Effects of thinning after anthesis on groundnut growth, yield and yield components

This experiment was carried out to study groundnut (Arachis hypogaea L.) response to enhanced penetration of photosynthetically active radiation (PAR) into the canopy during reproductive growth in southeast Queensland, Australia. The experiment was located at the University of Queensland's Redland Bay Farm. Two groundnut cultivars (Improved Virginia Bunch and Red Spanish) were grown at a population of 42 plants m-2) and thinned at intensities of either 0% (control), 33%, 50%, 66% or 75% after anthesis (42 days after planting). The results show that thinning reduced PAR intercepted during reproductive growth, but slightly increased radiation use efficiency (Ec) with 33% plant removal in Red Spanish. Removal of either 0%, 33% or 50% of plants resulted in relatively similar total dry mass (TDM) and economic yields at maturity. Dry mass partitioning to reproductive sinks was largely unaffected by thinning after anthesis. It is concluded that removal of up to 50% of groundnut plants from the initial population of 42 m-2 after anthesis did not significantly reduce TDM or economic yield at maturity.Cette exp\ue9rimentation a \ue9t\ue9 effectu\ue9e en vue d'\ue9tudier la r\ue9action de l'arachide (Arachis hypogea L.) \ue0 la p\ue9n\ue9tration intense de la radiation photosynth\ue9tiquement active (PAR) dans la canopie pendant la croissance reproductive au sud-est de Queensland en Australie. L'exp\ue9rimentation a eu lieu \ue0 la ferme de Redland Bay de l'Universit\ue9 de Queensland. Deux cultivars de l'arachide (l'\ue9rig\ue9 am\ue9lior\ue9 de Virginie et l'Espagnol Rouge) ont pouss\ue9 jusqu' \ue0 une population de 42 plantes/m2. Ils ont \ue9t\ue9 ensuit\ue9 soumis au d\ue9mariage \ue0 0% (temoin), 33%, 66% ou 75% apr\ue8s l'anth\ue8se (42 jours apr\ue8s le s\ue9mis). Les r\ue9sultats montrent que le d\ue9mariage reduisait le PAR intercept\ue9 pendant la croissance reproductive mais augmentait l\ue9g\ue8rement l'efficacit\ue9 de la radiation utilis\ue9e (Ec) avec un d\ue9mariage de 33% des plantes pour le cultivar Espagnol Rouge. Le d\ue9mariage de 0%, 33% ou 50% des plantes aboutit \ue0 une masse totale s\ue8che (TDM) et aux rendements \ue9conomiques assez semblables \ue0 la maturit\ue9. La r\ue9partition de la mati\ue8re s\ue8che dans le bloc de stockagede la reproduction n'\ue9tait pas vraiment affect\ue9e par le d\ue9mariage apr\ue8s l'anth\ue8se. Il en r\ue9sulte qu'un d\ue9mariage d'un maximum de 50% des plantes d'arachide \ue0 partir d'une population initiale de 42/m2 apr\ue8s l'anth\ue8se ne r\ue9duitsait pas de fa\ue7on significative la mass s\ue8che totale (TDM) ou le rendement \ue9conomique \ue0 la maturit\ue9

Calcium nutrition of peanut grown in solution culture. I. genetic variation in Ca requirements for vegetative growth

Calcium (Ca) deficiency is an important problem in peanut (Arachis hypogaea L.) production, with lines from the sub-species A. hypogaea hypogaea (Virginia type) being considered more susceptible to Ca deficiency than those of A. hypogaea fastigata (Spanish and Valencia types). Fifteen peanut lines comprising five Virginia bunch, one Virginia runner, six Spanish, two Valencia types, and one Valencia × Spanish cross were grown for 30 d in continuously flowing solution culture at constant external Ca concentrations ranging from 9 to 2500 μM. Two lines required 75 μM Ca for maximum growth. The Ca concentration in the youngest fully expanded leaves required for maximum growth also differed considerably among the lines, ranging fro

Role of root cation-exchange capacity in differential aluminum tolerance of lotus species

Three experiments were conducted in which roots of two species of Lotus were immersed for up to 40 min in complete nutrient solutions containing 6, 15 or 25 pM Al. The two species tested were L. pedunculatuscv. Grasslands Maku (Al-tolerant) and L. corniculatus cv. Maitland (Al-sensitive). There was an initial rapid (< 5 min) decrease in solution Al at 25 pM Al. The effect was less marked with solution Al ≤ 15 μM. The decrease in solution Al was greater in the Al-sensitive Maitland than in the Al-tolerant Grasslands Maku, particularly when expressed on the basis of root fresh mass and root length. Root cation-exchange capacity (CEC) was lower in Grasslands Maku than in Maitland, viz. 23.9 vs 36.5 mmol kg -1 dry mass. Maitland roots removed more Al from solution than did those of Maku on the basis of total exchange capacity