Use of Models as Non-destructive Method for Leaf Area Estimation in Horticultural Crops

Abstract

Leaf area estimation is an important biometrical trait for evaluating leaf development and plant growth analysis in field study of horticultural as well as other species of crop plants. These measurements can be made either destructively and/or non-destructively by using a variety of sensitive instruments as INTRODUCTIONCrop growth, productivity and quality are directly related to leaf area (LA) as leaves constitute the most important aerial organ of the plant, playing a major role in the photosynthetic assimilation by means of the light absorbing pigments (e.g., chlorophyll and carotenoids), which they possess in abundance. Hence, the total leaf area, which in the majority of cases has a direct bearing on the amount of chlorophyll, is an important parameter for assessing the ability of the plant to synthesize its dry matter (Prasada Rao et al., 1978). In addition, leaf area development strongly influences water and nutrient use of the horticultural crop plants and thus important for cultural management practices such as irrigation, fertilization, etc. It is also needed for evaluation of training and pruning systems and estimation of pest population densities in horticultural crops (Lang, 2005a;Anderson et al., 1999;Sepulveda and Kliewer, 1983; Elsner and Jubb, 1988; Lang, 2000b). A large number of methods, either destructive or not, have been developed to measure leaf area. However, measuring the surface area of a large number of leaves, especially in the field, can be costly, time consuming, laborious and usually destructive (Beerling and Fry, 1990). Many methods like tracing, blueprinting, photographing, or using a conventional planimeter, require the excision of leaves from the plants. It is therefore, not possible to make successive measurements of the same leaf. Also, the plant canopy is damaged, which might cause problems to other measurements or experiments (Lu et al., 2004). Non-destructive methods, which do not require the leaves to be detached, are useful because they allow measurements to be repeated during the plant"s growth period, and reduce the variability associated with destructive sampling procedures (Silva et al., 2005;Pandey and Singh 2011). Instruments and laser optic apparatuses have been developed for quick, accurate, and non-destructive measurement of leaf area (Daughtry 1990; Fladung and Ritter, 1991; Mori et al., 1991;Smith et al., 1991;Blanke, 1995;Ebert, 1995;Beverly and van Lersel, 1998; Igathinathane et al., 2006). However, these devices are somewhat expensive, time-consuming and complex (Manivel and Weaver, 1974;Robbins and Pharr, 1987) for basic and simple studies. A modelling approach involving linear relationships between LA and one or more dimensions of the leaf is an inexpensive, rapid, reliable and a nondestructive alternative for accurately measuring LA (Williams and Martinson, 2003; Lu et al., 2004). Thus for many fruit (Kobayashi, 1988;Potdar and Pawar, 1991; Uzun and Çelik, 1999;Campostrini and Yamanishi, 2001;Williams and Martinson, 2003;Demirsoy et al., 20...

Essential oil yield and yield components of basil (Ocimum basilicum L.) as affected by genotype and intrarow spacing at Jimma, SW Ethiopia

“…Leaf area per plant (cm 2 ) (LA) was measured according to the model available in the literature [17,18], which states:…”

Analysis of Cultivar-Specific Variability in Size-Related Leaf Traits and Modeling of Single Leaf Area in Three Medicinal and Aromatic Plants: Ocimum basilicum L., Mentha Spp., and Salvia Spp.

“…For instance, data on leaf characteristics can be incorporated into databases [11,12] and employed to validate time-series quantification of leaf morphology (e.g., [13,14]) and to determine the performance of computer-assisted imaging systems and machine learning algorithms used to classify/recognize phenotypic traits of specific genotypes [15].Leaf area is generally measured with destructive or non-destructive methods [16], the latter often preferred as they are faster, cheaper, and non-invasive (i.e., no excision of leaves is required), therefore, permitting repeated and simultaneous measurements of LA and other physiological parameters (e.g., leaf gas exchange or fluorescence) on the same leaves.Collected information, such as leaf blade length (L) and width (W) [17][18][19][20][21][22][23][24][25] or the shape ratio of the leaf (L:W) [26], can be useful for characterizing leaf functions and structure, based only on proxy variables. In particular, the leaf shape ratio is of particular importance in horticultural sciences as it is regulated by several genetic factors and mutations [27], whose diversity can be analyzed in functional [28] and evolutionary terms [29].Thus far, numerous models have been proposed and applied with respect to both leaf (e.g., [20,30,31]) and shoot level [31-41] morphology of several fruit, vegetable, ornamental, medicinal, and aromatic crops [42]. Currently, LA models for aromatic and medicinal plants comprise several species such as basil, winter red Bergenia, or purple bergenia, calamint, coffee, cherry laurel, bush-willows, jimson weed, wild cucumber, horse-eye bean, lemon balm, peppermint, oleander, mountain mint, opium poppy, ground-cherry, or winter cherry, picrorhiza or kutka, saffron, sugar leaf, snowbell, summer snowflake, tea, common nettle, orange mullein [42], valeriana [43], and pepper plants [44].The world production of medicinal and aromatic plants (MAPs) is expected to rise up to 5 trillion US$ by 2050 [45].…”

“…Thus far, numerous models have been proposed and applied with respect to both leaf (e.g., [20,30,31]) and shoot level [31-41] morphology of several fruit, vegetable, ornamental, medicinal, and aromatic crops [42]. Currently, LA models for aromatic and medicinal plants comprise several species such as basil, winter red Bergenia, or purple bergenia, calamint, coffee, cherry laurel, bush-willows, jimson weed, wild cucumber, horse-eye bean, lemon balm, peppermint, oleander, mountain mint, opium poppy, ground-cherry, or winter cherry, picrorhiza or kutka, saffron, sugar leaf, snowbell, summer snowflake, tea, common nettle, orange mullein [42], valeriana [43], and pepper plants [44].…”

Estimation of the Foliar Area by Non-Destructive Methods in Two Stages of Growth of Pepper Plants (<i>Capsicum annuum</i> L.) Hybrid Salvador

“…The main advantages of the use of allometric models for the estimation of the foliar area [6] [7] [8] are summarized in the following sections:…”

“…As a main disadvantage [6] it has been pointed out that an untrustworthy equation can create biases in the analyses derived from the models; so it is necessary to take into account the moments or stages for the measurement, which must correspond with the objectives of the studies that are intended to be carried out. It must be added that the sample must cover the entire range of values that will be used in the future; otherwise, the behavior of models outside the range for which they were built would be unknown.…”