ISSN e:2007-4034 / ISSN print: 2007-4034

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     Vol. 17, issue 3 September - December 2011   Creative Commons License

      
 

     Vol. 17, issue 3 September - December 2011  

 
  

In vitro CULTURE OF PITAYO (Stenocereus stellates [Pfeiffer] Riccobono)

CULTIVO in vitro DE PITAYO (Stenocereus stellates [Pfeiffer] Riccobono)

Ylvi María Martínez-Villegas; María Andrade-Rodríguez; Ángel Villegas-Monter; Irán Alia-Tejacal; Oscar Gabriel Villegas-Torres; Víctor López-Martínez

Keywords: Cactaceae, cytokinins, tissue culture, plant multiplication, pitayo.

10.5154/r.rchsh.2011.17.021

Received: 2011-03-24
Accepted: 2011-09-08
Available online:
Pages:95-105

The pitayo (Stenocereus stellatus) is a cactus native to Mexico that is prized for its fruits, which have unique organoleptic characteristics. It is propagated by cuttings taken from mature, usually wild plants, causing deforestation of natural areas. The objective of this study was to identify the optimum ctyokinin type and dose, plus sucrose concentration, to obtain a greater number of pitayo plants in vitro. Seeds from ripe fruits were used to obtain seedlings to initiate plant growth. For shoot multiplication, seedlings measuring 2 to 3 cm in height and divided into 1-cm sections were used. MS medium with 3 % sucrose was used. Three cytokinins (kinetin, 6-benzyladenine, and 2-isopen¬tenyladenine) at five concentrations (2.2, 4.4, 8.8, 17.6 and 35.2 μM) were evaluated. For shoot growth, MS medium with sucrose (1, 2, 3, 4 and 5 %) was used. In plant acclimatization, the effect of the sucrose concentration used for in vitro shoot growth was assessed. It was found that the concentration of 17.6 μM 6-benzyladenine caused shoot formation in all explants, with eight shoots per explant. The shoots achieved the greatest height when grown in 3 and 4 % sucrose. Over 92 % of the plants transplanted to substrate survived acclimatization.

The pitayo (Stenocereus stellatus) is a cactus native to Mexico that is prized for its fruits, which have unique organoleptic characteristics. It is propagated by cuttings taken from mature, usually wild plants, causing deforestation of natural areas. The objective of this study was to identify the optimum ctyokinin type and dose, plus sucrose concentration, to obtain a greater number of pitayo plants in vitro. Seeds from ripe fruits were used to obtain seedlings to initiate plant growth. For shoot multiplication, seedlings measuring 2 to 3 cm in height and divided into 1-cm sections were used. MS medium with 3 % sucrose was used. Three cytokinins (kinetin, 6-benzyladenine, and 2-isopen¬tenyladenine) at five concentrations (2.2, 4.4, 8.8, 17.6 and 35.2 μM) were evaluated. For shoot growth, MS medium with sucrose (1, 2, 3, 4 and 5 %) was used. In plant acclimatization, the effect of the sucrose concentration used for in vitro shoot growth was assessed. It was found that the concentration of 17.6 μM 6-benzyladenine caused shoot formation in all explants, with eight shoots per explant. The shoots achieved the greatest height when grown in 3 and 4 % sucrose. Over 92 % of the plants transplanted to substrate survived acclimatization.

 

