Effects of intercropping on temperate grasses canopy architecture and nutritive profile

This paper aimed to evaluate the impact of intercropping between oats and triticale species, over three defoliation cycles. The experiment occurred in two winters in a row, and was in split-plot randomized complete blocks design (20 plots) with five species combination, four blocks and three defoliations. The main plots were the species combination: black oat (Avena strigosa cv. IAPAR 61) – BO, white oat (Avena sativa cv. IPR Emerald) – WO, triticale (X Triticosecale Wittmack cv. Tpolo 981) – T; and the intercropping: black oat + triticale – BOT, and white oat + triticale - WOT. The sub-plots were the three defoliations cycles initially scheduled to be every 28 days. The intercropping between oats and triticale did not affect the accumulated dry matter yield (DM), but it also improved the pastures, as an increase on crude protein content (CP) (about 1.85% greater in WOT than WO; and 2.7% greater in BOT than BO). The number of leaves was also increased by the intercropping, from 4.2 (WO) and 3.7 (BO) to 7.6 (WOT) and 7.2 (BOT) leaves per main stem. Over the defoliation cycles, the maximum average of growth rate (2.72 t DM ha-1 ºCd-1), tiller per plant (10 tillers plant-1) and main tiller height (53.2 cm) were unanimously observed at third defoliation. The changes observed did not reduced the nutritional quality of the pastures, therefore both are highly indicated to these conditions.

Diversity of Productivity Traits in Hybrid Lines of Aegilops L. with Triticum aestivum L.

Variation in productivity traits and their correlations were studied in 16 hybrid lines of <em>Aegilops kotschyi</em> Boiss. and <em>A. variabilis</em> Eig. with <em>Triticum aestivum</em> L. and their parental components. In comparison to the wheat cultivars, most of the hybrid lines exhibited higher tillering, whereas the length of the main tiller and spike rachis were similar to the values for the wheat cultivars. The values of other traits, such as basal stem diameter, main spike density, fertility, and a 1,000-grain weight in hybrid lines were varied. In some lines, the value of these traits was higher or similar to that of wheat cultivars, whereas in others it was lower. Among the hybrids, [(<em>A. kotschyi</em> × ‘Rusałka’) × ‘Begra’] × ‘Turnia’ was distinguished in having the greatest basal stem diameter, longest spikes, highest fertility, and greatest 1,000-grain weight. The hybrid lines exhibited greater variation in the analyzed traits than did the wheat cultivars. In the hybrid lines, the main tiller length and basal stem diameter were positively correlated with fertility and 1,000-grain weight, whereas in wheat cultivars there were negative correlations for these traits. The results confirmed that wide hybrids can be used to eliminate the negative correlations between productivity traits in wheat. Analysis of clusters in terms of productivity traits provided information on the similarity and diversity of hybrid lines, which may prove useful in their further selection.

Response of wheat cultivars to early post-emergence herbicides containing MCPA (2-methyl-4-chlorophenoxyacetic acid)

In southern New South Wales in 1978 and 1979, the responses of 10 spring wheat cultivars to early post-emergence applications of MCPA, bromoxynil plus MCPA, and dicamba plus MCPA, were evaluated. The herbicides were applied at the rate recommended by their manufacturer (1x), and at 3 times this rate (3x). Cultivars differed in their responses to these treatments and herbicide tolerance was related to the stage of development of the apical meristem of the main tiller at the time of spraying. Olympic, Shortim and Egret were the most sensitive cultivars and their grain yield, averaged over rate and year, was reduced by 33, 19, and 15% respectively. Songlen, Jabiru and Durati were the most tolerant cultivars. Songlen was not affected by any herbicide, even when the 3x rates were used, while the grain yields of Jabiru and Durati were only reduced in 1 year, and then only by the 3x rate of dicamba plus MCPA. The remaining cultivars, Kite, Gamenya, Condor and Lance, were intermediate in their response to these herbicide treatments. Delaying the application of 1 of these herbicides, dicamba plus MCPA, until spikelet initiation, minimised yield reductions. Correlations between visual assessment of crop damage and grain yield reduction varied between cultivars and between herbicides.

The effect of photoperiod on the growth and development of Echinochloa spp. Millets

Two cultivars of Echinochloa utilis, Ohwi et Yabuno, and one E.frumentacea (Roxb.) Link cultivar were grown in a glasshouse under three photoperiod regimes: naturally varying photoperiods (1 2-1 3 h), and fixed photoperiods of 14 and 16 h. Both species behaved as quantitative short-day plants although, in E. utilis, extending the photoperiod from 14 to 16 h delayed head emergence disproportionately. The delay in head emergence did not affect the relative growth rate, and longer photoperiods led to higher shoot weights; main tiller leaf number increased only slightly. The commencement of apical meristem elevation was delayed under longer photoperiods, a feature believed to be beneficial to regrowth. A time-of-sowing study in the field illustrated the effect of this short-day response upon crop development. Sixteen introduced E. utilis cultivars and 10 E. frumentacea cultivars also behaved as quantitative short-day plants. Within each species there were differences between cultivars in sensitivity to photoperiod. Some cultivars of E. utilis were very late and had abnormal head emergence at 16 h. Latitudinal effects on the performance of these cultivars are discussed.

