Survival and Growth of Seedlings of Three Sclerophyll Species at High Levels of Phosphorus and Nitrogen

1976 ◽  
Vol 24 (6) ◽  
pp. 681 ◽  
Author(s):  
RH Groves ◽  
K Keraitis

Seedlings of Banksia serrata, Acacia suaveolens and Eucalyptus pilularis were grown in sand culture for 3-4 months at four levels of phosphorus (0, 5, 50, and 100 ppm) and three of nitrogen (0, 25 and 250 ppm) applied gradually in all combinations. B.serrata died at high phosphorus-high nitrogen levels, A.suaveolens died with high phosphorus irrespective of the nitrogen level, and E. pilularis did not survive high phosphorus or high nitrogen levels. There were differences between species in their growth responses to increasing levels of phosphorus and nitrogen. Dry weights of seedlings were greatest at P5N25 for B.serrata, at P5N250 for A.suaveolens, and at P5N250 for E.pilularis. Shoot phosphorus concentrations greater than 1% were directly associated with 'toxicity' and death of A.suaveolens seedlings only, and not of the other two species. The species differ in the weights and nutrient contents of their seeds, and this is discussed in relation to the different responses obtained. Growth of sclerophyll species on areas subject to disturbance (e.g. sand-mining) will be determined in large part by the levels of phosphorus and nitrogen applied and the rate at which nutrients are leached from the rooting zone.

Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 308
Author(s):  
Yang Yu ◽  
Chunrong Qian ◽  
Wanrong Gu ◽  
Caifeng Li

Improving nitrogen use efficiency is a significant scientific problem to be solved. Two maize hybrids JD27 (Jidan 27) and SD19 (Sidan 19) were selected to study the effects of nitrogen levels on root characteristic parameters and plant dry matter accumulation, distribution and transportation. We set five different nitrogen levels, which were nitrogen deficiency (000N), low nitrogen (075N), medium nitrogen (150N), high nitrogen (225N) and excessive nitrogen (300N). The results showed that the root length and root surface area of JD27 were significantly higher than those of SD19 under 075N. With the increase of nitrogen levels, the root difference among varieties gradually decreased. The root length, projection area, total surface area and total volume reached the maximum values at silking stage. The average root diameter kept stable or decreased slowly with the growth stage. The dry matter accumulation of JD27 was higher than that of SD19 at all growth stages. Increasing the amount of nitrogen fertilizer can promote the transport of dry matter to grain and improve dry matter transport efficiency after anthesis. Under the treatment of medium and high nitrogen fertilizer, maize was easy to obtain a higher yield, but excessive nitrogen fertilizer inhibited the increase of yield. This study provides theoretical and practical guidance for maize production techniques.


2021 ◽  
Author(s):  
Minxia Liang ◽  
Liuqing Shi ◽  
David F. R. P. Burslem ◽  
David Johnson ◽  
Miao Fang ◽  
...  

2007 ◽  
Vol 136 (1) ◽  
pp. 56-71 ◽  
Author(s):  
Stephen M. Coghlan ◽  
Michael J. Connerton ◽  
Neil H. Ringler ◽  
Donald J. Stewart ◽  
Jerry V. Mead

2013 ◽  
Vol 35 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Krystyna Elkner

Empty cavities were found already in very young cucumber fruits with diameter 1.5 cm. As the fruit develops the empty cavities augment and the number of fruits showing this defect increases. Low soil moisture and high nitrogen fertilization favour the formation of empty cavities. Their origination and changes were traced with anatomical methods in the course of fruit development. As a most plausible cause of their origination the author considers the enlargement of only part of the cells of the suture between the two (or three) carples. Due to this uneven enlargement of neighbouring cells strong mechanical tension probably arises amoung them, leading to the formation of ruptures separating these cells, consequently causing the separation of the carpel edges. Besides that, some of the cells of the suture which have markedly enlarged, often burst which also contributes to the formation of an empty cavity and enlarges its dimensions.


2010 ◽  
Vol 34 (2) ◽  
pp. 435-442 ◽  
Author(s):  
Alberto C. de Campos Bernardi ◽  
Marisa Bezerra de Mello Monte ◽  
Paulo Renato Perdigão Paiva ◽  
Carlos Guarino Werneck ◽  
Patrick Gesualdi Haim ◽  
...  

