Measurement of net leaf photosynthesis in physiological field research:

• The Infrared Gas Analyzer (IRGA, such as LI-COR LI-6400/LI-6800) is a portable field instrument that accurately quantifies photosynthetic rate and stomatal conductance.
• It measures differential differential absorption of infrared light by $\text{CO}_2$ ($4.26\text{ }\mu\text{m}$) across an open or closed leaf chamber, recording the depletion of $\text{CO}_2$ as carbon assimilation occurs.

Plant diagnostic symptoms of iron deficiency:

• Iron (Fe) is structurally immobile within plant phloem tissue and cannot be readily remobilized from older leaves to growing shoot apices.
• Consequently, deficiency symptoms invariably develop first on the youngest expanding leaves, presenting as distinct interveinal chlorosis (the leaf lamina turns pale yellow/white while the veins remain distinctly green).
• In contrast, mobile nutrients (like Mg) show interveinal chlorosis on older leaves first.

Monocarpic senescence in plants:

• Monocarpic plants flower and produce seeds only once in their lifetime and then undergo complete whole-plant senescence and death.
• While most monocarpic plants are annuals (wheat, rice) or biennials (carrot), certain long-lived perennial plants such as Bamboo (Bambusa spp., flowering synchronously after 30 to 120 years of vegetative growth) and Agave americana (Century plant) exhibit perennial monocarpic senescence.
• Teak, mango, and mulberry are polycarpic perennials that flower and fruit repeatedly year after year.