AGRICULTURAL RESEARCH INSTITUTE FOR SOUTH-EAST REGIONS

Saratov, 410020, Russia.

Performance of new spring durum lines.

N.S. Vassiltchouk, V.I. Kassatov, and V.M. Popova.

The main objective for spring durum wheat research at our Institute is to develop germplasm and cultivars for low-input production. In the Volga River region, low-input production is characterized by growing the crop with minimum fertilizer and without irrigation under typically dry conditions. Moreover, many farms now encounter economic difficulties and need varieties that give good yield and grain quality in these difficult situations.

We have developed several new durum wheat lines with more stable and higher yield and good semolina quality for pasta making in comparison with the check and our newly released varieties (Tables 1 and 2).

Table 1. Yield, 1,000-kernel weight, test weight, plant height, and days to heading of new promising lines

grown at Saratov (average 1993-95).

_____________________________________________________________________________________

Yield 1,000-kernel Test weight Plant height Days to

Cultivar (t/ha) weight(g) (g/l) (cm) heading

_____________________________________________________________________________________

Bezentchoukskaya 139* 1.01 36.4 780 89 44

Krasnokoutka 6* 1.21 38.1 777 85 43

Saratovskaya 57* 1.31 34.3 779 87 41

Saratovskaya 59* 1.31 39.3 762 79 41

Saratovskaya zolotistaya 1.29 39.1 750 86 42

Ludmila 1.42 39.1 788 93 41

D-2034 1.51 43.8 766 84 41

D-2013 1.62 38.6 770 85 41

D-2029 1.76 39.3 739 87 42

D-2030 1.78 38.5 740 93 43

LSD (5%) 0.19 2.2 14 4 1

_____________________________________________________________________________________

* Check

Table 2. Some semolina quality characters of promising new durum wheats grown at Saratov

(average 1993-95).

_____________________________________________________________________________

SDS- Falling Carotenoid

Wet gluten sedimetation number pigment

Cultivar content (%) test (ml) (sec.) (mg %)

_____________________________________________________________________________

Bezentchoukskaya 139* 33.2 33 410 4.8

Krasnokoutka 6* 33.3 44 409 5.2

Saratovskaya 57* 33.3 50 342 5.9

Saratovskaya 59* 33.1 49 372 5.2

Saratovskaya zolotistaya 32.4 46 444 8.2

Ludmila 31.5 54 389 5.7

D-2034 32.4 56 411 6.0

D-2013 33.7 57 377 7.2

D-2029 31.4 53 357 8.0

D-2030 34.6 58 402 9.1

LSD (5%) 1.8 4 44 0.6

_____________________________________________________________________________

* Check

The line D-2034, named `Valentina' in memory of a well-known Saratov spring wheat breeder Valentina N. Mamontova, will be in national tests in 1996. This cultivar originated from a selection in an F2 hybrid population of the cross `Saratovskaya 59/Leucurum 1897//D-1973/Saratovskaya zolotistaya'. Compared to Saratovskaya zolotistaya and Ludmila D-2034, Valentina has significantly higher 1,000-kernel weight, shorter plant height, and better lodging and loose smut resistance.

The leaf rust resistance of wheat somaclones.

S.V. Tuchin, D.A. Yusupov, and A. Yu. Kozlova.

A collection of wheat somaclones was screened for reaction to a Saratov population of P. recondita Rob. ex Desm. tritici. Adult plants (R2-R7 progenies) were tested under heavy field infection in 1993, and plantlets were studied under artificial inoculation by a wild-type population collected in 1993. The somaclones were developed from the spring bread wheat cultivars Saratovskaya 46 (S 46), Saratovskaya 55 (S 55), Saratovskaya 58 (S 58), and Ershovskaya 32 (E 32). Callus cultures were initiated from immature embryos on Linsmaer and Skoog's (LS) medium. Embryogenic calli were transfered to fresh LS media of various degrees of water chemical potential (WCP) depression. Two WCP depression levels (-9 J/mol, as a control, and -36 J/mol) were used.

