Growth and yield of six short varieties of spring wheat derived from Norin 10 and of two European varieties

Abstract

SUMMARYFive short varieties of spring wheat derived from Norin 10: Lerma Rojo 64A (R), Penjamo 62 (P), Sonora 64 (S), Mexico 120 (M), and an unnamed selection obtained from Mexico (X), had grain yields equal to, or only slightly less than those of the taller European spring varieties Kloka (K) and Jufy I (J). Yields ranged from 500 to 580 g/m2 of dry matter. The short variety NBJ115 (N) was severely infected with yellow rust and yielded only 290 g/m2. Total dry weight (excluding roots) of the short varieties was less than of J and K; hence grain accounted for 49 % of the total for the short varieties and 42 % for J and K. Most of the short varieties had fewer ears than the tall ones because sowing difficulties and poor germination produced fewer plants. The relative yields of X, P, R and S seemed to be correlated with their plant and ear densities.Leaf area duration after flowering (D), based either on total green area or on green area above the flag‐leaf node only, was less for the short varieties than for J and K. The apparent mean efficiency of this area in grain production (grain yield divided by D) was 50% greater for the short than for the tall varieties.The height of the short varieties ranged from 43 cm (M) to 79 cm (N). K was 92 cm and J 97 cm tall. Differences in height depended on the lengths of the top four internodes and not on number of internodes. Main shoots of all varieties produced seven or eight leaves. All varieties initiated spikelets 45–48 days after sowing. The short varieties flowered 103 days and matured 155 days after sowing; J and K flowered and matured about 1 week earlier.

Plant photosynthetic production as controlled by leaf growth, phenology, and behavior

“…Norman Borlaug visited Vogel and saw first hand what he had achieved; he then returned to his international lab in Mexico and crossed the dwarf wheat into Mexican and other lines, coming up with photoperiod-independent cultivars that led to part of the Green Revolution and his Nobel Prize. Thorne et al (1969) and Thorne and Blacklock (1971) were unable to repeat the Vogel's experiment in the UK; apparently because European tall cvs. did not lodge under high N fertilization.…”

Assimilation and Partitioning of Photosynthate and Nitrogen in Isogenic Tall, Semidwarf, and Doubledwarf Winter Wheats

“…Spikes were better sinks for photosynthates in the dwarf lines than in the tall line and, hence, the former were able to develop a greater number of grains per spike (McNEALet al 1972). That pattern of dry matter distribution also contributed to the increased harvest index of the dwarf lines (MCNEAL et al 1972, SPIERTZ and VAN DE HAAR 1978, THORNE et al 1969, WALCOTT and LAING 1976.…”

“…The most frequently noted advantage of semidwarf wheats {Triticum aestivum L.) is their harvest index (MCNEAL et al 1972, SPIERTZ and VAN DE HAAR 1978, THORNE et al 1969, WALCOTTand LAING 1976. Few studies, however, have explored the physiological basis for this advantageous harvest index.…”

“…Semidwarf cultivars may have a large grain-to-shoot ratio because a high proportion of the photosynthate produced after flowering is moved to the grain (THORNE et al 1969). Their leaf area, however, is no greater than that of tall cultivars (MAKUNGA et al 1978).…”

EFFECTS OF DECREASING THE LIGHT INTENSITY ON THE GROWTH OF AGROPYRON REPENS (L.) BEAUV. IN THE FIELD

“…At this time only a small percentage of the visible radiation incident on a spring wheat crop reaches the soil (e.g. Thorne et al, 1969). The lower leaves ofthe weed would be shaded more than the upper ones and the crop would filter out wavelengths useful in photosynthesis.…”