INBREEDING OF SYNTHETIC VARIETIES DERIVED FROM LINES AND SINGLE CROSSES

ENDOGAMIA DE SINTÉTICOS FORMADOS CON LÍNEAS Y CRUZAS SIMPLES

Jaime Sahagún-Castellanos; Juan Enrique Rodríguez-Pérez

Keywords: Allium cepa L., Zea mays L., coancestry, prediction, genotypic array

10.5154/r.rchsh.2011.17.022

Received: 2011-02-09
Accepted: 2011-09-12
Available online:
Pages:107-115

The exploitation of heterosis in crops such as tomato (Licopersicon esculentum Mill.), onion (Allium cepa L.) and corn (Zea mays L.) has been limited by the high cost of F1 seed. To avoid this, producers have resorted to using F2, F3 ... seed. However, the inbreeding depression that this practice produces has led plant breeders to consider the synthetic varieties (SVs), particularly for cross-pollinated crops, which are not, however, without problems. In this work, the derivation of a SV whose parents are L lines and s single crosses (SynL,SC) is propo¬sed as a way of decreasing the parent number (originally L+2s lines) and thereby also the costs and work involved in prediction. However, the most important SynL,SC quality indicators must be known in order to make an objective assessment. Thus, the study objectives related to SynL,SC were to determine: 1) the inbreeding coefficient (FSynL,SC) and 2) the best combination of L and s values. The derivation of FSynL,SC was based on the replacement of the general genotype of the genotypic array of SynL,SC (GASynL,SC) by the coancestry between the individuals that contribute the genes that make up this genotype, and the best combination of L and s values was the one that produ¬ced the lowest inbreeding coefficient. From a fixed even number of L + 2s fully inbred and unrelated lines and from two decompositions of GASynL,SC, it was found that FSynL,SC={1+Ls/[2(L+s)2]}/(L+2s). By inspection of the formula, FSynL,SC reaches its minimum in two cases: when L = 0 and when s = 0. However, the use of (L+2s)/2 single crosses requires fewer resources for prediction.

The exploitation of heterosis in crops such as tomato (Licopersicon esculentum Mill.), onion (Allium cepa L.) and corn (Zea mays L.) has been limited by the high cost of F1 seed. To avoid this, producers have resorted to using F2, F3 ... seed. However, the inbreeding depression that this practice produces has led plant breeders to consider the synthetic varieties (SVs), particularly for cross-pollinated crops, which are not, however, without problems. In this work, the derivation of a SV whose parents are L lines and s single crosses (SynL,SC) is propo¬sed as a way of decreasing the parent number (originally L+2s lines) and thereby also the costs and work involved in prediction. However, the most important SynL,SC quality indicators must be known in order to make an objective assessment. Thus, the study objectives related to SynL,SC were to determine: 1) the inbreeding coefficient (FSynL,SC) and 2) the best combination of L and s values. The derivation of FSynL,SC was based on the replacement of the general genotype of the genotypic array of SynL,SC (GASynL,SC) by the coancestry between the individuals that contribute the genes that make up this genotype, and the best combination of L and s values was the one that produ¬ced the lowest inbreeding coefficient. From a fixed even number of L + 2s fully inbred and unrelated lines and from two decompositions of GASynL,SC, it was found that FSynL,SC={1+Ls/[2(L+s)2]}/(L+2s). By inspection of the formula, FSynL,SC reaches its minimum in two cases: when L = 0 and when s = 0. However, the use of (L+2s)/2 single crosses requires fewer resources for prediction.

 

ORGANO-MINERAL PRODUCTION OF TULIP (Tulipa gesneriana L.) FOR CUT FLOWERS

PRODUCCIÓN ORGANOMINERAL DE TULIPÁN (Tulipa gesneriana L.) PARA FLOR DE CORTE

María de las Nieves Rodríguez-Mendoza; Berenice Osorio-Rosales; Libia Iris Trejo-Téllez; Ana María Castillo-González; María de Lourdes Arévalo-Galarza

Keywords: cv. Golden Apeldoorn, organic fertilization, honey.

10.5154/r.rchsh.2011.17.023

Received: 2010-10-04
Accepted: 0000-00-00
Available online:
Pages:117-127

An evaluation was made of tulip plants (Tulipa gesneriana L.) cv Golden Apeldoorn under greenhouse conditions, with the application of Steiner solution in different concentrations, and the application of organic nutrients to the root (Aminofit Extra®) and to foliage (bee honey at 2 %). In the cut flower, differences were found in stem thickness, intensity of green in foliage and nutrient content among treatments. In vase life, the control plants lasted six days, those irrigated with Steiner solution (100 %), 12 days, and those with honey applied to the foliage, 15 days. It is concluded that the combination of Steiner solution at 100 % and foliar fertilization with honey increases flower quality.

