Effects of sowing time and sowing density on the growth of subterranean clover at Adelaide

1977 ◽  
Vol 28 (3) ◽  
pp. 427 ◽  
Author(s):  
JH Silsbury ◽  
S Fukai

Growth curves have been constructed for undefoliated swards of subterranean clover (cv. Woogenellup) established at three plant densities (1,2 and 4 x l03 plants per m2) at three times of the year (May, June and August). The swards grew without any apparent water stress, until early December. The time course of shoot dry matter increase is examined by the use of a logistic function and by the recognition of three growth stages. Maximum crop growth rates ranged from 10 to 15 gm-2 day-1. The rate decreased with increase in density but increased with lateness of sowing, so that the highest crop growth rate was obtained with the lowest plant density sown in August. Estimated end-of-season yields were independent of density but decreased from about 1500 g m-2 for May sowing to 1000 g m-2 for August sowing. Effects of sowing density on the growth pattern persisted throughout the whole season. Swards took 70–100 days to attain a leaf area index (LAI) of 3, after which crop growth rates were almost constant with time and independent of short-term fluctuations in the level of daily solar radiation and average daily temperature. Swards reached a maximum LAI of about 6, LAI being linearly related to the amount of shoot dry matter up to about 600 gm-2 independent of density and sowing time. No evidence was found of an optimal relationship between crop growth rate and LAI.It is concluded that end-of-season yield is independent of plant density above 1000 established plants per m2, and that swards established as late as August have the capacity to attain a yield of 10 tonnes ha-1 provided the growing season is extended.

1975 ◽  
Vol 26 (1) ◽  
pp. 31 ◽  
Author(s):  
KS Fischer ◽  
GL Wilson

Growth analysis was applied to grain sorghum (cv. RS610) grown at low, medium and high population densities, i.e. 14,352, 143,520 and 645,836 plants ha-1 respectively. The medium densities had two arrangements of plants, square (S) and rectangular (R). Crop growth rates, inflorescence growth rates, leaf area indices, net assimilation rates and leaf growth rates were calculated from growth functions of plant dry matter and leaf area over time. Differences in crop growth rate between populations in the early stages were attributed to leaf area development—specifically to the initial leaf area (dependent on seedling number) and not to differences in leaf growth rates. Peak crop growth rates were 15.0, 27.5, 26.0 and 45.8 g m-2 day-1 for the low, medium (S), medium (R) and high populations respectively.The large difference between the growth rates of the medium (S) and the high populations was not explained by differences in the amount of radiation intercepted. Although leaf area indices were 4.6 and 10.2 respectively for the two populations, both canopies intercepted almost all of the noon radiation. Light extinction coefficients were 0.45 and 0.29 respectively. The relationship between net assimilation rate and leaf area index was such that for comparable leaf area indices above 2, plants at higher densities showed greater improvement in yield per unit increment in leaf area index. A maximum grain yield of 14,250 kg ha-1 was obtained at the high population density as a result of higher dry matter production, but a similar harvest index to that of the crops grown at the other densities. Inflorescence growth rate (g m-2 day-l) slightly exceeded crop growth rate in the latter part of grain filling, which indicated that there was some retranslocation to the grain of previously assimilated material. The maximum grain yield represents an efficiency of utilization of short-wave solar radiation during crop life of 2.5 x 10-6g cal-1. *Part IV, Aust. J. Agric. Res., 26: 25 (1975).


1973 ◽  
Vol 9 (2) ◽  
pp. 169-180 ◽  
Author(s):  
R. H. V. Corley

SUMMARYCrop growth rate of oil palm increases with leaf area index (LAI) to about 40 tons/ha./yr at the highest LAIs obtained. Net assimilation rate and dry matter production per palm decrease with increasing LAI, but the amount of dry matter per palm incorporated in vegetative tissues is unaffected by density. As a result the optimal LAI for oil yield is considerably below the critical LAI for maximum crop growth rate.