COMPLETION OF THE JUVENILE STAGE IN ORCHARDGRASS

Three orchardgrass strains of different origins were used to determine the stage at which seedlings become capable of responding to induction treatment. The seedlings were grown under long photoperiods and warm temperatures after emergence until the sixth to ninth leaf appeared on the main tiller (shoot), and were then exposed to the induction conditions (10 hr photoperiod at 10 C) for 6 weeks. The juvenile stage in all three strains was completed at the eighth to ninth leaf stage. From the practical point of view, the eighth leaf stage can be used as an indicator of the completion, since about 90% of the seedlings induced at this stage subsequently developed heads, compared with 100% at the ninth leaf stage and 30–60% at the seventh leaf stage. Different photoperiods (14, 17, 24 hr) and different temperatures (15.5, 21 C), prior to the induction treatment, influenced the rate of leaf appearance, but did not affect subsequent heading. The maximum rate of leaf appearance occurred under long photoperiods (17 and 24 hr) and a warm temperature (21 C). Under these conditions, seedlings reached the eight-leaf stage in 3–4 weeks after emergence. The number of tillers was not as good a criterion of the completion of the juvenile stage as was the number of leaves on the main tiller.

Vascular System of the Stem of the Wheat Plant. I. Mature State

The courses of the various vascular bundles in the nodes of the main tiller of Triticum aestivum L. have been reconstructed from anatomical observations of con- secutive serial transverse sections. Of the bundles entering a node (n) from its attached leaf, the first-formed and largest, the median, passes directly through the node to the second node below (n-2), where it bifurcates and fuses with other strands. These continue to node n- 3 before fusing completely with the nodal plexus. The next six bundles to form (laterals) establish some links with bundles from higher leaves in the node of entry, much more extensive connections in node n- 1, and fuse completely with the nodal plexus in node n-2. The next four lateral bundles to differentiate are more extensively linked in node n and fuse completely with the nodal plexus in node n - I . The remaining 16-20 bundles from the leaf (intermediates) follow much the same course but develop more extensive connections with other bundles. The extensive plexus which develops in each node ensures vascular connections between most bundles. The significance of these in transport is briefly discussed.

Vascular System of the Stem of the Wheat Plant .II. Development

The sequence of vascular differentiation in the shoot of the main tiller of Triticum aestivum L. was reconstructed from seriai transverse sections of shoot apices made at various stages of development. The pattern of initiation and development of the pro- cambial strands was confirmed. The provascular bundles of the pith plexus arose independently and developed acropetally from the base of the future node. Early dif- ferentiation of proto-phloem and -xylem in the main procambial strands proceeded bidirectionally up the leaf primordia and down the stem from a site of initiation isolated from other differentiated vascular elements. Further development was basipetal from the tip of the primordia, and the rate of differentiation of the sieve elements was sufficient to maintain phloem continuity across the intercalary meristems of the laminae, sheaths, and internodes. Within the developing nodes sieve tube differentiation in the cross-linking strands lagged behind that of the leaf traces they interconnected, and this may influence the movement of photoassimilate from a recently expanded leaf to the apex.

Ryegrass populations from intensively managed leys:I. Seedling and spaced plant characters

SUMMARYSeed of Lolium perenne L. was grown from material collected from three S.23 leys and one S.24 ley that had been subjected to high rates of stocking and nitrogen application. Comparisons were made between plants grown from seed derived from the leys and from breeders' seed of S.23 and S.24.Seedling characters indicated that the populations derived from leys differed from each other and from the plants grown from breeders' seed. In S.23 populations the main change occurring in intensively grazed leys was towards higher tillering prostrate seedlings. This did not occur in the S.24, but here the survivor population had a slightly shorter fifth leaf and a lower number of leaves on the main tiller of the seedlings.As spaced plants, the population derived from the S.23 ley, with the highest percentage ryegrass and the reputation for the highest yields on the farm, gave a higher yield, recorded in three cuts in the first year and in four cuts in the second year, than any other populations. Small differences between S.23 populations in aftermath heading, reaction to rust, and mean date of panicle emergence were recorded. Variance of spaced plant yield decreased in ryegrass derived from older S.23 leys. The S.24 ‘survivor’ population was much later in mean date of panicle emergence than S.24 grown from breeders' seed.

Response of Mitchell grasses (Astrebla F. Muell.) to photoperiod and temperature

Controlled environment experiments were carried out to determine the effect of temperature and photoperiod on Astrebla pectinata, A. lappacea, A. elymoides, and A. squarrosa. Photoperiod had little effect on growth and development of tillers and on floral initiation, but did affect numbers of emergent inflorescences. Usually, inflorescence production increased with decreasing photoperiod. Temperature had significant effects on all parameters measured (number of main tillers and emergent inflorescences, elongation of main tillers, and number of leaves and axillary tillers per main tiller). Growth per tiller and leaf production increased with temperature (up to 30/25�C) but for tiller numbers the optimum was about 28/23�, Geographically separated strains of A. pectinata generally exhibited similar responses to photoperiod and temperature while different species from the same location differed in their response.