Groei en ontwikkeling van sojabooncultivars by verskillende rywydtes
Abstract
English: Several studies in especially the United States of America showed that soybeans
produced higher yields when planted in narrow rows as opposed to wide rows. The
higher yields were mostly attributed to better solar interception as a result of a higher leaf
area index. A denser leaf canopy increases water use efficiency and decreases weed
competition.
Therefore the influence of cultivars and row spacing on the growth and development of
soybeans was evaluated. The experiments were conducted at two divergent localities,
namely Bergville, Kwazulu-Natal and Bloemfontein, Free State during the 2000/01 and
2001/02 seasons with six cultivars (PAN660/564, Dumela, A5409, LS666, Tops and
SNK500) and two row spacings (0.45 and 0.90 m). An effort was made to use or imitate
commercial cultivation practices.
Several plant physiological components were measured, namely during the flowering
stage: plantheight, leaf mass, number of leafs, number of branches and leaf area index;
and during physiological ripe stage: number of pods, pod mass and seedmass. During the
flowering stage the nutrient concentrations in the above ground plant material was also
determined. The water use efficiency over the growing season was also quantified.
Neither the cultivars nor the row spacing had a significant influence on nutrient
concentrations in the above ground plant material. The water use efficiency, although not
statistically analyzed, was higher at the narrow than wide rows.
Most of the above ground plant components that were measured had higher values at the
0.45 than 0.90 m rows. The one plant component that stood out in this regard was the
number of branches that developed per unit surface area. When soybeans is planted at
the same density in the 0.45 and 0.90 m rows the distance between adjacent plants in the
narrow rows (0.074 m) is twice of that in the wide (0.037 m) rows. The consequence
thereof was that the soybeans developed significant more branches in the narrow than
wide rows.
The more branches in the narrow rows resulted in a more bushy plant which broaden
quicker. As a result of this together with the smaller distance between adjacent rows the
soil surface was covered faster and therefor a higher leaf area index at the narrow than the
wide rows. This higher leaf area index at the narrow than wide rows is in accordance
with results reported by other researchers. They suggested the higher leaf area index
resulted in earlier and higher solar interception. Although seed yields differed not always
significantly between the narrow and wide rows, the yields were consistent higher at the
narrow rows. Soybeans should be therefore rather planted in narrow (0.4 - 0.6 m) than wide (0.8 - 1.0m) rows if possible. An aspect that warrants investigation is the planting of soybeans at different densities in the narrow rows. Afrikaans: Verskeie studies in veral die Verenigde State van Amerika het getoon dat sojabone hoër
opbrengste by nouer as wyer rye produseer. Die hoër opbrengste word meestal aan beter
stralingsonderskepping weens 'n hoër blaaroppervlak-indeks toegeskryf. 'n Digter
blaredak verhoog waterverbruiksdoeltreffendheid en verlaag onkruidkompetisie.
Daarom is die invloed van cultivars en rywydtes op die groei en ontwikkeling van
sojabone onder plaaslike toestande geëvalueer. Die proewe is op twee uiteenlopende
lokaliteite, naamlik Bergville, Kwazulu-Natal, en Bloemfontein, Vrystaat, gedurende die
2000/01 en 2001/02 groeiseisoene met ses cultivars (PAN660/564, Dumela, A5409,
LS666, Tops en SNK500) en twee rywydtes (0.45 en 0.90 m) herhaal. Daar is sover
moontlik gepoog om by kommersiële verbouingspraktyke te hou of na te boots.
Verskeie plantfisiologiese komponente is gemeet, naamlik tydens die blomstadium:
planthoogte, blaarmassa, stingelmassa, aantal blare, aantal sytakke en blaaroppervlakindeks;
en tydens die fisiologies rypstadium: aantal peule, peulmassa en saadmassa.
Gedurende die blomstadium is die voedingstofkonsentrasies in die bogrondse
plantmateriaalook bepaal. Die waterverbruiksdoeltreffendheid oor die groeiseisoen is
ook gekwantifiseer.
Nie die cultivars of die rywydtes het enige noemenswaardige invloed op die
voedingstofkonsentrasies III die bogrondse plantmateriaal gehad me. Die
waterverbruiksdoeltreffendheid, alhoewel dit nie statisties ontleed kon word nie, was
deurgaans hoër by die nouer as die wyer rye.
Met bykans alle bogrondse plantkomponente wat gemeet is, is gevind dat dieselfde
cultivars hoër waardes by die 0.45 as 0.90 m rye gehad het. Die een plantkomponent wat
in die verband uitgesonder moet word, is die aantal sytakke wat per eenheidsoppervlak
gevorm het. Wanneer die sojabone teen dieselfde stand by die 0.45 teenoor die 0.90 m
rye geplant word is die afstand tussen aangrensende plante twee keer so ver by die nouer
(0.074 m) as wyer (0.037 m) rye. Die gevolg daarvan was dat die sojabone in die nouer
rye bykans deurgaans betekenisvol meer sytakke as in die wyer rye gevorm het.
Die meer sytakke by die nouer rye het ook 'n meer bosagtige plant tot gevolg gehad wat
vinniger in breedte toegeneem het. As gevolg hiervan, tesame met die kleiner afstand
tussen die aangrensende rye, is die grondoppervlakte gouer bedek en daarom is 'n hoër
blaaroppervlakte-indeks by die nouer as wyer rye gevind. Hierdie hoër blaaroppervlakteindeks
by nouer as wyer rye is soortgelyk aan resultate wat deur verskeie ander navorsers
gerapporteer is. Volgens hulle het die hoër blaaroppervakte-indeks tot vervroegde en
verhoogde stralingsonderskepping gelei. Alhoewel die saadopbrengs in hierdie studie nie
deurgaans betekenisvol tussen die nouer en wyer rye verskil het nie, was die opbrengs tog
deurgaans hoër by die nouer rye.
Daar kan dus met redelike vertroue aanbeveel word dat sojabone waar moontlik in nouer
(0.4 - 0.6 m) as wyer (0.8 - 1.0 m) rye aangeplant word. 'n Aspek wat egter ondersoek
moet word, is die aanplant van sojabone teen verskillende digthede in die nouer teenoor
wyer rye.