An evaluation was made of tulip plants (Tulipa gesneriana L.) cv Golden Apeldoorn under greenhouse conditions, with the application of Steiner solution in different concentrations, and the application of organic nutrients to the root (Aminofit Extra®) and to foliage (bee honey at 2 %). In the cut flower, differences were found in stem thickness, intensity of green in foliage and nutrient content among treatments. In vase life, the control plants lasted six days, those irrigated with Steiner solution (100 %), 12 days, and those with honey applied to the foliage, 15 days. It is concluded that the combination of Steiner solution at 100 % and foliar fertilization with honey increases flower quality.

 

BIOCHEMICAL RESPONSES IN STRAWBERRY PLANTS SUPPLYING PHOSPHORUS IN THE FORM OF PHOSPHITE

RESPUESTAS BIOQUÍMICAS EN FRESA AL SUMINISTRO DE FÓSFORO EN FORMA DE FOSFITO

Elías Estrada-Ortiz; Libia Iris Trejo-Téllez; Fernando Carlos Gómez-Merino; Manuel Sandoval-Villa; Roberto Núñez-Escobar

Keywords: Fragaria x ananasa Duch.; total soluble sugars, chlorophyll, free amino acid; soluble proteins

10.5154/r.rchsh.2011.17.024

Received: 2010-08-27
Accepted: 2011-09-08
Available online:
Pages:129-138

In this study we evaluated the concentration of total soluble sugars, chlorophylls a, b and total during blooming stage and fructification stage, and free amino acids and soluble proteins during fructification stage, in strawberry leaves cv. Festival in response to the addition of P in the form of phosphite in different proportions (0, 20, 30, 40 and 50 %) in the nutrient solution. When 20 % of total P in the form of phosphite was added in the nutrient solution, the concentrations of sugars significantly increased only during the blooming stage. Content of chlorophyll a during blooming stage did not show significant differences among treatments containing phosphite with respect to the control treatment; on the contrary, during the fructification stage, the highest content of chlorophyll a, b, and total was recorded with the addition of 30 % of P as phosphite in the nutrient solution. Total free amino acids had a concentration positively related to the proportion of total P as phosphite in the nutrient solution in the range of 0 to 30 %; higher percentages of phosphite led to a decrease in free amino acids. A similar trend in the concentration of total soluble proteins was observed; variable in which the lowest mean in the control was registered; being significantly different to the treatment involving the addition of 50 % of P in the form of phosphite. These results led to the conclusion that the addition of 30 % of total P to the nutrient solution as phosphite stimulates the accumulation of biomolecules in strawberry plants during the fructification stage.

In this study we evaluated the concentration of total soluble sugars, chlorophylls a, b and total during blooming stage and fructification stage, and free amino acids and soluble proteins during fructification stage, in strawberry leaves cv. Festival in response to the addition of P in the form of phosphite in different proportions (0, 20, 30, 40 and 50 %) in the nutrient solution. When 20 % of total P in the form of phosphite was added in the nutrient solution, the concentrations of sugars significantly increased only during the blooming stage. Content of chlorophyll a during blooming stage did not show significant differences among treatments containing phosphite with respect to the control treatment; on the contrary, during the fructification stage, the highest content of chlorophyll a, b, and total was recorded with the addition of 30 % of P as phosphite in the nutrient solution. Total free amino acids had a concentration positively related to the proportion of total P as phosphite in the nutrient solution in the range of 0 to 30 %; higher percentages of phosphite led to a decrease in free amino acids. A similar trend in the concentration of total soluble proteins was observed; variable in which the lowest mean in the control was registered; being significantly different to the treatment involving the addition of 50 % of P in the form of phosphite. These results led to the conclusion that the addition of 30 % of total P to the nutrient solution as phosphite stimulates the accumulation of biomolecules in strawberry plants during the fructification stage.

 

VEGETATIVE, REPRODUCTIVE AND FRUIT YIELD CHARACTERISTICS OF "POBLANO" PEPPER LANDRACES

CARACTERÍSTICAS VEGETATIVAS, REPRODUCTIVAS Y DE RENDIMIENTO DE FRUTO DE VARIEDADES NATIVAS DE CHILE “POBLANO”

Higinio López-Sánchez; Pedro Antonio López; Juan de Dios Guerrero-Rodríguez; Amalio Santacruz-Varela; Arturo Huerta-de la Peña

Keywords: Capsicum annuum L., morphological characteristics, yield, Puebla, Mexico.