1963 ◽  
Vol 14 (1) ◽  
pp. 20 ◽  
Author(s):  
JN Black

The relationship of crop growth rate, leaf area index, and solar radiation has been examined for swards of subterranean clover, of the variety Bacchus Marsh. Leaf area index was varied by growing swards at eight densities of sowing, and radiation varied by two levels of shading, in addition to full daylight; the whole experiment was done three times—in summer, early winter, and spring—at the Waite Agricultural Research Institute, Adelaide. Crop growth rate was measured as the difference between the dry weights of the swards on two harvest occasions, and was calculated from smoothed values obtained by fitting an appropriate equation to the yield : density relationship. Thus a set of nine curves were available, each showing the response of growth rate to varying leaf area index at a specific level of radiation. These nine curves formed a consistent series, the growth rate rising with leaf area index until a maximal value was reached at the "optimum leaf area index", thereafter falling. At low levels of radiation, growth rate fell to zero at high leaf area indices. Both the maximal growth rate and the optimum leaf area index increased with radiation, and an analysis of the data indicated that these growth indices were dependent on radiation, the effect of temperature being negligible. A generalized series of curves was calculated by extrapolation, so that crop growth rates can be derived for any combination of leaf area index and radiation. A comparison of maximal crop growth rates and percentage utilization of light energy of subterranean clover and other crops suggests that this clover is relatively inefficient in integrating its environment.


2017 ◽  
Vol 14 (2) ◽  
pp. 147-154 ◽  
Author(s):  
MM Kamrozzaman ◽  
MAH Khan ◽  
S Ahmed ◽  
N Sultana

An experiment was conducted at Sadipur charland under Farming System Research and Development Site, Hatgobindapur, Faridpur, during rabi season of 2012-13 and 2013-14 to study the growth and yield performance of cv. BARI Gom-24 as affected by different dates of sowing under Agro-ecological Zone-12 (AEZ-12) of Bangladesh. The experiment was laid out in randomized complete block design with six replications, comprising five different dates of sowing viz. November 5, November 15, November 25, December 5 and December 15. Results reveal that the tallest plant, leaf area index, total dry matter, and crop growth rate were observed in November 25 sown crop and leaf area index, total dry matter and crop growth rate were higher at booting, grain filling, and tillering stages of the crop. Maximum effective tillers hill-1 (3.49), spikes m-2, (311), number of grains spike-1 (42.20) and 1000-grain weight (52.10 g) were produced by November 25 sown crop exhibited the highest grain (4.30 t ha-1) and straw yield (4.94 t ha-1) as well as harvest index (46.88%) of the crop. Lowest performance was observed both in early (November 5) and late sown crop (December 15). The overall results indicated that November 25 sown crop showed better performance in respect of growth and yield of wheat under charland ecosystem of Bangladesh.J. Bangladesh Agril. Univ. 14(2): 147-154, December 2016


1979 ◽  
Vol 30 (1) ◽  
pp. 53 ◽  
Author(s):  
JH Silsbury ◽  
L Adem ◽  
P Baghurst ◽  
ED Carter

Shoot dry matter yield data for swards of Medicago truncatula cv. Jemalong established on two occasions at Adelaide in 1975 have been used to examine the influence of sowing rate on the seasonal growth pattern of this species. The patterns of dry matter growth are assessed: (i) by the use of a logistic function; (ii) by a growth stage approach involving an initial phase of approximately exponential growth (stage I) followed by a phase of almost constant growth rate (stage II). Two methods are given for determining the duration of these stages. It was found that stage I1 began at a shoot dry weight of about 300 g m-2, irrespective of sowing rate. End-of-season yield at about 10 t ha-1 was largely independent of sowing time and of sowing density. A maximum crop growth rate of 14.9 g m-2 d-1 was recorded for low density and late sowing. Sowing density had a marked effect on the shape of the growth curves; both the maximum crop growth rate and the average crop growth rate in stage II decreased with increase in sowing rate for each time of sowing.


