’ grown in substrates, the influence of two substrates (peat and coconut coir dust), or plants from three waiting-beds at different altitudes, and of root treatments with different plant growth regulators (naphthalenacetic acid at 25, 50 and 75 mg g–1; indolebutyric acid at 10, 20 and 30 mg g–1; l-triacontanol at 0.02, 0.04 and 0.06 mg g–1) by dipping runners prior to planting, were studied in two experiments in the 1997–98 and 1998–99 seasons. In both years, plants from high elevation beds (HE) produced the greatest root development, and plants from medium elevation beds (ME) produced more new roots than those from low elevation beds (LE). Root development of plants grown in peat was greater than those grown in coconut coir dust in the first experiment and only on the first measuring dates (one month after planting). This difference was particularly high in plants from high or medium elevation nurseries, when the degree of root development was greater. No differences between substrates were observed in the second experiment. Treatments with the different growth regulators tested, at any of the concentrations used, did not improve root development on average for the other factors.

Nutrient uptake of pepino plants in soilless cultivation

Summary This study addresses vegetative growth and the uptake of nutrients and their accumulation in the vegetative and reproductive tissues of pepino (Solanum muricatum Ait.). The study was conducted in soilless plastic house conditions, with a planting density equivalent to 25.000 plants ha–1 during two seasons (1997–98 and 1998–99). The plants were sampled, fractionated into leaves, stems, fruits and roots, then dried and weighed and the macronutrient content was analysed every 30.d for 300.d after transplanting. The yield obtained was 2.kg of fruit per plant, which is 30% of the total dry weight. The relative growth rate (RGR) ranged from 0.0028 to 0.0451.d–1. The highest N, K, Ca and Mg concentrations were recorded in the leaves, and the highest P concentration in the roots. The nutrient accumulation of this yield was 10.64, 1.12, 16.06, 10.0 and 1.58.g of N, P, K, Ca and Mg per plant respectively. The highest accumulation of all nutrients was found in the leaves. The nutrient with the highest specificuptake rate was K, which ranged from 0.0037 to 0.0838.g g–1 d–1.

Tipburn Incidence on Chinese Cabbage (Brassica campestris L. ssp pekinensis rupr.) Cultivated Under Greenhouse and its Prevention by Application of a High Calcium Foliage Fertilizer

It has been studied the incidence of Tipburn on three varieties of Chinese cabbage (Hi-Mark, Nagaoka Spring A-1 and Price) under two growing systems (greenhouse with heating and cooling system and greenhouse without any climatical regulation) and the influence of applications of a high calcium foliage fertilizer on the incidence of this disease. The obtained results have been the following: Hi-Mark was the least Tipburn susceptible variety The incidence of Tipburn was the least under greenhouse with climatical regulation It has had a clear response to foliage fertilizer, stated as a lesser of Tipburn

Effect of different levels of nitrogen in nutrient solution and crop system on nitrate accumulation in endive

ABSTRACT With the objective of studying the effect of two nutrient solutions and two crop systems (greenhouse and openfield) on nitrate accumulation, incidence of tipburn and chlorophyll content, endive (cv. Cuartana) was planted in 8 L pots, filled with a mixture of coconut coir:perlite (1:1) in three different cycles C1 (winter), C2 (spring) and C3 (summer). Plants were irrigated with two nutrient solutions of different nitrate content: S1, low ([NO−3] = 7.91 mmol L−1) and S2 moderate nitrate content ([NO−3] = 16.91 mmol L−1). Nitrate content was determined by reflectometry, tipburn was evaluated using a qualitative scale and chlorophyll content by soil plant analysis development(SPAD) values. Plants irrigated with S2 showed higher nitrate accumulation in leaves in all cycles, however, no influence of the nutrient solution was observed on the incidence of tipburn. Greenhouse-cultivated plants accumulated more nitrates than those cultivated in open field and also showed a higher incidence of tipburn and SPAD values.