10.5154/r.rchsh.2011.17.025

Received: 2010-04-03
Accepted: 2011-09-12
Available online:
Pages:139-150

Besides its cultural importance, poblano pepper is a source of income and food for rural families of the region of Sierra Nevada in Puebla, Mexico. However, poblano pepper yield and cultivated land have decreased in the last year, due to factors as: landraces, frosts, pests and diseases, among other issues, which could lead to loss of genetic diversity. Nonetheless, little research has been done to solve its current problematic. Thus, the aim of this study was to evaluate the vegetative, reproductive and fruit yield characteristics of the native variety of poblano pepper from the region of Sierra Nevada in the state of Puebla, and to choose local cultivars for further breeding. A group of 49 landraces were evaluated using a triple 7x7 lattice design in two localities. According with the combined analysis, the traits that had significant differences among varieties were days to flowering /70 to 96), days to fructification (78 to 109), plant height (37.9 to 56.8 cm), plant width (24.1 to 44.3 cm), branching density (5.7 to 6.8), fruit weight (4.7 to 24.8 g) and fruit number (2.2 to 7.2). The 20 % outstand¬ing varieties had fresh fruit yield that ranged between 7.4 and 9.6 t•ha-1. The existence of morphological diversity in local poblano pepper landraces, expressed through the tested characteristics, could be integrated into plant diversity preservation and breeding programs.

Besides its cultural importance, poblano pepper is a source of income and food for rural families of the region of Sierra Nevada in Puebla, Mexico. However, poblano pepper yield and cultivated land have decreased in the last year, due to factors as: landraces, frosts, pests and diseases, among other issues, which could lead to loss of genetic diversity. Nonetheless, little research has been done to solve its current problematic. Thus, the aim of this study was to evaluate the vegetative, reproductive and fruit yield characteristics of the native variety of poblano pepper from the region of Sierra Nevada in the state of Puebla, and to choose local cultivars for further breeding. A group of 49 landraces were evaluated using a triple 7x7 lattice design in two localities. According with the combined analysis, the traits that had significant differences among varieties were days to flowering /70 to 96), days to fructification (78 to 109), plant height (37.9 to 56.8 cm), plant width (24.1 to 44.3 cm), branching density (5.7 to 6.8), fruit weight (4.7 to 24.8 g) and fruit number (2.2 to 7.2). The 20 % outstand¬ing varieties had fresh fruit yield that ranged between 7.4 and 9.6 t•ha-1. The existence of morphological diversity in local poblano pepper landraces, expressed through the tested characteristics, could be integrated into plant diversity preservation and breeding programs.

 

EVALUATION OF PRUNING IN TWO HUSK TOMATO (Physalis ixocarpa Brot. ex Horm.) VARIETIES CULTIVATED IN FIELD

EVALUACIÓN DE PODAS EN DOS VARIEDADES DE TOMATE DE CÁSCARA (Physalis ixocarpa Brot. ex Horm.) CULTIVADO EN CAMPO

Juan José Ponce-Valerio; Aureliano Peña-Lomelí; Felipe Sánchez-Del Castillo; Juan Enrique Rodríguez-Pérez; Rafael Mora-Aguilar; Natanael Magaña-Lira; Rogelio Castro-Brindis

Keywords: Yield, fruit quality, CHF1 Chapingo variety.

10.5154/r.rchsh.2011.17.026

Received: 2010-08-02
Accepted: 2011-09-21
Available online:
Pages:151-160,

This investigation was carried out during the spring - summer cycle of 2005. The purpose was to improve the quality and yield of husk tomato crop with pruning. The effect of four pruning levels (fourth inter node, sixth inter node, eighth inter node, and without pruning) was studied on two husk tomato varieties (CHF1 Chapingo, and Tamazula SM2). The experiment design was a randomized blocks with four replications, and treatments were arranged in a 4x2 full factorial design. The experimental unit was of 6 m2, 18 total plants, and 16 plants to measuring. The evaluated characteristics were fruit size (equatorial and polar diameter), fruit weight, and yield. Pruning had not positive effect on yield and fruit quality. The highest yield (963.5 g per plant) and better fruit quality (weight per fruit of 26.4 g, equatorial diameter of 54.4 mm, and polar diameter of 34.1 mm) were obtained with the CHF1 Chapingo variety.