After 30 days, plantlets were regenerated from both variants. In the field, sexual progenies of regenerants (R2-R7 from cultivars S 46, S 55, and S 58) and all four original varieties were susceptible to leaf rust. The somaclones developed from E 32 differed substantially in leaf rust reaction. Resistant, low reaction, and susceptible types occurred. The frequencies of resistant types were 32 % among control somaclones and 72 % among those adapted to the low WCP depression level (-36 J/mol).

Significant increases in plant yield were observed in the resistant somaclones compared to nonresistant ones and the original variety E 32. In order to check the heritability of resistance, several generations of somaclones were tested in the greenhouse. The eight somaclones showed seedling resistance, which was transferred successfully through a number of sexual cycles (Table 3).

Table 3. The reaction to leaf rust of somaclone seedlings in the greenhouse

(Original cv. Ershovskaya 32 = S; isogenic line cultivar Thatcher with gene

Lr23 = S).

_____________________________________________________________

Generation

___________________________________

Somaclone 1991 1992 1994

_____________________________________________________________

N 165 R RS RS

N 176 R R RS

N 181 R R R

N 184 R R RS

N 1591 - R R

N 1594 - R RS

N 1595 - R R

N 1596 - R R

_____________________________________________________________

R = resistant; S = susceptibile

The original cultivar E 32 has the gene Lr23 and has become susceptible to leaf rust in the last few years. We suggest that the increasing leaf rust resistance of the somaclones is connected with gene amplification as an in vitro stress reaction.

Use of molecular-ecological principles for plant-cell selection for drought resistance.

S.V. Tuchin.

Wheat-cell selection for drought resistance in relation to the molecular base of plant adaptation to environmental stresses was analyzed. The conditions for the successful production of drought-resistant plant somaclones were identified, a preliminary determination of tolerance, stress, and lethal regimes for cultured plant cells as a function of water chemical potential (WCP) depression in the culture medium; a crucial level of WCP-depression; and analysis of the nature of drought resistance in plant genotypes intended for improvement. The frequency of chromosome mutations in wheat under lethal levels of WCP-depression in callus culture medium is above 90 %. Adaptation of a tissue-cell population to dessication is the result of mutagenesis by controlling WCP-depression in the environment. In this case, WCP-depression is the signal that greatly influences the intracellular structures. The advantage of the crucial one-step selection was found by testing wheat somaclones adapted in vitro to extreme WCP-depression under drought conditions. These somaclones had better drought resistance than the parent cultivar, using yield as a criterion. The correct choice of the parental genotype intended for improvement in drought resistance must be made. Ignoring this principle leads to a decrease in agronomic traits of somaclones under drought conditions.

Effect of unfavorable environmental factors on productivity of cultivars of winter wheat.

S.V. Lyashceva.

Crop capacity is linked closely with environmental conditions as experienced in 1994 and 1995. In 1994, a thin, icy crust on the soil in the lowland caused a decrease in crop capacity. Productivity of all the studied cultivars of winter wheat growing where an icy crust occurred was 20 % (L 47/88 and L 50/86) compared to 90.9 % (winter hardy cultivar Saratovskaya 8) in those repetitions where the icy crust was not a factor. The cultivar Bezostaya 1 winterkilled. In strong drought stress (1995), productivity of these cultivars was reduced from 53.2 % (L 50/86) to 65.9 % (Lutescens 230) compared to more favorable years (productivity of the spring wheat cultivars was 3.5-4.0 times lower than in 1994). Because of the effective utilization of spring soil moisture, the number of productive lateral shoots was not reduced, whereas under poor winter conditions, a reduction of 1.4-1.8 times was observed. Unfavorable factors had a large influence on weight of ear. In winter-stressed conditions, the weight of vegetative organs also decreased. Length of ear also was reduced considerably. The drought had a greater influence on the number of grains per ear and 1,000-kernel mass than unfavorable winter conditions.