Author(s):  
A. Reshma ◽  
P. Latha ◽  
V. Umamahesh ◽  
R. P. Vasanthi ◽  
P. Sudhakar

Groundnut is grown during July to October in kharif season, however area under early kharif (sowing in May) is increasing in Andhra Pradsh, where ever irrigation facilities exists. Hence to identify suitable variety for the situation, fourteen pre release and two released groundnut genotypes were evaluated during early kharif 2013 for growth, physiological traits and yield attributes. At harvest genotypes TCGS-1375 (41.331 g plant-1), TCGS-1342(41.059 g plant-1) significantly recorded higher total dry matter compared to all other cultivars and checks followed by TCGS-1330 (36.667 g plant-1), TCGS-1349 (36.433 g plant-1). TCGS-1342 recorded significantly higher Crop Growth Rate (CGR) value of 33.848 g m-2 day-1, where as TCGS-1346 (0.1265 g dm-2 day-1) and TCGS-1330 (0.1262 g dm-2 day-1) recorded significantly higher Net Assimilation Rate (NAR) values at 45-60 DAS. Cultivar, TCGS-1330 recorded significantly higher pod yield 4210.44 Kg ha-1 compared to other entries and checks. The results revealed that pre release genotypes, TCGS-1342, TCGS-1375, TCGS-1330, TCGS-1346 recorded high physiological efficiency in terms of growth and physiological traits viz. total dry matter (TDM), crop growth rate (CGR), net assimilation rate (NAR) and leaf area index (LAI) and also recorded high pod yield.


Author(s):  
D. Dev Kumar ◽  
D. Vishnu Vardhan Reddy ◽  
P. Raghuveer Rao ◽  
M. Sheshu Madhav ◽  
V. Gouri Shankar

The experimental field was laid in RBD replicated thrice with 30 high yielding rice genotypes which includes 26 advanced breeding lines (ABL) (SP-351, SP-352, SP-353, SP-354, SP-355, SP-356, SP-357, SP-358, SP-359, SP-360, SP-70, SP-72, SP-63, SP-61, SP-69, SP-55, SP-80, SP-25, SP-13,  SP-03, SP-02, SP-34, SP-37, SP-08, SP-75 and SP-57) and four checks (NDR-359, BPT-5204, IR-64, Jaya). Seven genotypes showed significantly higher leaf weight over the BPT-5204. Further, leaf weight at panicle initiation stage showed a positive relationship with TDM (Total Dry Matter) (r=0.51**). At the panicle initiation stage, only three genotypes (SP-354, SP-358, and SP-72) were superior to BPT-5204 in leaf weight. The shoot biomass and total dry weight was superior only in one genotype SP-72 as compared to BPT-5204. Similarly, the net assimilation rate at panicle initiation stage was maximum in SP-08 (9.92g m-2 day-1) and SP-72 (9.35g m-2 day-1) as compared to check BPT-5204 (6.47g m-2 day-1). These genotypes maintained higher photosynthetic rate (SP-72) and higher grain yield (SP-08). The relationship between CGR (Crop Growth Rate) and TDM (Total Dry Matter) and grain yield (r=0.61**) was positive and significant at physiological maturity. Genotypes SP-08 and SP-72 showed significantly higher CGR (Crop Growth Rate) over BPT-5204 and hence, yielded higher. In the present study compared to BPT-5204, genotypes SP-72, SP-08 maintained higher lea area index at all crop growth stages. These genotypes maintained higher photosynthetic rate (SP-72) and higher grain yield (SP-08). Positive significant relationship between LAI (Leaf Area Index) and total dry matter at harvest and; grain yield has been observed.


