Response of Beans to Shading¹

Abstract

Two dry bean (Phaseolus vulgaris L.) cultivars were grown in controlled‐environment chambers under standard light [390 μ Einsteins m‐2 sec‐1 (400 to 700 nm) = approx. 22,000 lux] and shaded light [55 μ Einsteins m‐2 sec‐1 (400 to 700 nm) = approx. 3,200 lux] intensities. Experimental observations included measurement of gas exchange and photosynthetic and respiratory enzyme activity along with examination of plant morphology, leaf anatomy, and chloroplast ultrastructure.Shading reduced leaf number, area, and thickness. Photosynthesis/unit area of shaded leaves was decreased by an average of 38%. Transpiration was not significantly affected. Increased intracellular resistance of the shaded leaves was more important in reducing CO2 uptake than was the increase in stomatal resistance. The increase in mesophyll resistance was reflected both in the biochemical reactions of the leaf (activity of all measured enzymes being reduced by 70%) and in the ultrastructure of the leaf chloroplasts (reduced quantities of starch in spite of extensive grana).

Leaf Characteristics and Yield Performance of Mungbean (<i>Vigna radiata</i> L.) Varieties under Different Levels of Shading

“…Islam (1995) in mungbean and Crookston et al (1975) in dry bean also found decreased leaf number under shade condition. Similar result of decrease in leaf number due to shading was found in all legumes by Chiangmai et al (2013).…”

“…Crookston et al (1975) reported that shading reduced leaf thickness of bean. Similar result of shading induced reduced thickness was found in all legumes by Chiangmai et al (2013) and Araki et al (2014).…”

Shoot Heterogeneity Effects on Shiraz/Richter 99 Grapevines. I. Vegetative Growth

“…While studying beans (Phaseolus vulgaris L.), Crookston et al (1975) found that shading decreased the thickness of leaves as well as the photosynthetic activity per unit leaf area. This was ascribed to the sharp increase in mesophyll resistance, which they linked to the decreased enzymatic activity and alterations in leaf anatomy and chloroplast ultrastructure also found.…”

The Effect of Light and Water Supply on Growth, Net CO2 Assimilation Rate and Mineral Content of Salak (Salacca zalacca (Gaertn.) Voss) Seedlings

“…This was due to the limitation of P N by low photosynthetic photon flux density. The mesophyll resistance, which is usually regarded as the sum of biophysical and biochemical resistances to CO 2 movement between the mesophyll cell wall and the site of carboxylation in the chloroplast, was reported to be higher in plants grown at low light intensities (Holmgren, 1968, Crookston et al, 1975.…”