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It has previously been shown that the induction medium influences embryogenesis and embryo morphology in pecan (Carya illinoensis). The objective of this study was to evaluate the effect of embryo morphology on germination and conversion into plants. Pecan somatic embryos induced on modified WPM with NAA or 2,4-D were categorized into three classes according to morphology: embryos with evident apex and well formed cotyledons; embryos with weak or no apex, with or without distinct cotyledons; and abnormal embryos. Embryos were given conversion-enhancing treatments which included cold treatment for eight weeks, followed by desiccation for five days. The embryos were then transferred to modified WPM with 10mg/l silver nitrate and 5mg/l gibberellic acid. The conversion of embryos was rated based on presence of leaflets and roots. Embryos germinated in all three classes. Conversion was markedly affected by embryo morphology; higher conversion rates were obtained with embryos which more closely resembled the zygotic morphology.
Abstract
There has recently been a resurgence in interest in the photosynthetic efficiency of apple (Malus domestica Borkh.) trees. During the 1930’s and early 1940’s several papers were published relating to leaf morphology and the effects of various factors such as water relations, nutrition, and pesticides on net photosynthesis (Pn) of apple leaves. From the mid 1940’s until the mid 1960’s little relevant research was published. Renewed emphasis began to be apparent by the mid 1960’s, partially as the result of greatly improved equipment, particularly the infrared gas analyzer (IRGA). This discussion is devoted to the maximum net photo synthetic potential of apple leaves, the factors which have been shown to influence it, and areas which need further research if we are to fully exploit the inherent capability for CO2 fixation.
Abstract
Total root biomass of 23 field-grown cultivars of tomato (Lycopersicon esculentum Mill.) was partitioned into basal-root and taproot components during Fall 1980 and Spring 1981. Weights of basal roots (originating within the lower one cm of the hypocotyl and one cm of the upper taproot) differed among cultivars during both seasons. For each cultivar, basal roots contributed the largest proportion of the total root biomass. No difference in taproot weights occurred among cultivars. Adventitious roots were minimal and were not measured. ‘Market Hybrid 58’ and ‘Casino Royale’ had larger total and basal root weights than ‘Burgis’, ‘Florida 1A’, and ‘Florida IB’ during both seasons. Stem diameter was significantly correlated with total and basal root weights. Results suggest that root morphological differences among tomato cultivars are restricted to basal roots.
Abstract
Some morphological aspects of navel oranges [Citrus sinensis (L.) Osbeck] were studied in 1980 and 1981 on healthy fruit and fruit affected by secondary-fruit yellowing (SFY), stylar-end decay (SED), and fruit splitting, major causes of summer and summer-fall fruit drop in Florida. Fruit affected by SED or splitting were generally larger and had larger styler-end apertures, and those affected by SED had a higher frequency of rind protrusions into primary-fruit locules than healthy fruit. Healthy fruit harvested from the south top of trees were heavier and had larger secondary fruit, stylar-end apertures, and thicker peel than fruit from the northern-bottom canopy position. Some of these characteristics are associated with incidence of SFY, SED, and fruit splitting.
Frequent winter injury to flower buds is a major deterrent to the widespread landscape use of evergreen azaleas in the northern United States and southern Canada. Field observations indicate that azalea cultivars differ greatly in their capacity for cold acclimation during the fall. Azaleas also express wide variation in morphological features, such as Ieaf number, density, percent abscission, twig Iength, flower bud development rate, number or bud scales, and petal color. We attempted to correlate these characteristics with the establishment of flower bud cold tolerance during the fall season. Young (3-year-old) plants of more than 60 azalea cultivars were investigated under nursery conditions. Twigs were subjected to controlled freezing to quantify frost tolerance of flower buds. Percent live florets per bud and number of dead florets per bud were correlated with morphological characters. Floret development (floret Iength and style Iength) correlated positively with cold acclimation. Stem and Ieaf characters showed no consistent correlation with bud cold tolerance. Petal coloration, although not expressed at time of study, also correlated with cold acclimation. The extent of flower bud development proved to be the best indicator of fall and early winter frost tolerance.
Fruit weight and morphological characteristics of `Meeker' red raspberry (Rubus idaeus L.) fruit, including drupelets (height, diameter, number), receptacle cavities (depth, diameter), and pits (individual weight) were measured five times in 1988. Fruit strength, as measured by compression, was recorded. The relationship of fro-it weight to fruit strength had linear and quadratic components. Fruit weight was correlated with fruit strength, drupelet height and number, receptacle cavity depth and diameter, and individual pit weight. Besides fruit weight, fruit strength was correlated with drupelet diameter and number, receptacle cavity depth, and individual pit weight. Drupelet number, receptacle cavity depth, and individual pit weight provided the largest component contribution to fruit strength, as determined by path analysis.
Weight and morphological characteristics of red raspberry (Rubus idaeus L.) fruit, including drupelets (height, diameter, number), receptacle cavities (depth, diameter), and pits (individual weight), were measured on 78 seedlings from the cross `Chief' × `Chilliwack'. Fruit strength, as measured by compression, correlated with fruit weight, drupelet number, receptacle cavity depth, and individual pit weight. Fruit weight was positively correlated with all morphological characteristics. Individual pit weight, drupelet height, and drupelet number provided the largest component contributions to fruit strength as measured by path analysis.
Tree peony cultivars are usually classified according to flower characteristics (flower form and flower color) which are commonly affected by environmental influences and developmental levels. Judgment of flower forms may also depend on the observer. Precise and rapid cultivar identification methods are also required to manage cultivar collections as well as tree peony breeding programs. The objective of this paper is to analyze the discriminatory ability of leaf morphology and Intersimple sequence repeat (ISSR) marker systems for tree peony cultivars. As a result, although there exist large variations of leaf morphology of tree peony cultivars, the morphological characteristics of biternately compound leaves 3, 4, and 5 from the base of a shoot at the middle part of a plant are relatively stable with smaller variations within cultivars (2.7% to 27.1%, 16.8% on average) and with larger differentiations among cultivars (72.9% to 97.3%, 83.2% on average). Statistical and principal components analyses indicate that 12 leaf morphological characteristics are valuable for cultivar classification. ISSR markers present a precisely discriminatory power in tree peony cultivar classification without environmental influences. The cultivars with multiple flower forms, which makes it difficult to make judgment by means of a flower-form-based classification system, have been significantly characterized using leaf morphology or ISSR markers.
known whether this is related to their improved roots. An accurate comprehension of alterations in root morphology and function is paramount to clarifying the influence of rhizosphere bacteria on plants. The volatile organic compounds (VOCs), which are
because of increased environmental concerns ( Bergstrand, 2017 ). In recent years, light spectral quality has been used as an alternative for modifying plant morphology for different production purposes, especially in controlled environments ( Clifford et