2021 ◽  
Vol 52 (5) ◽  
pp. 1207-1218
Author(s):  
J. J. Kadhim ◽  
J. H. Hamza

A field experiment was carried out during two spring seasons in 2019 and 2020. This study was aimed to increase dry matter weight and crop growth rate of maize. First factor in main plots was nutrition vegetative parts with ascorbic and citric (100 mg l-1) for both of them and humic (1 ml l-1), in addition to the control treatment (spraying of vegetative parts with distilled water only). Second factor in sub-plots was seeds soaking with same acids above, as well as the control treatment (soaking the seeds with distilled water only). Randomize complete block design in split plot arrangement was used with three replications. The results showed a significant superiority of seeds soaking in humic acid for traits of number of days from planting to 75% anthesis  and silking (66.4 and 66.3 day) and (72.3 and 72.3 day), plant height (194.0 and 230.8 cm), leaves area plant-1 (6969.5 and 6570.2 cm2), leaf area index (3.71 and 3.50), dry matter weight (11.6 and 12.2 ton ha-1), crop growth rate (3.0 and 3.2 g cm-2 day-1) and chlorophyll leaf content (60.2 and 69.5 SPAD) for both seasons, respectively. Effect of vegetative parts nutrition and interaction effect of both studied factors was non-significant for most traits. It can be concluded that seeds soaking in humic acid improved growth traits. It can be recommended to soak seeds of maize before planting in humic acid at concentration of 1 ml l-1.


1978 ◽  
Vol 29 (1) ◽  
pp. 51 ◽  
Author(s):  
S Fukai ◽  
JH Silsbury

A simple deterministic model to simulate the time course of potential dry matter growth by subterranean clover swards in the field is described. Relationships used in the model were obtained mainly from experiments in temperature-controlled glasshouses and from measurements of rate of carbon dioxide exchange in an assimilation chamber. Canopy carbon dioxide exchange rates in the light and in the dark are calculated in the model from leaf area index, total dry matter, air temperature, irradiance and the crop growth rate of the sward. Photosynthates are distributed among different parts of plants according to empirical relationships. The model can estimate the potential dry matter growth of swards grown at different levels of irradiance and at different temperatures. Dry matter yield of a crop growing in the field without limitation of water and mineral nutrients can be predicted to within 20% for 100 days of growth. Potential dry matter yield of pure subterranean clover swards at Adelaide is predicted by the model to be strongly influenced by the time of cessation of growth. If the growth is terminated in the middle of October, an early start to growth as well as a high plant density will be advantageous for a high final yield. On the one hand, if the growing season extends until late November, there will be only a small effect of time of commencement of growth on final yield. The model suggests that leaf area index is an important determinant of dry matter production up to about 200 g m-2, and that increased maintenance respiration at a dry matter yield above about 600 g m-2 results in a decreased growth rate. The effects of variation in irradiance and temperature on dry matter production at different growth stages are assessed. It is concluded from use of the model that the effects of temperature on crop growth rate depend on the amount of dry matter present and on the level of solar radiation.


1993 ◽  
Vol 29 (4) ◽  
pp. 491-501 ◽  
Author(s):  
M. J. Bell ◽  
G. C. Wright ◽  
G. Harch

SummaryThe partitioning of dry matter between vegetative and reproductive yield components was analysed for four diverse peanut cultivars at a range of sowing dates and plant populations in sub-tropical Queensland, Australia. Rates of accumulation of pods (pod addition) varied significantly with both cultivar and sowing date. Within cultivars, much of this variation could be attributed to variation in crop growth rate during the critical pod addition period. The proportion of current assimilate distributed to pods depended on inherent cultivar characteristics and also correlated well with the current crop growth rate relative to the crop growth rate during pod addition (that is, with relative source activity). Neither plant density nor spatial arrangement had any significant effects on patterns of assimilate distribution. All cultivars appeared capable of remobilizing stored assimilate to maintain constant rates of pod yield increase despite fluctuations in crop growth rate which might be expected to produce short term source limitations to pod yield accumulation. The harvest index (HI) increased linearly during the entire pod fill period in all cultivars except the very early maturing Spanish cultivar Chico. Neither density nor spatial arrangement affected rate of increase in HI except in Chico, where increased density produced increased rates of increase in HI. Variation in the rate of HI increase among sowing dates was small.Distributión de la materia seca en el maní


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