Zeolites are hydrated crystalline aluminosilicate minerals of natural occurrence, structured in rigid third dimension net that can be used as slow release plant-nutrient source. The main objective of this study was to evaluate the effects of plant growth substrate under zeolite application, enriched with N, P and K, on dry matter yield and on nutrient contents in consecutive crops of lettuce, tomato, rice, and andropogon grass. The experiment was carried out in a greenhouse, with 3 kg pots with an inert substrate, evaluated in a randomized block design with three replications. Treatments consisted of four types of enrichment of concentrated natural zeolite: concentrated zeolite (Z) only, zeolite + KNO3 (ZNK), zeolite + K2HPO4 (ZPK) and zeolite + H3PO4 + apatite (ZP), and a control grown in substrate fertilized with a zeolite-free nutrient solution. Four levels of enriched zeolite were tested: 20, 40, 80, and 160 g/pot. Four successive crops were grown on the same substrate in each pot: lettuce, tomato, rice, and andropogon grass. Results indicated that N, P and K enriched zeolite was an adequate slow-release nutrient source for plants. The total dry matter production of above-ground biomass of four successive crops followed a descending order: ZP > ZPK > ZNK > Z.


2012 ◽  
Vol 168 (4) ◽  
pp. 834-850 ◽  
Author(s):  
Khalid Rehman Hakeem ◽  
Ruby Chandna ◽  
Altaf Ahmad ◽  
Mohd. Irfan Qureshi ◽  
Muhammad Iqbal

2005 ◽  
Vol 21 (4) ◽  
pp. 383-395 ◽  
Author(s):  
Silvia Iriarte Vivar Balderrama ◽  
Robin L. Chazdon

The dependence of tree seedling survival and growth on light availability was evaluated over 15 mo in three second-growth, wet forest stands (15–18 y old) in north-eastern Costa Rica. Seedlings of four canopy tree species (Dipteryx panamensis, Hyeronima alchorneoides, Virola koschnyi and Vochysia guatemalensis) were planted into four canopy treatments in three replicated stands and in a pasture site, spanning a nearly complete gradient of light availability. Survival and growth of all species increased in response to increasing light availability, but species differed in survival in shaded microsites (6–20% light transmittance) and in growth increments per light increase. Hyeronima showed the highest mortality at low light levels and the highest relative height growth increase per light increase. In contrast, Virola showed high survival at low and moderate light, but showed the lowest leaf area and above-ground biomass per light increase among all species. Dipteryx and Vochysia maintained relatively high rates of survival and growth across the entire light gradient. Hyeronima and Virola showed trade-offs between growth and survival responses to light, unlike Dipteryx and Vochysia. Differences among species in seedling survival at low light may be determined by a variety of physiological and morphological traits that may or may not be mechanistically linked to growth responses.


1958 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
LF Myers ◽  
J Lipsett

The effect of skeleton weed competition on the yield of wheat and oats was investigated in seasons when rainfall was plentiful. Nitrogen was found to be the major factor limiting crop yields. In soils with comparable nitrogen-supplying powers, skeleton weed density governed the crop's response to applied nitrogen. Competition between skeleton weed and crop was severe at low nitrogen levels, but minor at the high nitrogen levels achieved either by nitrogen application, or when the crop followed a legume-rich pasture. Competition had its effect early in the crop's growth. Temporary removal of competition, by spraying with plant growth regulating substances (JICPA) at different times, was used to determine when competition was critical, and measure its effects. Skeleton weed reduced nitrogen supply early in the crop's growth, and so depressed yield. An application of 1 lb MCPA per acre in the fallow 54 days before sowing, or 10 days after crop emergence, increased the yield of oats from 710 to 1350 lb grain per acre: a response equal to that from 32 lb nitrogen per acre applied at planting in the same experiment. In each case, the response to spraying at the different times was analogous to the effect of a nitrogen application at these times. Early spraying gave responses in yield; later spraying gave responses in grain nitrogen. The results provide a new estimate of the reduction in crop yield due to skeleton weed.


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