This investigation was carried out during the spring - summer cycle of 2005. The purpose was to improve the quality and yield of husk tomato crop with pruning. The effect of four pruning levels (fourth inter node, sixth inter node, eighth inter node, and without pruning) was studied on two husk tomato varieties (CHF1 Chapingo, and Tamazula SM2). The experiment design was a randomized blocks with four replications, and treatments were arranged in a 4x2 full factorial design. The experimental unit was of 6 m2, 18 total plants, and 16 plants to measuring. The evaluated characteristics were fruit size (equatorial and polar diameter), fruit weight, and yield. Pruning had not positive effect on yield and fruit quality. The highest yield (963.5 g per plant) and better fruit quality (weight per fruit of 26.4 g, equatorial diameter of 54.4 mm, and polar diameter of 34.1 mm) were obtained with the CHF1 Chapingo variety.

 

MORPHOLOGICAL VARIABILITY BY MEANS OF SEED TRAITS OF POPULATIONS OF Amelanchier denticulate (Kunth) Koch, FROM GUANAJUATO, MEXICO.

VARIABILIDAD MORFOLÓGICA MEDIANTE CARACTERES DE SEMILLA DE POBLACIONES DE Amelanchier denticulate (Kunth) Koch, ORIGINARIAS DE GUANAJUATO, MEXICO

Miguel Ángel Hernández-Martínez; Carlos Alberto Núñez-Colín; Salvador Horacio Guzmán-Maldonado; Edgar Espinosa-Trujillo; María Guadalupe Herrera-Hernández

Keywords: Southern false serviceberry, Rosaceae subtribe Pyrinae, morphological variability, multivariate methods.

10.5154/r.rchsh.2011.17.027

Received: 2011-02-14
Accepted: 2011-09-21
Available online:
Pages:161-172

The Mexican serviceberry (Amelanchier denticulata (Kunth) Koch.) is a fruit-bearing shrub belonging with to the family Rosaceae subtribe Pyrinae, which is native to Mexico. There are no studies to know its diversity and its reproductive system. Furthermore, for having an insight of the morphological variability, six populations of A. denticulata from Guanajuato, Mexico, were characterized by means seed traits. All the populations showed high intra and inter-population variability. The analyzed seed traits were discriminating to distinguish the different populations mainly by traits related to the seed size, followed by the seed shape traits. The apomixis degree is not clear on this species due to the high intra-population variability. However, more detailed studies are needed to conclude whether or not apomixis is present in A. denticulata.

The Mexican serviceberry (Amelanchier denticulata (Kunth) Koch.) is a fruit-bearing shrub belonging with to the family Rosaceae subtribe Pyrinae, which is native to Mexico. There are no studies to know its diversity and its reproductive system. Furthermore, for having an insight of the morphological variability, six populations of A. denticulata from Guanajuato, Mexico, were characterized by means seed traits. All the populations showed high intra and inter-population variability. The analyzed seed traits were discriminating to distinguish the different populations mainly by traits related to the seed size, followed by the seed shape traits. The apomixis degree is not clear on this species due to the high intra-population variability. However, more detailed studies are needed to conclude whether or not apomixis is present in A. denticulata.

 

EVALUATION OF PITAYA PLANTS (Stenocereus spp) OF NATURAL POPULATIONS OF MONTE ESCOBEDO, ZACATECAS

EVALUACIÓN DE PLANTAS DE PITAYA (Stenocereus spp) DE POBLACIONES NATURALES DE MONTE ESCOBEDO, ZACATECAS

Eduardo Campos-Rojas; José Manuel Pinedo- Espinoza; Rafael German Campos-Montiel; Alma Delia Hernández-Fuentes

Keywords: Cactus, dragon fruit, postharvest.

10.5154/r.rchsh.2011.17.028

Received: 2011-02-03
Accepted: 2011-09-19
Available online:
Pages:173-182,

In Zacatecas, the pitayas (Stenocereus spp) exist in several municipalities where they are collected for local consumption, although in recent years, in the municipality of Monte Escobedo, Zac., it has become a crop of high prospects for commercialization. Therefore, in this work an evaluation was made of four phenotypes of pitaya (according to the color of the mature fruit: yellow, white, purple and red). The fruits were harvested in commercial maturity. The following were evaluated in the plant: stem diameter, plant height, number of shoots per plant and number of fruits per shoot. In the fruit, the following were evaluated: fruit weight, pulp weight, peel weight, polar diameter, equatorial diameter, firmness, total sugars, reducing sugars, pH, titratable acidity and protein content in seeds and pulp. Yellow pitayas exhibited greater plant height with respect to the purple and a height equal to that of white and red. The yellow pitayas had a greater number of shoots per plant compared with the white and red. With respect to stem diameter, the yellow pitaya was smaller than other phenotypes. The purple pitayas presented a higher number of shoots with fruit than the white and red varieties. Due to the characteristics of fruit length, weight of rind, pulp and fruit, firmness, total soluble solids, titratable acids, protein content in pulp and seed, the red pitaya fruits are an option with potential for production and commercialization.

In Zacatecas, the pitayas (Stenocereus spp) exist in several municipalities where they are collected for local consumption, although in recent years, in the municipality of Monte Escobedo, Zac., it has become a crop of high prospects for commercialization. Therefore, in this work an evaluation was made of four phenotypes of pitaya (according to the color of the mature fruit: yellow, white, purple and red). The fruits were harvested in commercial maturity. The following were evaluated in the plant: stem diameter, plant height, number of shoots per plant and number of fruits per shoot. In the fruit, the following were evaluated: fruit weight, pulp weight, peel weight, polar diameter, equatorial diameter, firmness, total sugars, reducing sugars, pH, titratable acidity and protein content in seeds and pulp. Yellow pitayas exhibited greater plant height with respect to the purple and a height equal to that of white and red. The yellow pitayas had a greater number of shoots per plant compared with the white and red. With respect to stem diameter, the yellow pitaya was smaller than other phenotypes. The purple pitayas presented a higher number of shoots with fruit than the white and red varieties. Due to the characteristics of fruit length, weight of rind, pulp and fruit, firmness, total soluble solids, titratable acids, protein content in pulp and seed, the red pitaya fruits are an option with potential for production and commercialization.

 

POROSITY-WATER RETENTION RELATIONSHIP IN SUBSTRATE MIXTURES AND ITS EFFECT ON RESPONSE VARIABLES IN LETTUCE SEEDLINGS

RELACIÓN POROSIDAD-RETENCIÓN DE HUMEDAD EN MEZCLAS DE SUSTRATOS Y SU EFECTO SOBRE VARIABLES RESPUESTA EN PLÁNTULAS DE LECHUGA

Ma. del Carmen Gutiérrez-Castorena; Jorge Hernández-Escobar; Carlos A. Ortiz-Solorio; Rosa Anicua-Sánchez; Ma. Encarnación Hernández-Lara

Keywords: Coir, volcanic stone, pumice, particle size, proportion of materials, micromorphology.

10.5154/r.rchsh.2011.17.029

Received: 2011-01-23
Accepted: 2011-09-27
Available online:
Pages:183-196

The relationship among porosity, size and particle distribution (1-2 mm and 2-3.36 mm) with water retention for different mixtures of materials: coir (Fc), stone (P) or volcanic stone (T), combined in variables proportions (0:100, 25:75, 50:50, 75:25 and 100:0 v/v) was studied. The effect of the combination Fc:P with a particle size (1-2 mm) on response variables in lettuce seedlings var. Summertime was analyzed. The water retention curve was determined. The types of pores and the particle distribution pattern of the mixtures was analyzed though thin sections. Porosity was quantified using an image analyzer. Results showed that Fc:T and Fc:P mixtures (75:25 v/v), showed the highest volumetric (98 %) and gravimetric (230 %) water retention capacity, as well as an anisotropic or heterogeneous pore system (macro and micro), and a band distribution, that allowed percolation and optimal water retention for the development of lettuce seedlings, represented in the best response variables and quality of root ball. In contrast, the rest of the mixture with an isotropic or homogeneous pore system, either simple or compound packing pores, and a basic random distribution of particles, generating more percolation or more water retention, that limited the growth of seedlings. Micromorphology can be useful for understanding the physical properties of the subs¬trates by directly determining the type, size and continuity of pores, characteristics that affect water-air availability.

The relationship among porosity, size and particle distribution (1-2 mm and 2-3.36 mm) with water retention for different mixtures of materials: coir (Fc), stone (P) or volcanic stone (T), combined in variables proportions (0:100, 25:75, 50:50, 75:25 and 100:0 v/v) was studied. The effect of the combination Fc:P with a particle size (1-2 mm) on response variables in lettuce seedlings var. Summertime was analyzed. The water retention curve was determined. The types of pores and the particle distribution pattern of the mixtures was analyzed though thin sections. Porosity was quantified using an image analyzer. Results showed that Fc:T and Fc:P mixtures (75:25 v/v), showed the highest volumetric (98 %) and gravimetric (230 %) water retention capacity, as well as an anisotropic or heterogeneous pore system (macro and micro), and a band distribution, that allowed percolation and optimal water retention for the development of lettuce seedlings, represented in the best response variables and quality of root ball. In contrast, the rest of the mixture with an isotropic or homogeneous pore system, either simple or compound packing pores, and a basic random distribution of particles, generating more percolation or more water retention, that limited the growth of seedlings. Micromorphology can be useful for understanding the physical properties of the subs¬trates by directly determining the type, size and continuity of pores, characteristics that affect water-air availability.

 

SHIFTING THE PERSIAN LEMON HARVEST SEASON

DESFASAMIENTO DE COSECHA DE LIMÓN PERSA

Gustavo Almaguer-Vargas; José Refugio Espinoza-Espinoza; José Luís Quirós-García

Keywords: Citrus latifolia, winter harvest, pruning, flower induction, blooming.

10.5154/r.rchsh.2011.17.030

Received: 2010-06-21
Accepted: 2011-09-27
Available online:
Pages:197-205

The concentration of the harvest in a period of the year is a great economical problem for growers because of the fall of prices when the offer increases. Winter harvest attains the best prices of the year, but they occur when the trees produce few fruits. With the aim of getting out-of-harvest season, several treatments were applied, including those involving branch pruning and application of urea to the foliage, in two orchards in Veracruz, México, one in Cuitlahuac and another in Tlalixcoyan, during November and December, respectively. In Cuit¬lahuac, branch pruning and foliar application of urea 5 % got 31.5 flowers per square meter, versus 7.6 % of the control, but the number of fruits was similar to the control, as well as fruit weight and total weight of fruits per tree. In Tlalixcoyan, pruning and foliar urea 10 % (T1) showed better results on blooming (118.75 flowers per square meter) than the control (6.5); greater (20.2) number of fruits per square meter than the control (2.33), and the highest values for harvestable fruits.

The concentration of the harvest in a period of the year is a great economical problem for growers because of the fall of prices when the offer increases. Winter harvest attains the best prices of the year, but they occur when the trees produce few fruits. With the aim of getting out-of-harvest season, several treatments were applied, including those involving branch pruning and application of urea to the foliage, in two orchards in Veracruz, México, one in Cuitlahuac and another in Tlalixcoyan, during November and December, respectively. In Cuit¬lahuac, branch pruning and foliar application of urea 5 % got 31.5 flowers per square meter, versus 7.6 % of the control, but the number of fruits was similar to the control, as well as fruit weight and total weight of fruits per tree. In Tlalixcoyan, pruning and foliar urea 10 % (T1) showed better results on blooming (118.75 flowers per square meter) than the control (6.5); greater (20.2) number of fruits per square meter than the control (2.33), and the highest values for harvestable fruits.